clinical research recruitment techniques

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Clinical trial recruitment 101: how to recruit participants for a study, what is the best way to recruit participants for a study.

There is no simple answer to the question of how to recruit participants for a study in clinical research. The ideal recruitment strategy will depend on the specifics of the trial type and protocol, the capabilities of the sponsor and/or entity conducting the trial, the availability of eligible participants, and certain demographic and behavioral factors of those participants.

This article provides various resources for trial sponsors and clinical researchers to dive deeper into aspects of patient recruitment, and then answer the above question in a way that makes sense for the trial in question and their organization's unique needs.

Ethical considerations in research study recruitment

Before we proceed with answering “how to recruit participants for a study,” let’s do a quick recap of ethical considerations in research recruitment. There are a few important things to keep in mind related to regulatory compliance, ethics, and IRB submissions/approval. Keeping these concepts present through the design of the recruitment plan and during enrollment will make recruitment processes smoother by avoiding unexpected delays due to disapproval of study materials or re-approvals for unforeseen changes to said materials.

So, what are ethical considerations in relation to patient recruitment for clinical research studies? Essentially, the following rules and regulations are put in place to protect patients - in terms of their health and safety, their basic human rights, their data and personal privacy - and to ensure they are treated in an ethical manner (i.e., fairly and humanely) throughout the clinical trial, which begins with their first exposure to the study, be it through their physician or through promotional material. These considerations are provided in a bullet-point list to serve as a global overview that is easy to navigate – more information can be found by following the references provided at the end of the list.

1. All study materials must be approved by an IRB - Anything that will be seen by participants requires IRB approval prior to them seeing it. If modifications are made, a modification application must be submitted. Keep potential delays here in mind, and consider designing alternative versions to allow quick swap-out of pre-approved study materials.

2. Required content for recruitment materials - Recruitment materials generally must contain the following information:

• Clear indication that it is a research study (and not a therapy, program, etc.)
• Clear description of the purpose of the research study
• Basic eligibility criteria (those which a prospect can assess him/herself)
• Requirements of the participant (timeline, study visits, procedures, etc.)
• Location (of study sites or indication that it is a remote trial)
• Regulatory status of the investigational product/drug/device, if applicable
• Contact information

3. Prohibited content/terminology in recruitment materials - The following are forbidden from being included in recruitment advertisements:

• Promises of free healthcare or treatment
• Compensation that is highlighted or otherwise made to stand out from the rest of the text/content
• Claims that the investigational product is safe, effective, or equivalent to another treatment/product
• Claims that the trial will lead to health benefits or positive outcomes for the participant
• Exaggerated allusions to benefits, whether personal or societal
• Promises of discounts on the investigational product after its approval

4. Voluntary participation - Researchers must take explicit care to avoid coercion and inducements in research. Research participants may not be urged, forced, or coerced to take part in research studies.

5. Respect targeted ad bans and online privacy - Many social media platforms have banned the use of targeted advertising, wherein users’ sensitive personal information is used to target them. Ads not respecting these rules will not be approved. Recruitment outreach and communications must respect the privacy of every individual, and those interactions must not reveal their condition or identity to third parties or the public.

6. Data confidentiality and security - Data collected about potential participants should be treated as confidential, and should be stored appropriately (securely) to avoid data breaches and leaks of personal data that can compromise personal privacy.

7. Clear, direct, and unbiased language - Language should be understandable by the average person (layman terminology), and study objectives and protocol details should be laid out directly and clearly, avoiding misleading statements, coercive wording, and unfounded or exaggerated promises or claims.

8. Circumvent the therapeutic misconception - Study materials should deliberately avoid the “therapeutic misconception,” wherein participants believe that taking part in a study is guaranteed to benefit their health.

9. For further information on these points, please refer to:

• Recruitment of Research Participants Ethical Considerations
• Ethics in Clinical Research | Clinical Center Home Page
• Ethical Considerations in Clinical Research: A Comprehensive Review
• Clinical Trial Recruitment Practices: The Evolution of Ethical Considerations - WCG IRB

Powerful recruitment strategies: From planning to consenting

Our aim with this article is to provide sponsors and researchers with an overview of multiple concepts and considerations that come into play when designing and executing an effective patient recruitment strategy. We all know that recruitment can be a source of costly setbacks. Optimizing recruitment begins well before the recruitment process begins - due consideration of common challenges is necessary in order to understand the target population, promote diversity, and design recruitment strategies that are effective. This includes designing trials that are optimized for recruitment success. After discussing these challenges and considerations for designing recruitment strategies, we will provide further information on specific recruitment methods, including pointing to some powerful recruitment tools to supplement recruitment activities and the options available for outsourcing recruitment to specialists. Finally, we will link to explanatory content that goes into greater depth about various marketing and outreach strategies on different platforms to optimize exposure and speed up enrollment by reaching the right participants.

Importantly, recruitment success begins with designing trials and protocols that are already set up with recruitment success in mind! See our articles on patient centricity and decentralized clinical trials as a starting point. From here on, we will focus on optimizing recruitment, assuming that the trial has been designed in consideration of minimizing patient burden and enhancing participant experience. If that’s not the case, the following tips will still be entirely useful - but keep these concepts in mind for future trial designs, as patient centricity is slowly but surely becoming the norm rather than the exception in the clinical research industry.

Have a look through the following sections, which we have conveniently split up into three broad stages/concepts to help you pick and choose the guidance that is pertinent to the aspect of recruitment you’re looking to improve.

A. Background information to guide the design of a recruitment strategy

Recruitment challenges, eligibility criteria and screening, diversity and underserved populations

Recruiting into research studies is a complex undertaking. It requires a thorough understanding of your target population, including a clear definition of eligibility criteria for the trial, and it’s really useful to understand some of the (unfortunately, very) common issues that clinical researchers face in recruiting and enrolling a sufficient number of eligible participants on time.

Now, back to the design of the recruitment plan. To begin, check out the following resources to gain a deeper understanding of the clinical research recruitment landscape and common challenges encountered. This information is powerful for enabling you to turn these challenges into insights in order to come up with ways to address them and prevent them from becoming problematic.

• Three Clinical Trial Recruitment Challenges and Strategies to Overcome Them | Power
• Challenges in recruitment and retention of clinical trial subjects - PMC
• Enrollment in Clinical Trials: Statistics and Patient Recruitment Strategies | Power

Next, let’s consider the eligibility criteria. Nearly every trial has them, as these constraints act to encourage some degree of homogeneity in the sample, which in turn improves statistical power. In other words, constraining the sample allows researchers to control for certain covariates and prognostic factors, at least to some degree. These can include basic demographic factors such as biological sex and age, or extend to extremely specific criteria such as narrow ranges on a certain clinical parameter (hypothetical example: average systolic blood pressure of between 100 and 110 mmHg over the last 6 months). The trade-off is that strict eligibility criteria limit the pool of potential participants, and results obtained from very narrowly defined subsamples of the general population are less likely to be generalizable to the broader population. For extremely rare diseases, it makes more sense to use broader eligibility criteria so as not to unrealistically limit the sampling pool, and further since the rare condition is already a highly specific criterion. Eligibility criteria are also put in place as a safeguard against exposing high-risk patients to drugs or interventions that may be particularly risky for them.

Clinical researchers should aim to strike a balance between accessibility (to a sufficient participant pool for researchers, and fair accessibility to the study for diverse populations) and statistical power, and keep generalizability of results and the representativeness of the sample in mind. Check out the articles below to dive deeper into defining appropriate eligibility criteria and the factors involved in the decision:

• Clinical Trial Basics: Eligibility Criteria in Clinical Trials | Power
• Setting Eligibility Criteria - Ora Clinical
• Clinical Trial Eligibility Criteria | ASCO

The final consideration we want to touch upon in the context of planning and designing effective recruiting strategies is diversity in trial participation. This has become an important topic over the past years, as it has become evident that many minority groups and communities are (sometimes significantly) under-represented in clinical research studies. Diversity and inclusivity in clinical trials are important for multiple reasons. First, there are genetic differences amongst the broader population which can have significant impacts on how individuals respond to treatments - ensuring inclusion of diverse populations improves the representativeness of the study sample, and increases the likelihood that results can be generalized. Further, this helps monitor, to some extent, for potentially dangerous responses to a given treatment in certain groups, which may not have been identified in a sample that did not represent those groups. Second, the under-representation of certain groups can be a reflection of the reality of unequal access to healthcare and potentially beneficial novel treatments in certain communities. Not only is this a discrepancy that should be rectified for the sake of fairness and ethics, but increasing awareness and rapport in these communities can work toward dispelling negative perceptions and misconceptions that may act as confounding factors toward the lack of involvement. Check out the following article and the FDA guidance for more info:

• Clinical Trial Basics: Underserved Populations in Clinical Research | Power
• Diversity Plans to Improve Enrollment of Participants from Underrepresented Racial and Ethnic Populations in Clinical Trials Guidance for Industry | FDA

B. Recruitment methods and tools

Recruiting methods, powerful recruitment tools, and outsourcing

Now, let’s get to directly answering the question originally posed: How to recruit participants for a study.

The first topic here is pre-screening. Pre-screening is an invaluable step for narrowing down interested participants to high-interest/high-eligibility candidates, preventing costly screen failures down the line. In many cases, pre-screening can be set up and then function passively, greatly reducing the workload on sites and investigators. At Power, our speciality is matching patients with relevant clinical trials, which is powered by our patient-friendly platform. The powerful pre-screening feature serves a double purpose in that prospects’ answers to sponsor-defined pre-screening questions are used to create a database of high-interest participants, which makes it extremely easy for sponsors to reach out to further them through the recruitment funnel. If you’re recruiting for a study, reach out to us and verify your trial on our platform with a streamlined pre-screening feature. Check out the following link for more information on pre-screening and screening:

• Clinical Trial Basics: Pre-Screening and Screening | Power

In terms of executing the recruitment and outreach strategies, there are various ways to go about it. The following links will bring you to great resources outlining specific recruitment methods, focused on patient-centric recruiting strategies and tools that can help you succeed in recruitment. Have a read through; we’re sure you’ll find something that helps you design the best recruiting strategies possible for your trials:

• Recruiting for clinical trials: Patient-centric clinical trial recruitment strategies that work | Power (Scroll down to “Recruiting for clinical trials: Six patient-centric recruiting strategies”)
• 9 Clinical Trial Recruitment Tools to Try in 2023 | Power

If all of this seems like simply too much to take on - this is often the case for smaller organizations - there may be real value in considering outsourcing recruitment efforts to specialists in clinical research recruitment. These could be a dedicated clinical research recruiter, or CROs or other providers who offer recruitment services and bring their own site and patient databases to the table, amongst other operational services and technological solutions:

• Top 10 Patient Recruiting Companies for Clinical Trials in 2023 | Power

C. Clinical trial marketing and outreach campaigns

Guidance for digital marketing campaigns on social media, Google, and Facebook

In today’s clinical research industry, which is more connected than ever before yet still suffers from poor recruitment statistics, trial recruitment specialists and sponsors have turned to marketing tactics to expand exposure to their trials. Capturing the attention of people, who are bombarded by advertisements on a daily basis - an estimated 4,000 to 10,000 per day, in fact - is increasingly difficult (and that statistic is from a few years ago already!). Thus, there is a lot of value in leveraging marketing techniques to increase exposure of your trial. As a starting point, have a look through our introductory article on the topic of clinical trial marketing:

• How-to Guide: Clinical Trial Marketing | Power

When it comes down to specifics, things can begin to look quite complex. Different social media platforms with differing user demographics, different ad types, and distinct rules and regulations, combined with the fast-paced nature of social media and digital marketing, highlights the potential value in partnering with a digital marketing expert. However, with some dedication and time, it’s not all that hard to navigate these platforms and design and launch highly effective recruitment campaigns on social media.

We recommend first reading through the concise and helpful “Use of Social Media” section of this guidance published by the Iowa State University Institutional Review Board , which serves as a checklist to ensure that you have the appropriate perspective and awareness of pertinent issues when going into this area. Relatedly, our overview piece on social media recruitment goes into depth on important considerations for patient privacy, targeting methods in light of targeted ad bans, common challenges and potential solutions in social media recruitment, designing and monitoring a recruitment campaign, and gives an introduction to the major platforms and their specific ad campaign types:

• Designing Effective Social Media Clinical Trial Recruitment Campaigns in 2023 | Power

If you’re interested, take a look at more detailed guidelines for two of the major online marketing channels that have proven to be extremely effective for many clinical trials: Facebook and Google.

• Facebook Clinical Trial Recruitment: Strategies for Effective Facebook Advertising in Medical Research
• Google Clinical Trial Advertising: Getting the Most Out of Google Ads for Recruitment | Power

We hope that this global overview of important considerations, challenges, and methods of recruitment has been useful, and that you can walk away with some helpful information for how your organization or trial team might go about deciding how to recruit participants for a study. There are a lot of options for patient recruitment, but perhaps the most important aspect of recruiting into research studies that we would like to highlight is the benefit of proper prior research and planning. Past trials offer extensive insight into what has and has not worked, either in your organization or for trials of a similar nature, and taking time to define and then understand your target population - their needs, their struggles, and where they are most active - will go a long way in optimizing your recruitment efforts. Bring patient experience and recruitment success to the table early on, in trial design and protocol development, to set the study up for successful and quick recruitment from the get-go. Whatever strategies and tips you decide to adopt, keep regulatory compliance and IRB approval in mind, and remember that recruitment is a skill. Especially in these times of extreme connectivity and exposure to advertisements, learning to reach your target participants with messages that resonate with them is an art, which you can only improve upon with each trial and each iterative effort.

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Participant and patient engagement, recruitment, and retention

Need assistance with participant engagement, recruitment, or retention?

Get help with participant engagement, recruitment, or retention.

Contact the Recruitment Innovation Center (RIC):

• Submit a help request

Successful participant engagement, recruitment, and retention in research studies  can be one of the most challenging aspects of conducting research. Effective and efficient engagement, recruitment, and retention strategies are critical to successfully achieving enrollment targets while also prioritizing participant safety, well-being and trust.

This page provides resources, best practices and tools for developing and implementing robust engagement, recruitment, and retention strategies. However, it’s important to note that there is no one-size-fits-all approach to good planning. In fact, effective engagement, recruitment and retention planning should:

• Be proactive
• Start upstream at study design
• Anticipate and account for downstream barriers
• Be data-driven and evidence-based
• Be thoughtful and realistic
• Include input from all relevant stakeholders
• Be participant-centered
• Be resourced appropriately
• Be adjusted as needed

Request a free consultation with the Recruitment Innovation Center or consider the Consultations and Help resources available in the “Related Resources” section.

Population or cohort discovery

Participant or patient engagement and recruitment strategies.

Once the cohort or population has been identified, recruitment plans should consider which strategies and messaging are most appropriate to engage the intended audience, while also adhering to Federal Regulations and institutional policies and guidance.

Before identified potential participants can be recruited engagement must happen. Engagement, in this sense, is about delivering content to the right person, at the right time, with the right frequency, through the most effective channel.

True stakeholder engagement should happen as early in the study design process as possible. However, that’s not always an option when Duke is a participating site in “someone else’s research study” – when this is the case, we think of engagement as the strategies used to share information about a study with potential participants. This may include one or more of the following channels:

• Duke Health Research Volunteer Registry
• ResearchMatch
• Social media (e.g., Facebook ads)
• Print media (e.g., flyers, brochures, etc.)
• Online/digital content (e.g., a study website or search engine ads)
• Radio or TV spots
• Letters or emails
• Phone scripts for personal phone calls
• MyChart messages

Advertising, regardless of the chosen channel(s), must follow federal regulations, Duke policies, and Duke branding requirements. Links below provide information about allowable typography, colors, use of logos, and additional tools.

• DUHS Brand Center
• School of Medicine Brand Guidelines
• Duke University Brand Guide
• DUHS Policy and Guidelines for Advertising Research
• DOCR Social Media Recruitment SOP

Discover Duke Research 

The Recruitment Innovation Center manages the Discover Duke Research Facebook and Instagram pages and offers free social media marketing consults to all Duke research teams. During a social media marketing consult, the RIC team and investigator will work together to begin drafting a social media marketing plan to submit to the IRB for approval. Ads can be launched by the RIC from the Discover Duke Research accounts (Facebook/Instagram, Reddit, and Google) or the investigator may launch them from another approved social media channel per the Duke Social Media Recruitment SOP . RIC services (e.g., assisting in the development of a social media marketing plan, acquiring high quality images for advertising, managing the campaign, etc.,) are free of charge but there is a fee for the ads themselves.

• Request a  social media marketing consult .
• Review other available Policies, Procedures and Guidance in the "Related Resources" section of this page.

Duke Health Clinical Trials Directory 

The Recruitment Innovation Center manages content on the Duke Health Clinical Trials Directory . Reviewing the SIP Console Training in LMS (course #00129901) is recommended before reaching out to the RIC for assistance ( [email protected] ) in having a study posted on the Directory.

Engagement, recruitment and retention planning should take into consideration best practices for literacy, numeracy, and health literacy as well as principles of good readability. Principles of readability and tailoring to the health literacy needs of a population include adherence to the following principles:

• Responsibility : Clear research communication is the responsibility of all stakeholders in the research enterprise
• Life Cycle Adherence : All research communication should be clear and easy to comprehend throughout the research life cycle
• Partnership : Research communication should be developed in partnership with the intended audience(s)
• Cultural Sensitivity and Respect : are integral to clear communication about research
• Tailoring : Research materials for participants should integrate literacy and health literacy practices, including plain language, numeracy, visualization and design techniques, and cultural considerations
• Evaluation : Participant research materials should be evaluated to ensure the intended audience can understand the information
• Confirmation : In-person communication should encourage dialogue and confirm understanding
• Institutional Support : All stakeholders in the institutional research enterprise should support the development and implementation of organization policies that integrate literacy, numeracy and principles of good readability

Engagement, Recruitment, and Retention Certificate Program

The Engagement, Recruitment, and Retention Certificate Program is a certificate and skills-building program designed for Clinical Research study teams. The intention of the program is to help staff develop and expand competency in participant engagement, recruitment, and retention.

Participant Retention Strategies

Good retention starts with a strong, feasible, well-considered engagement and recruitment plan and a participant-centered research study. Many a study has been derailed by inadequate attention to recruitment and retention barriers and lack of effective strategies to overcome them.

Approaching recruitment and retention by ensuring a protocol is participant-centered will enhance the chances of a successfully completed study that finishes enrollment on time with a strong retention rate. Being participant-centered requires an investigator to consider every element of the project from the perspective of a participant and a variety of other characteristics (e.g., relevance of the study question to them, motivation - altruism, compensation, access to novel therapy, etc. - disease state, therapeutic options and opportunity costs, etc.). Adopting both a participant-focus and a quality-by-design framework can help examine study objectives and identify the factors that are critical to achieving them, while minimizing the burden of participation for participants. In terms of recruitment and retention, this should (at minimum) include attention to the following:

• Eligibility criteria – each criterion should be reviewed for its importance to achieving the study aims, its effect on the availability of the population and its acceptability to providers, participants and (if applicable) patient advocacy organizations.
• Accrual feasibility – does the study population as described actually exist? Is there one (or more) particular criteria that will weed out a large number of potential participants? Are there adjustments to the eligibility criteria that should be made?
• Adequate compensation – not all studies have the option of compensating participants. However, it’s important to consider the time, effort and hassle participants are enduring to take part in a study. Compensation in the form of money, expense reimbursement (e.g., travel, parking, meals), meaningful/useful tchotchkes or give-aways, etc., are all appropriate methods of compensating participants.
• Study procedures and event schedules – are the study procedures, including their invasiveness and risks, length and frequency of visits and location of participation particularly burdensome for the target population?
• Feasibility in the clinic – examine the study from the perspective of providers and clinic staff and their daily clinic operations. Will the study impact their clinic workflow? Engage them early in study design to mitigate against this risk; otherwise, ensure flexibility to minimize disruption.
• Reducing the burden of participation – research participants are often busy people, deeply embedded in dynamic personal lives. A research study is not part of their job. Providing flexible appointment times, short visits, and convenient locations for in-person study visits can ensure that it’s easy for participants to remain in a study. Consolidate visits when possible and provide “remote” options when feasible.
• Clear, frequent communication – Well-timed communication, including study visit reminders, via participant-preferred methods (SMS, email, phone call), an updated website, newsletters about study progress and milestones achieved, etc. are all good ways to keep participants engaged and interested in a study. Lay summaries of findings can be useful, especially if an abstract or a poster about the project is published.
• An attitude of humble gratitude – People are not required to participate in research. Their participation is a gift to be appreciated. Frequent communication of gratitude and recognition of the time and effort participants are sharing is often cited by participants as important to their continued participation. A commitment to providing a lay-summary of the study results at the end of the study is a great way to demonstrate appreciation and turn research participants into research evangelists.

Through Innovation, Connections, Collaborations and Education, the Recruitment Innovation Center is available to help with recruitment needs. For assistance and support across the enterprise, reach out to the RIC at [email protected] or request a consult today.

Insights & News

5 key strategies for clinical trial patient recruitment.

Are you interested in learning more about clinical trial patient recruitment strategies? If so, then you’ve come to the right place! A successful trial depends on the recruitment and retention of patients, which can be a challenging process, but this is an essential element for the completion of your trial.

One of the most important steps in developing and testing novel medical treatments is conducting a clinical study. Unfortunately, we can see numerous studies being closed or delayed due to poor recruitment.

Let’s review the best practices for recruiting patients for clinical trials, such as ways for identifying and contacting prospective participants, as well as strategies to keep them engaged throughout the whole duration of the clinical trial. We’ll also review how working with a therapeutically aligned contract research organization (CRO) for your study can alleviate some of the challenges you may encounter in your study’s patient recruitment journey.

Table of Contents:

• 5 key strategies to consider for successful patient recruitment

How can a CRO like Proxima help with patient recruitment?

You've got a plan, a potential therapy, medicine, or device, and you're ready to start clinical trials. But do you really know what it takes to successfully bring your product to market? A patient-centric approach! Let's take a look at some of the best techniques for patient recruitment in clinical trials.

The 5 key strategies to consider for successful patient recruitment

1. Identify your patient population: Before you start recruiting patients, it's important to have a clear understanding of who you're targeting. This might involve identifying particular age groups, genders, or other demographic traits, along with the medical condition and treatment being studied.

2. Use a wide variety of recruitment methods: To increase your chances of success, it's advisable to use multiple methods for reaching potential clinical trial participants. This might include placing ads in local newspapers or on websites, working with patient advocacy groups or healthcare providers, or using social media to help spread the word.

3. Make it easy for potential participants to get information: When people are considering participating in a clinical trial, they will have questions. Whether it's through a dedicated website, a toll-free hotline, or in-person information sessions, it's important to make it as effortless as possible for them to get the information they need.

4. Offer incentives: Even though most people who participate in clinical trials do so because they want to promote medical research, it can be useful to provide other incentives to participants. This might involve receiving payment for their time and travel or receiving free medical attention or treatment.

5. Keep participants engaged: Once someone has decided to take part in a clinical trial, you now need to keep them motivated to stay in the trial. This could involve giving regular updates on the trial's progress, providing support and resources to help participants handle any challenges or adverse effects, and being sure to answer any questions or concerns they may have along the way.

It's also worth mentioning that there are a few things to avoid when it comes to patient recruitment in clinical trials. For example, it's important to ensure that you're not coercing or pressuring people into participating. You’ll also need to fully disclose all relevant information about the trial and any potential risks associated with their participation. Also be sure to consider cultural and language differences, making sure that trial materials and communications are accessible and understandable to all participants. 

Being proactive and working with a clinical trial partner early in the process can help to create a patient recruitment plan that tackles the recruitment barriers mentioned above.

Choosing a knowledgeable and experienced CRO capable of leveraging the right relationships has a direct impact on patient recruitment. Proxima has experience in 27+ therapeutic areas for medical devices and drug development, so our team can quickly identify the needs and goals of your trial to then help select the most patient-centric clinical site for your study. Having a well-run, professional site means that patients will have more autonomy, conveniently accessible tools, and resources, and will be well-informed about their responsibilities and expectations. 

You need a capable CRO with strong site relationships that will provide you with open communication and trust, resulting in improved patient recruitment and retention, as well as trial outcomes.

We also help you put your protocol into action by helping you identify the study population, criteria, and recruitment objectives, as well as assisting you through the protocol submission process to the IRB. We can remove any barriers that stand in the way of a clinical trial's effective recruitment and success by combining our expertise in data administration, site partnerships, and patients' needs.

Overall, patient recruitment for your clinical trial will require careful thought and planning, but with the appropriate strategies in place, you can effectively enroll the patients you need on time. Simply following the recommended practices stated above will increase your chances of improving the field of medicine with speed and agility.

Institutional Review Board

Health Sciences and Minimal Risk Research IRBs

Recruitment Guidelines

May 25, 2022

This section of the Investigator Manual outlines recruitment guidelines, including initial contact, email recruitment, clinical recruitment, and social media recruitment.

General Recruitment Guidelines

Initial contact guidelines, email recruitment guidelines, clinical recruitment guidelines, mychart recruitment guidelines, social media recruitment guidelines, eligibility screening.

The IRB reviews study recruitment methods (including advertisements and payments) to evaluate whether they will affect the equitable selection of participants, and to ensure that the proposed methods adequately protect the rights and welfare of participants.

The protocol document or application must include a description of the following: (1) the source of subjects for all study groups (intervention/case and control); (2) when, where, how, and by whom these potential subjects will be recruited; (3) the methods employed to identify potential subjects; and (4) the materials used to recruit subjects, including the use of email and text messaging. If this is a multi-center study in which subjects are recruited by methods not under the control of the local site, e.g., call center or national advertisements, describe those methods.

The IRB must review and approve the content of all recruitment and advertisement materials, including oral communications, before implementation. For guidance on what to include in an advertisement, refer to the “Preparing Recruitment Materials” section as well as HRP 315-WORKSHEET-Advertisements .

These guidelines apply to all research studies that will identify and recruit participants. For guidelines specific to recruiting in a clinical health care setting, refer to the “Clinical Recruitment Guidelines” section.

• Advertising and recruiting procedures must protect potential participants’ confidentiality. In particular, names and contact information for potential participants must be collected and maintained in a confidential manner.
• When obtaining the names of potential participants from third parties, you must consider whether any breach of confidentiality or privacy laws has occurred. For example, doctors must contact their patients for written permission before releasing their names to a third party.
• You are responsible for ensuring that approved procedures are followed by any third parties (e.g., therapists, teachers, or social-service providers) who may be aiding in the recruitment and/or advertising process. Payment to professionals in exchange for referral of potential participants (“finder’s fees”) and payment tied to the rate or timing of enrollment (“bonus payments”) is prohibited.
• If a researcher plans to use snowball sampling to recruit participants, the participant population should be considered. For example, for certain populations, just providing a name or contact information to the researcher could present a risk to the potential participant. In these situations, the researcher could instead provide a business card to a participant with the directive “I am looking for others who may be willing to talk with me. If you know of anyone, please ask them to contact me, using this information.”
• You may not share names of previous research participants with other researchers without permission from the participants.
• The number of times a study team can attempt to contact participants is study dependent and the appropriateness of that number will be assessed by the IRB.
• Email is generally not a secure way to communicate sensitive or health related information as there are many ways for unauthorized users to access email. You should avoid sending sensitive, detailed personal information by email. Email should also not be used to convey information of an urgent nature. If you need to talk to someone immediately or would prefer not to receive study communication by email, please contact [Name, Title, Phone Number].

Link to this section

• Mailed recruitment letters: Letters, whether or not they precede a phone call, should be clear regarding why the potential participants are being contacted and how the individual(s) sending the letter have identified the potential participants. Letters sent to patients should be signed by someone who, by virtue of their position, patients would reasonably expect has access to their health information (see Clinical Recruitment Guidelines ).
• Recruitment of subjects from a previous study for a follow-up or other related study: Letters should refer to the study in which the individual has already participated and state how the new study is related to it.
• Recruitment of children through their school: Letters should be addressed to parents/guardians; it can be provided in a packet that children take home with them.

If you plan to recruit or screen potential participants by phone, the IRB requires you to use a script to ensure consistency and completeness in the information that potential participants are given about the study or screening questions. You will need to upload these scripts as part of the IRB application. The IRB generally requires that phone calls to patients are preceded by a letter (see Clinical Recruitment Guidelines ).

For additional guidance on drafting recruitment letters, phone scripts, and eligibility screening scripts, please see Appendix B: Recruitment Elements and Scripts .

• Only secure, university-issued or approved email accounts should be used, such as @wisc.edu, @medicine.wisc.edu or @uwhealth.org accounts. Personal email accounts, such as @gmail.com, may not be used. Use encrypted email if possible.
• Email addresses must not include references to health information or other potentially sensitive, private information (e.g., [email protected]).
• Protocols or applications must describe how email will be used, including the source of email lists, targeted populations, frequency of emails, and methods for potential participants to remove themselves from the email list.
• You will need to provide email templates used for recruitment purposes. The subject line and content of these emails should not contain any references to health information or request health information from the subject through email.
• The University of Wisconsin-Madison allows researchers to use email to send its faculty, staff, and students information about research opportunities. Information about the campus mass email service is available at: Mass Email – Getting Started .

For additional information about using email in research, please see the general communication guidelines section .

In addition to the general recruitment guidelines, these guidelines apply to research studies that identify potential participants from the electronic health record or will identify and recruit participants in a clinical health care setting (i.e., patients). The guidelines apply regardless of the reviewing IRB. Other healthcare entities outside of UW/UW Health may have additional guidelines or policies that apply.

• A member of the potential participants’ clinical team, and those individuals working on behalf of members of the clinical team (e.g., nurses, PAs, pharmacists);
• An administrator from the clinic, department or center where the potential participant receives care;
• An individual, such as a study nurse, investigator, or research coordinator, acting as an agent of a clinical researcher involved in the potential participants’ care;
• An individual, such as a study nurse, investigator, or research coordinator, who works within a clinic, department, or center where a potential participant has or will receive care (e.g., from the Department of Surgery for a patient who has an upcoming surgery scheduled);
• The administrator of a database housed within a clinic, department, or center where a potential participant has or will receive care (e.g., from a recruitment database or registry within the department or clinic where the patient has been seen for clinical care).
• “Cold calling” of potential participants by phone is generally not permitted. “Cold calling” is a planned communication with a potential participant by the study team when not known to the potential participant or not expected to have access to their protected health information.
• The IRB generally requires telephone calls to be preceded by a letter that alerts potential participants that they will be called about the study. The letter should provide contact information for the individual to opt-out if they do not want to receive a phone call or further contact.
• Phone calls for studies that fall under VA purview must be preceded by a recruitment letter because VA regulations do not permit cold calling, unless there is prior written documentation that the potential participant is willing to be contacted by phone.
• Use of patient email addresses in HealthLink for research recruitment is not permitted.
• Use of MyChart for recruitment purposes is permitted if conducted with approval from UW Health and the IRB.
• How and who initiates contact with patients in a clinical setting depends on the circumstance. Any patients in private clinic rooms or hospital rooms should first be approached by someone who is part of their care team or an administrator who is part of the clinic or department in which the study is being conducted.
• Researchers who are employees of the covered entity or members of its workforce for research purposes (e.g., members of the UW/UW Health Affiliated Covered Entity when accessing PHI from Health Link) may use PHI to recruit participants as a preparatory to research activity .
• For all other researchers, the IRB may grant an altered authorization to permit an abbreviated written authorization or to permit an oral authorization process (see suggested template language below). Permission to Contact template language: The HIPAA Privacy Rule requires this clinic to get your permission to release your name and phone number to Dr. _______ and his/her research team at the University of Wisconsin-Madison so that they can contact you about taking part in this study. Your information will only be used for this purpose and not be shared with anyone other than the UW research team. If you decide to provide your name and contact information, you can still decline to participant in the research study. You do not have to give your name and contact information if you don’t want to. If you don’t want to provide your name and contact information, it will not affect your health care at this clinic.
• Recruitment of potential participants in waiting areas or other similar space requires permission from the institution or clinic to ensure minimal interruption of workflow.

Studies using Oncore and with a study record in Health Link may be eligible to recruit subjects through MyChart, UW Health’s patient portal. Study teams should describe this as a recruitment modality in IRB application materials and include invitation language using the approved UW Health invitation template (see below). Note, while IRB approval to recruit through MyChart is a requirement, study teams must also comply with UW Health requirements for such MyChart use. Please see MyChart Recruitment FAQs for UW Health requirements and information on the process for obtaining approval and submitting a request.

Study teams should consider the following in determining whether MyChart is an appropriate recruitment modality for a given study:

• Sensitivity of the research . Many patients allow proxy access to MyChart. Any recruitment invitations would be visible to both the patient and any proxies to whom they have granted MyChart access. Study teams should consider whether this creates a confidentiality concern.
• Adequate study population with MyChart Access . Only a subset of UW Health patients actually use MyChart. Study teams should consider whether this will unintentionally limit diversity of recruitment and potentially impact generalizability of data.

Once UW Health and IRB approvals are in place, study teams will submit a recruitment request through the Clinical Research Data Services (CRDS). CRDS will assist in determining whether there is an adequate study population with MyChart access and if so, identify potentially eligible subjects based on parameters provided by the study team. Only those patients identified through CRDS can receive a research study invitation through MyChart.

The following is suggested language study teams may use to describe the use of MyChart recruitment in IRB materials:

One recruitment modality we plan to use is MyChart, UW Health’s patient portal. We will obtain all needed approvals from UW Health and the Clinical Research Data Service and follow the required workflows. We will/have create(d) an OnCore study record that is interfaced with Health Link and will track individual level recruitment in OnCore. Once approvals are in place, the IRB-approved invitation will be posted to invited participants’ Research Studies page in MyChart and patients will initiate contact with study team if interested.

The following patient-facing invitation language should be edited by study teams and included in IRB materials:

Bold text in brackets to be filled in by study team.

You are invited to participate in a research study: [ Patient-facing Title of Study ]. The lead researcher is [ Principal Investigator name and credentials ] with [ Principal Investigator’s affiliation/department ].

The purpose of this research study is [ Brief Description ].

If you are interested in participating or have questions about the study, please click on the “I’m interested” button below and a study team member will reach out to you, or you may contact the study team at [ Information on how to contact study team ].

How to opt out of receiving messages about this research study If you are not interested in participating and you would no longer like to receive MyChart messages about this study, please click on “No, thank you” below.

How to opt out of receiving recruitment messages for any or all research studies If you would no longer like to receive messages about research opportunities at UW Health, please call the UW Clinical Trials Institute at 608-265-3132 . You will be asked for your information such as name, date of birth and address so we can make sure you are added to the list of patients who do not want to receive research recruitment messages. This information will be stored in a secure location.

If you opt out of receiving messages about research opportunities, your health care team may still contact you about clinical research for which you might be eligible.

• It is the responsibility of the research team, when designing a protocol, to understand the social media site terms of use. In addition, study teams should be aware of any research or recruitment-related restrictions on the social media sites through which they intend to conduct their recruitment activities. This includes a site’s advertising, privacy and prohibited content policies.
• It is the responsibility of the research team, when designing a protocol, to understand the various privacy and data security provisions of social media sites and ensure that these provisions are consistent with the IRB’s privacy and confidentiality guidelines.
• In social media or other Internet-based research settings, recruitment information can be forwarded or otherwise accessible to other individuals who may not be part of the intended participant pool. Research teams, therefore, must exercise caution to appropriately identify the targeted participant population and to ensure the equitable selection of participants.
• The IRB will review the content of social media recruitment materials according to existing IRB guidelines for traditional media recruitment such as flyers and news ads.
• Recruiting via public and private groups is permitted. Study teams must be aware of any site restrictions or group-specific rules or restrictions on recruiting participants via groups.
• Study teams are discouraged from using their personal social media accounts to purchase or place initial recruitment materials for studies.
• Collection of identifiable private information to determine study eligibility is considered a research procedure. Obtaining oral permission prior to the research screening interview is usually acceptable.
• For HIPAA Privacy Rule purposes, telephone screening may constitute a preparatory to research activity. See Preparatory to Research Activities in this manual. However, the VA interprets preparatory to research differently than the UW-Madison. Telephone screening for VA research studies requires a partial waiver or alteration of authorization.
• In most cases, screening information from individuals who take part in the study is kept as part of study records, while screening information from individuals who are not eligible or choose not to participate is destroyed. Researchers proposing to retain contact information and/or identifiable data collected during telephone screening for future recruitment or other purposes should specify what information will be retained, and how long, how the information will be stored, how the information will be used, and who will have access to the information. In addition, researchers will need to either obtain informed consent and authorization (for studies that fall under HIPAA regulations) from subjects to retain the identifiable screening data or request waivers of informed consent and authorization from the IRB.
• Retention of sensitive screening information from subjects who are ineligible (e.g., data about illicit or stigmatizing behavior; social security numbers) is discouraged.
• The investigator will obtain information through oral or written communication with the prospective subject or legally authorized representative, OR
• The research protocol should include information about how potential subjects will be identified and recruited in order for the IRB to be able to determine whether informed consent for these activities is required.
• Contact the IRB Office with additional questions or for further guidance regarding the requirement to obtain HIPAA authorization or a waiver to obtain HIPAA authorization for recruitment purpose.

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15 clinical trial patient recruitment companies (and how to choose one).

Updated July 2022: 

Clinical trial patient recruitment companies make use of many methods, including digital advertising and community partnerships, to find the right patients for your trial. Depending on the trial your organization is running, it may be advantageous to pick a company that has a specialized focus in a therapeutic area or patient population. You may want to also consider finding a company that offers multiple services in addition to patient recruitment, such as custom prescreeners or site identification. 

When it comes to picking your recruitment partner, make sure to think through each company’s offerings and experience in the area you will be researching. Below, we have included some questions to ask a potential vendor, in addition to an overview of how clinical trial recruitment companies can help solve common challenges involved with finding study participants.

15 clinical trial patient recruitment companies

These 15 clinical trial recruitment companies are some of the best in the business. Read a bit about each to determine who is the ideal fit for implementing clinical trial recruitment strategies for your organization.

• Antidote : Antidote’s mission is to connect sponsors and research sites with informed, engaged patients who are interested in participating in a clinical trial. Services include validated referrals, customized outreach plans, access to a 300+ nonprofit and patient advocacy partner network , and other premium services for trial sponsors.
• AutoCruitment : AutoCruitment makes use of more than 1,500 digital channels to connect with patients searching for medical information online. It is also known for its speed and advertises a three-day setup time.
• BBK Worldwide : With over 30 years of experience in patient recruitment, BBK Worldwide has a vast library of whitepapers and ebooks to share what they have learned throughout the years. 
• Clariness : Clariness is an internationally focused recruitment company that has enrolled patients in more than 1,000 trials in 50 countries .
• ClinicalConnection : ClinicalConnection works with a database of patients and also features study centers on the website for potential participants to find.
• CSSi : As part of their patient recruitment strategy, CSSi connects with local patient organizations to find eligible participants.
• Curavit : With decentralized clinical trial execution, Curavit specializes in connecting with patients via telehealth and trial technology platforms.
• Elligo Health Research : Elligo Health Research has a time-tested “Elligo Direct” approach that makes it simple for physicians and their patients to take part in clinical trials.
• Langland : An advertising agency with branding and clinical trial marketing expertise, Langland is able to blend patient, protocol, disease, and media insights with data and technology to provide recruitment and retention solutions.
• MMG : With several decades worth of experience, MMG refers to itself as a team of global recruitment strategists and emphasizes its strategy support capabilities.
• Praxis : By offering a range of service options , Praxis allows customers to pick and choose what they need, from digital advertising to community outreach.
• Science37 : A technology-focused company, Science37 is a virtual clinical trials company that can provide full trial execution or supplemental technology in addition to change management services.
• StudyKik : After seeing advertising for the service across Facebook and other platforms, potential participants can sign up for Studykik and be notified when a trial is created for which they may be eligible.
• TrialSpark : By partnering with physicians and pharmaceutical companies, TrialSpark reduces the time and expense of clinical trials by providing technology, equipment, and staffing.
• TrialX : In addition to patient recruitment services, TrialX also creates mobile apps for trials.

What to consider before choosing a clinical trial recruitment company

When picking a company for clinical trial recruitment, be sure to consider what each one offers and their experience in your specific therapeutic area. Below, we have listed some questions that companies can ask themselves to determine which clinical trial recruitment partner is right for them .

Do you need help picking site locations for the trial? If you have not yet decided on the site locations for your trial, it may be helpful to consider working with a company that will assist with this part of the process. Many companies can use data from previous trials to identify the best locations and have a deeper understanding of ones that might prove difficult in terms of recruitment.

Are you proactively seeking recruitment support, or are you looking for “rescue” recruitment? Some companies specialize in recruitment support for specific parts of a trial. If your trial has already begun and has failed to achieve good patient enrollment numbers, a company that focuses on speed and efficiency may be ideal . If you’re proactively looking for assistance, you will likely be better off choosing a company that can provide strategic planning and guidance for the full breadth of the trial. What budget model are you looking for in the trial? There are a range of budget options offered by clinical trial recruitment companies, such as paying for performance or negotiating a flat fee. It’s smart to think through your trial’s budget and how you want to structure your payments so you can discuss this with potential vendors. Does the company have an in-house marketing team? Collaborating with a company that has an experienced, internal marketing team is a great way to get online advertisements that stand out among cluttered social media and digital feeds. When you talk to potential companies, it’s smart to ask how they develop their marketing materials and if you can review previous campaigns they have run .

Does this company have experience in my therapeutic area? Location, inclusion criteria, and the protocols of a trial can heavily influence participation rates, but if a company has recruited in a specific area before, they should have a good sense of what tactics do and don’t work for recruiting in a certain space. Working with a company that has operated in your therapeutic area before can give you access to these vital insights, and you can often ask for case studies to see examples of their past results .

Does the company specialize in a particular phase of trials? Some recruitment companies will have expertise in specific phases of clinical trials , which can be helpful depending on your needs. Depending on what phase your trial is at, choosing a company experienced with healthy Phase 1 volunteers can be ideal, while companies experienced with Phase 4 can be great if you need ongoing research and observation.

Has this company worked on international trials before? If you are using trial sites in multiple countries, it can be helpful to work with a recruitment company with international experience. This can be useful if you need translated materials or assistance creating ad strategies to recruit non-U.S. participants.

How does this company handle ineligible patients that may be able to participate in my other trials? Some recruitment companies maintain a database of patients that have shown interest in trial participation and can recruit from that database. For example, at Antidote, we offer the option to match patients from our database with any trial in your portfolio so potential participants are not lost in the shuffle. 

What is the lead time for developing materials and a recruitment strategy? Many companies will advertise their recruitment speeds to potential customers, so if you are on a tight deadline, this can be helpful for getting things started in a timely manner. 

How will patients be screened? Some recruitment companies can also handle creating and hosting a custom prescreener for your trial, in addition to executing patient phone screening. It’s helpful to think through whether or not you would find these services useful when choosing a recruitment partner.

How does the company handle lackluster recruitment results? There are many challenges surrounding clinical trial recruitment, and roadblocks to patient enrollment are common. Inquiring about how the company handles these challenges can let you know how to expect them to amend their strategy if recruitment isn’t going as well as they had hoped.

Am I looking for both patient recruitment and retention? Once a patient is enrolled in your trial, it is important to consider what effort will be made to retain them. Some recruitment companies provide services designed to help your trial continue running on schedule, even after the recruitment goal is reached. Tools can range from engagement programs to technology that assists with collecting patient data to follow-up services at the site.

What types of reporting would you like to receive from the company? When in talks with your potential vendor, it can be wise to ask how often they update clients on recruitment metrics and any other insights into the campaign’s performance. Often, you can request a sample report to review what the company typically shares with its clients and how often.

What is the company’s relationship with patients? Patient centricity starts with the initial research design and continues to be important throughout a trial. Inquire with potential vendors on any feedback they’ve received from patients on advertising campaigns or other elements of the recruitment process. It is smart to look for a company that is focused on creating patient materials that are clear, readable, and contain essential information to help patients determine if the trial is a good fit.

What diversity efforts are involved in patient recruitment? It is important that clinical trials accurately reflect the population, so making efforts toward recruiting a diverse and varied population is a key consideration. Talk with potential vendors about how they are approaching diversity initiatives , especially if your therapeutic area disproportionately impacts a certain patient population.

How does the company find patients to participate? Recruitment vendors have a whole host of techniques at their disposal to find patients (see below), but your organization may also have a preference for how patients are engaged. For example, if you are doing research surrounding a rare disease, it may be beneficial to work with a company that has partnerships with organizations that focus on that condition. When assessing a company, be sure to ask questions about what approaches they have found most effective.

Clinical trial patient recruitment challenges

Patient recruitment companies can help solve common challenges that are often encountered during a recruiting campaign. Whether you approach a recruitment company before you begin trial recruitment or utilize them for a "rescue study," they can be great resources for handling these challenges — and having a general understanding of how to recruit patients for clinical trials can help you be sure you’re asking the right questions when meeting with potential vendors.

Challenge: You’re getting referrals for patients that aren't eligible for the trial.

Solution: Diversify your patient recruitment approach.

Nearly 85% of clinical trials struggle to recruit enough patients , and some fail to enroll a single patient. Unforeseen issues, such as inaccurate patient data or competition from other nearby clinical trials, can pop up even with an effective site selection process in place.

By diversifying your approach to patient recruitment early on in the process, you can set your trial up to reach (or even beat!) its recruitment timelines. Working with a clinical trial patient recruitment company can be beneficial even before a trial has begun to fall behind.

Challenge: Research sites are underperforming.

Solution: Collaborate with a recruitment company with access to specific and accurate data.

As medical knowledge has developed, clinical trials have become more complex. For example, many researchers require participants to have specific lab values or markers, which is information patients often do not know on their own. Specifics like this can often result in more screenfailing of patients, which can lead to recruitment delays.

One way to tackle the issue of complex eligibility requirements is by working with a recruitment company that has patient data that reaches beyond a diagnosis. Patient medication, results from recent bloodwork, and other key markers can give researchers valuable insights into the likelihood of a patient’s eligibility. For example, key partnerships such as Antidote partnering with PWN allow us to provide trial sponsors with lab-validated patient referrals.

Challenge: Patients become unresponsive before they ever reach your research sites.

Solution: Get support on patient and site follow-up.

Even for patients who are very interested in participating in a clinical trial, there are plenty of factors that can result in a loss of contact. Missed communications, a lack of availability for screening, and other issues can result in your trial losing the patient between initial contact to randomization.

Contacting interested patients and performing site screenings keep trial staff busy as is, so finding time to follow up with patients who have disengaged often falls by the wayside. A recruitment agency can often provide site and patient follow-up services, which can help retain patients and move them to the next step in the screening. Automated follow-ups and rescheduling opportunities can reduce site time and move patients forward in the process, in addition to obtaining valuable information if the patient’s cancellation was intentional.

Challenge: The patients you find live too far from your sites.

Solution: Offer travel services and adjust your targeting.

There are several things that will impact how far study participants are willing to travel to participate in a trial, such as the frequency of visits and how symptoms impact a patient’s mobility. If you are finding patients that live too far away from your research sites, the first thing to do is to get in touch with the site or recruitment company conducting your outreach to see if you can reduce the radius of your targeting. You may also want to consider providing travel services or reimbursement for patients that do live farther away in order to better incentivize their participation.

Challenge: There is a lack of interest in your trial, even after outreach efforts are made.

Solution: Collaborate with a recruitment company that has more experience with the condition you are researching.

While every patient is different, the research that has been conducted on clinical trial participation can show us some common themes. Patients are generally motivated towards trial participation as a way to give back and help research, but in a patient survey Antidote conducted, it was revealed that motivations can vary widely depending on the condition in question. For example, we found that asthma and allergy patients rated receiving payment as influential in their decision to participate. 

If your current outreach methods are not leading to strong participation numbers, it may be because the interests of your patient population are not being reflected. Working with a company that has experience recruiting for a range of conditions can ensure you are distributing effective outreach materials that resonate with patients who have specific reasons to be interested in participating in a clinical trial.

What clinical trial recruitment strategies do agencies use?

Finding the right patients to participate in research typically requires the use of multiple clinical trial recruitment strategies . Some recruitment providers may specialize in a specific approach, but most companies will employ an array of strategies to connect with patients . The clinical trial recruitment process may include:

Digital advertising: Utilizing Google Ads, Facebook, and other social media ad platforms allows recruiters to target users with specific interests that relate to a trial’s inclusion criteria, in addition to targeting people who are searching for clinical trial opportunities. Additionally, website ad placements allow a company to target users based on the pages they are visiting, which may indicate their interest in a clinical trial.

Traditional advertising: Traditional ad placements can range from radio ads to billboards to print materials distributed at doctor’s offices.

Patient databases and registries: Some clinical trial recruitment companies maintain a database of patients who have shown interest in clinical trial participation and can alert patients when there is a trial in their area that may be a good fit. Not only does this benefit your trial by increasing its potential reach, but companies that have these databases often offer a lower cost-per-patient price compared to the companies that are doing all of their outreach from scratch.

Partnerships: Clinical trial recruitment companies may have partnerships with nonprofits and community groups that are associated with a particular condition, which can be especially helpful when these partners have robust email lists. By leveraging these partnerships, recruitment companies can reach a group of motivated, qualified patients in a streamlined way.

Electronic Health Record (EHR) matching: There are companies that offer software to integrate medical record review into recruitment, which is beneficial for several reasons. Because health records often indicate lab tests, recent treatments, and more, EHR matching can make it easier to identify patients who may be eligible for the trial. It also allows physicians to easily alert their patients about potential clinical trial opportunities — plus, if patients have heard about the trial from a trusted source, such as their doctor, they may be more likely to show interest in participating.

Community events: Companies that have partnerships with nonprofits and other organizations will often attend local health fairs or other related events and can promote your trial there via flyers, pamphlets, and other advertising materials.

Learn about how Antidote has helped sponsors connect with our community of patients by downloading our case studies.

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• Open access
• Published: 16 October 2014

Interventions to improve recruitment and retention in clinical trials: a survey and workshop to assess current practice and future priorities

• Peter Bower 1 ,
• Valerie Brueton 2 ,
• Carrol Gamble 3 ,
• Shaun Treweek 4 ,
• Catrin Tudur Smith 5 ,
• Bridget Young 6 &
• Paula Williamson 5  

Trials volume  15 , Article number:  399 ( 2014 ) Cite this article

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Despite significant investment in infrastructure many trials continue to face challenges in recruitment and retention. We argue that insufficient focus has been placed on the development and testing of recruitment and retention interventions.

In this current paper, we summarize existing reviews about interventions to improve recruitment and retention. We report survey data from Clinical Trials Units in the United Kingdom to indicate the range of interventions used by these units to encourage recruitment and retention. We present the views of participants in a recent workshop and a priority list of recruitment interventions for evaluation (determined by voting among workshop participants). We also discuss wider issues concerning the testing of recruitment interventions.

Methods used to encourage recruitment and retention were categorized as: patient contact, patient convenience, support for recruiters, monitoring and systems, incentives, design, resources, and human factors. Interventions felt to merit investigation by respondents fell into three categories: training site staff, communication with patients, and incentives.

Conclusions

Significant resources continue to be invested into clinical trials and other high quality studies, but recruitment remains a significant challenge. Adoption of innovative methods to develop, test, and implement recruitment interventions are required.

Peer Review reports

There is currently a worldwide drive to enhance health, wellbeing, and wealth through effective research and dissemination. In the United Kingdom, the overarching vision of the National Institute for Health Research (NIHR) is to see ‘more patients and health professionals participating in health research’ [ 1 ].

A critical part of the health research portfolio is the testing of interventions through randomized controlled trials. Trials can range from highly controlled explanatory trials through to pragmatic trials of new health technologies and models of service delivery. A large number of trials are dependent on the willingness of patients and professionals to give their time and effort to participate. If high levels of participation (through recruitment to the study and longer-term retention) are not achieved, this has implications for statistical power, internal validity, and external validity. Recruitment problems also have practical and financial impacts, as they can delay completion of research or reduce its timely impact on patient health and wellbeing.

Achieving appropriate levels of patient and professional participation has been a significant obstacle to evidence-based practice. Published data show that the minority of trials recruit successfully, either in terms of reaching their planned sample size, or delivering the planned sample in the expected recruitment window [ 2 , 3 ]. Although there may have been improvements since these initial surveys, related in part to the significant investment in infrastructure [ 4 ], problems still remain [ 5 ]. A recent survey of Clinical Trials Units (CTUs) in the United Kingdom conducted by the some of the authors [ 6 ] found that recruitment remained the number one priority of those units.

A recent review outlined three core areas of relevance in improving recruitment and retention: infrastructure (for example networks, resources, and information technology), professional and public engagement with research, and methodological innovation (the development of an evidence base around effective methods of recruitment) [ 7 ]. This current paper is designed to provide an overview of the current knowledge and practice in the area of methodological innovation, in order to set out a clear research agenda for the future.

Methodological innovation

Many insights into the recruitment and retention process have been generated from qualitative case studies conducted alongside existing trials [ 8 – 11 ], as well as research on hypothetical situations [ 12 , 13 ]. However, translating those insights into enduring and generalizable impacts on recruitment is not straightforward. Although this may be due to other limitations in the academic literature (such as the lack of robust theory to guide intervention development), the limited impact of this work may in part reflect the fact that these (essentially post hoc ) explanations of recruitment processes are rarely subjected to formal examination in prospective studies. From the perspective of the principal investigator struggling with recruitment problems, this research has generated hypotheses to be tested rather than proven levers to ease recruitment.

The most robust test of the effectiveness of a recruitment or retention method is a trial comparing one recruitment method with an alternative, ‘nested’ within an ongoing trial being conducted in routine settings. By ‘nesting’, we refer to patients being randomly allocated to two or more alternative methods of recruitment. For example, a published study randomly allocated patients to an opt-in (where they were asked to actively signal willingness to participate in research) or opt-out method (where they were contacted repeatedly unless they stated unwillingness to participate) [ 14 ]. Such studies allow a less biased and more externally valid assessment of the effectiveness of a recruitment intervention. Nevertheless, despite the vast amount of activity in the area of clinical trials, nested studies of recruitment interventions remain very rare [ 15 – 17 ].

In this paper, we draw on a number of sources of data (including existing reviews on recruitment and retention interventions, survey data from CTUs in the United Kingdom, and views of participants in a recruitment workshop) to meet the following aims: to summarize knowledge about interventions to improve recruitment and retention, to indicate the range of interventions used by CTUs in the United Kingdom, to present a priority list of recruitment and retention interventions for evaluation, and to consider wider issues concerning the testing of recruitment interventions.

Summary of current knowledge on recruitment and retention

Interventions to improve recruitment have been the focus of a number of systematic reviews. A Cochrane review collated randomized and quasi-randomized controlled trials of interventions to increase recruitment to trials, including those recruiting to hypothetical studies [ 15 , 16 ]. The review included 45 trials involving 46 interventions and over 43,000 participants. Some interventions were effective in increasing recruitment, such as telephone reminders to non-respondents (risk ratio (RR) 1.66, 95% CI 1.03 to 2.46), use of opt-out rather than opt-in procedures for contacting potential participants (RR 1.39, 95% CI 1.06 to 1.84), and open designs whereby participants know which treatment they are receiving in the trial (RR 1.22, 95% CI 1.09 to 1.36). A substantial problem noted by the reviewers was the tendency for investigators to evaluate new interventions that are unlike earlier interventions, making pooling data difficult. This has resulted in a large pool of relatively unique recruitment interventions of uncertain benefit. Other reviews [ 18 , 19 ] came to similar conclusions, although one review found no evidence that strategies aiming to increase understanding of the trial process improved recruitment, but did find some support for strategies that increased understanding of the health problem being studied [ 18 ].

Fletcher et al . [ 20 ] focused on strategies aimed at increasing the recruitment activity of clinicians and found eight quantitative studies, only three of which were trials. One trial looked at the effect of using nurses rather than surgeons to recruit participants and found that this had little or no effect (RR 0.94, 95% CI 0.76 to 1.17), though it was more cost-effective. There was limited evidence that greater communication between central trial coordinators and trial sites, and on-site monitoring had no impact on recruitment. The use of qualitative methods to identify and overcome barriers to clinician recruitment activity appeared promising, although the picture was mixed, with impressive improvements at one centre and no or modest improvements at others. The approach is certainly worthy of further investigation. A Cochrane review of incentives and disincentives to participation in trials by clinicians found no trials of relevant interventions [ 21 ]. The impact of a number of potential (dis)incentives was explored in observational studies but none were shown to have a significant impact. The authors suggested that in the absence of robust evidence, researchers need to be aware that many aspects of trial design and conduct might affect clinicians’ willingness to invite patients to participate.

In summary, there are some promising strategies for increasing recruitment to trials. However, some of those methods (such as open-trial designs and opt-out strategies), must be considered carefully as their use may also present methodological or ethical challenges. Use of qualitative methods to explicitly identify and address barriers to participation appears promising and warrants greater evaluation. There is a clear knowledge gap with regard to effective strategies aimed at recruiters.

Retention strategies have been the subject of three systematic reviews. Most of the retention strategies evaluated have focused on improving response to postal or electronic questionnaires, rather than return to trial sites to complete face-to-face assessments. A Cochrane systematic review on methods to increase response to postal and electronic questionnaires included 513 trials, with 137 strategies identified [ 22 ]. The most effective strategies to improve postal questionnaire response were: monetary incentives (odds ratio (OR) 1.87, 95% CI 1.73 to 2.04), recorded delivery (OR 1.76, 95% CI 1.43 to 2.18), a teaser on the envelope (OR 3.08, 95% CI 1.27 to 7.44) and having a more interesting questionnaire topic (OR 2.00, 95% CI 1.32 to 3.04). Other communication and questionnaire modification strategies found to be effective were: including pre-notification reminders, follow-up contact with participants, shorter questionnaires, and providing a second copy of a questionnaire. Several effective strategies for increasing responses to electronic questionnaires were found which included: including a picture in an email (OR 3.05, 95% CI 1.84 to 5.06), non-monetary incentives (OR 1.72, 95% CI 1.09 to 2.72) and other communication, and motivational and electronic questionnaire strategies. However, mentioning ‘Survey’ in the email subject line (OR 0.81, 95% CI 0.67 to 0.97), and emails including a male signature (OR 0.55, 95% CI 0.38 to 0.80) reduced the odds of a response. An earlier systematic review also focused on ways to increase the response to postal questionnaires in healthcare research [ 23 ]. A total of 15 trials were included in this review. Reminder letters (OR 3.7, 95% CI 2.30–5.97) and shorter questionnaires increased response (OR 1.4, 95% CI 1.19 to 1.54). Monetary incentives were not found to be effective.

These reviews were broad and included nested evaluations of strategies to improve retention in surveys, cohort studies, and randomized trials. Although some of the included trials in the reviews were nested in trials, most were nested in other study designs and the results may not be directly applicable to trials. A recent systematic review examined the effectiveness of strategies to improve retention in randomized trials specifically, and found 38 trials that evaluated six different types of strategies [ 17 ]. Most of the included trials aimed to improve questionnaire response. Questionnaire response was improved by actually adding monetary incentives (RR =1.18, 95% CI 1.09 to 1.28), the offer of monetary incentives (RR =1.25, 95% CI 1.14 to 1.38), and higher value incentives (RR =1.12, 95% CI 1.04 to 1.22). Based on results of single trials, response was improved by recorded delivery of questionnaires (RR =2.08, 95% CI 1.11 to 3.87), a specialized postal strategy (RR =1.43, 95% CI 1.22 to 1.67) and an open-trial design (RR =1.37, 95% CI 1.16 to 1.63). There is no clear evidence that questionnaire response or retention were improved by any of the other incentives, questionnaire modification, and communication strategies evaluated including the giving or offering gifts, offering charity donations, shorter or longer and clear questionnaires, sending questionnaires early, ‘enhanced’ letters (i.e. letters which contained additional information about trial processes or which included novel features, such as the signature of the main investigator), priority post, additional reminders, questionnaire question order, reminders to sites, and behavioral or case management strategies.

In summary, offering and giving small monetary incentives improves questionnaire response in randomized trials, while non-monetary incentives and some communication strategies have shown no effect. Some strategies need further evaluation, particularly where the results are based on single trials.

In the United Kingdom, funding bodies increasingly require that trials involve a United Kingdom Clinical Research Collaboration registered CTU to ensure high quality delivery and appropriate support with ethical, governance, operational, and methodological issues. Due to their active involvement with multiple trials, CTU staff are potentially in an excellent position to provide an overview of current methods used to stimulate recruitment and retention.

In order to provide data on current practice, 48 CTU directors in the United Kingdom were sent an invitation to an online survey about the methods and practices currently used by CTUs to improve recruitment and retention. Directors were asked to identify a member of staff best placed to provide responses on behalf of the unit. Where more than one member of staff from the same CTU completed the survey, similar responses were combined to ensure that responses from the same CTU were not counted twice. Respondents were asked about the methods used to improve recruitment and retention (with or without formal evaluation), methods which had been formally evaluated, and recruitment and retention interventions thought to merit evaluation in the future. The full list of questions is provided in Additional file 1 . Two reminder emails were distributed to encourage responses from all CTUs.

The results from the CTUs survey were used to inform a workshop on interventions to improve recruitment and retention, organized by the Medical Research Council North West Hub for Trials Methodology Research on behalf of the Medical Research Council Hub for Trials Methodology Research Network. Attendees at the workshop (n =45) were predominantly staff from CTUs (approximately 80%), as well as researchers outside CTUs, and representatives from funding agencies from the United Kingdom. Data from existing Cochrane reviews (summarized previously) were used alongside data from the survey to generate discussion around recruitment interventions. The final part of the workshop was used to generate further priorities for evaluation. Participants were split into small groups and asked to reflect on the data from the survey and the reviews, and to develop a priority list of interventions that would potentially improve recruitment and could be subjected to empirical testing. Groups reported back at the end of their discussions on both the nature of those interventions and their priority order, and the results were categorized by the workshop leader (PW). As the survey and workshop used professionals and involved discussions of current practice, no formal ethical approval or consent was deemed necessary.

Responses were received from 23 individuals representing 18 CTUs (38%). Respondents included statisticians, trials managers, health researchers, and research nurses.

Current recruitment and retention interventions

Table  1 shows the methods routinely used to encourage recruitment and retention, which were coded into the following categories: patient contact, patient convenience, support for recruiters, monitoring and systems, incentives, design, resources, and human factors. These broadly map onto the categories of recruitment interventions found in the recent Cochrane review discussed previously [ 15 ].

Patient contact interventions in recruitment related to appropriateness of the materials and the range of ways of getting information to patients, whereas retention was more focused on the number of contacts with patients. Both recruitment and retention interventions highlighted ways of reducing burden on patients, although it is not clear that research burden is necessarily the main barrier to participation. A large number of systems and monitoring interventions were discussed, to expand the range of methods used to identify patients, and to enable participants to be identified in the longer term as the trial progresses. Incentives included a wide range of potential interventions, such as direct payment for recruiters, patient expenses and gifts, and secondary incentives such as authorship on papers for staff involved in recruitment. Design issues were most often discussed in relation to recruitment, and included initial appropriateness of the design, the importance of pilot and feasibility studies, as well as flexibility in response to difficulties of recruitment. Respondents highlighted the importance of relationships in both recruitment (with the focus on relationships between the research team and recruitment staff) and retention (in terms of building and maintaining relationships with patients).

Table  2 describes interventions felt to merit investigation by respondents, in three categories: training site staff, communication with patients, and incentives. Some of these areas have been assessed in existing reviews, for example, site visits and intensive communication have been the subject of two studies with a published review, with little demonstrable effect on recruitment [ 20 ]. It is noteworthy that the impact of patient and public involvement was raised in two themes, given recent observational research suggesting an association between patient involvement and recruitment success [ 24 ]. Although the use of patient and public involvement is likely to be too embedded in current research to test its impact compared with an absence of involvement, exploring the relative benefits of different types of patient involvement, or different levels of resourcing of involvement is still likely to be of benefit to the research community.

Priorities for evaluation - results from the workshop

The results from the CTUs survey were used to inform a workshop on interventions to improve recruitment and retention, using small group work to generate further priorities for evaluation. Table  3 details the results of the small group work. The top priority identified was training for site staff, followed by different methods of communication with patients. The following sections provide more information about the potential priorities within those areas that were generated at the workshop and through follow-up teleconferences among workshop participants.

Training site staff

Many trials involve direct communication between patients and recruitment staff, and there is variability in the ability of staff on the same trial to achieve high levels of recruitment, with some studies reporting high levels of recruitment from a minority of practitioners [ 25 ]. This may reflect factors other than differences in their patient populations, such as variation among staff in the perceived importance of the study question, or different attitudes to equipoise. Identification of the characteristics of staff associated with recruitment and retention success could lead to a better selection of staff, while comparison of staff with different levels of recruitment success within the same trial might provide insights into effective components of training which could be developed into relevant training packages prior to formal evaluation. Such development will need to take into account the current debates concerning the ethics around coercive communication [ 26 , 27 ]. There is also an interesting empirical question concerning the relationship between strategies that enhance recruitment, and effects on retention, as there is the possibility that encouraging ambivalent patients into studies may lead to short-term gains in recruitment, and longer term challenges in retention. The need to evaluate different models of verbal communication (for example empathic communication versus information provision) and to gain evidence of whether changes to recruiter communication behaviour leads to benefits for patients beyond recruitment rates (for example, improved satisfaction with the recruitment process and perceptions of shared decision-making) were also identified. Emphasis was placed on understanding patient priorities at the time of recruitment and how these may change over time to aid retention [ 28 ].

The relevant impact of generic communication skills versus specific skills around particular issues is an important issue. For example, discussions around patient preferences are known to be a major potential barrier to trial participation [ 29 ] and specific training in managing those discussions might be more fruitful than generic interventions, especially in certain contexts where preferences are particularly important [ 28 ]. However, studies continue to show problems in the core aspects of communication [ 30 ]. Another important issue is whether training should be provided at the start of any trial, for all recruiters, or whether it is more feasible and efficient to identify staff with low recruitment rates and intervene later, potentially following detailed qualitative work to identify the precise nature of the problems [ 31 , 32 ].

Methods of communication with patients

As noted, the focus of much of the discussion around training site staff was around the issue of face-to-face communication, whereas this theme related more to different types and platforms for communication with patients, and the balance between face-to-face discussions, other forms of providing information to patients [ 33 ], and wider interventions related to shared decision-making [ 34 ]. The use of technology for communication was highlighted in particular for recruitment in trials where the initial recruitment is not via a face-to-face consultation (such as community-based trials among patients with existing conditions recruited initially by postal or other methods). Technology was also considered to be an area that could assist with the retention of participants over time, both through effective tracking of patients and methods used to enhance motivation to continue participation (such as reminders and updates about trial progress).

Given the dissatisfaction among patients and staff over the potential length and burden associated with standard patient information sheets, technology would also potentially provide flexible and patient-centered methods to provide information in appropriate depth according to patient preference (as long as it meets minimum criteria as set by ethical and regulatory bodies) [ 35 ].

As noted in Tables  1 and 2 , a wide range of potential interventions acting as incentives are in use and of interest to staff currently involved in the recruitment to trials, but the evidence base is limited [ 10 , 21 ]. In relation to patients, this may include payment for time taken to participate (which might not be viewed formally as an incentive, although it might have motivational benefits), small gifts and payment for incidental expenses, as well as formal cash or voucher incentives for participation and retention. However, the scope for testing such incentives through formal experimental methods may be limited by ethical and equity considerations.

Issues of incentives can also be applied to professionals, although the scope here may be greater, as potential incentives could be indirect (such as authorship on papers). There may also be greater potential for experimental work in the testing of the comparative effectiveness of schemes which provide differential incentives for different recruitment staff, teams, or sites depending on their relative performance (per patient recruited incentives versus block payments for meeting targets).

What is needed to facilitate rapid testing and development of interventions?

Although there was agreement about the need to conduct research on recruitment, the actual number of recruitment interventions nested within existing trials is very small [ 15 ]. Research has highlighted some of the known barriers to undertaking such research [ 36 ] such as increases in complexity, compatibility between the host trial where the recruitment research is done and nested trials (for example, the relevance of certain recruitment interventions to certain patient populations), the impact of nesting interventions on relationships with collaborators, as well as issues of preferences among research staff (and resulting lack of equipoise), and concerns about appropriate sample size.

Data on these issues were also collected from the CTUs survey, and the results generally fell into three categories. The first related to the logistics of running nested studies, in terms of the extra resources required, additional complications that might be caused to the delivery of the host trial (such as regulatory delays), and ethical barriers. The second barrier was a lack of perceived equipoise around many proposed recruitment processes and lack of enthusiasm in subjecting them to formal testing. The third category related to scientific issues, including concerns about the power to detect what might be quite small effects from methodological innovations, and the likely impact of variation in the effects of recruitment interventions, in terms of their effects on different sites, in different trials, and at different times.

Limitations of the study

The CTUs survey was limited by the 38% response rate, and it is possible that non-responding units manage recruitment and retention differently from those included in the survey. Workshop participants (academics and staff in CTUs) represent key stakeholders, but the views of those attending a workshop on recruitment and retention may not have been representative of the wider trials community, and the findings would need confirmation in other contexts. Importantly, different priorities may be identified by other stakeholder groups, and in different countries. Particularly, there is a need to replicate these findings with patients and carers as core stakeholders in recruitment and retention. In this study, the CTUs survey was used to develop a list of recruitment interventions to feed into discussions in the workshop, but the content generated by the survey and the priorities generated by the workshop were not formally triangulated in any way.

What are the limits to the impact of recruitment and retention interventions?

As noted previously, a recent review outlined three core areas of relevance to improving recruitment and retention: infrastructure, stakeholder engagement with research, and methodological innovation. In this paper, we have focused on methodological innovation, which we believe has an important part to play in improving recruitment and retention performance, and has the advantage being able to be evaluated and implemented throughout the platform of current clinical trials in a rigorous and controlled manner. Although the results are limited somewhat by the low response rate and the potential for bias, they do give a unique indication of the views of CTUs currently involved in recruitment and retention.

However, it is unclear how much variance in recruitment and retention performance is due to technical issues amenable to methodological research, compared to other issues such as available infrastructure, the organization, leadership, management and culture of research teams, and attitudes and values within the wider community. For example, staff in primary care networks in another workshop identified ‘positive attitudes of primary care staff towards research’ and ‘trust of researchers by potential participants’ as key contextual factors [ 37 ]. These factors are not necessarily those that are the most amenable to empirical testing, especially in a formal randomized comparison, although there are relevant examples [ 38 ].

It is noteworthy that many of the issues felt by our respondents to be worthy of evaluation are likely to have relatively modest effects on recruitment or retention, although this may reflect the fact that suggestions for interventions of higher impact (such as incentives) may be viewed as of low feasibility because of regulatory and ethical barriers. The scientific benefits of modest impacts on recruitment may be small (an increase in recruitment rates from 10 to 15% may have little substantive effect on external validity), although the benefits in terms of logistics, time taken to recruit, and trial funding may still be significant, given that the recruitment period may be a key driver of the length of a trial and its overall cost. Smaller benefits may be more important in retention.

It is possible that issues of efficiency are equally important. For example, rather than adopting methods with the aim of increasing the proportion of eligible patients who participate, studies may focus on whether more efficient methods can be adopted to maximize the number of patients who can be approached (although this is of course less relevant in certain contexts, such as rarer diseases). For example, in primary care, many trials have adopted postal recruitment using existing disease registers in preference to traditional recruitment led by clinicians [ 39 ]. The proportion of patients recruited by such postal methods may be equal to or less than traditional methods, but allows recruitment over a wider geographical area whilst using the same resources.

A research agenda for recruitment and retention interventions

The results of this survey and workshop raise a number of implications for a future research agenda in this area. Experienced trial staff may have implicit ideas about what works in recruitment and retention, and a wide variety of factors are thought to be relevant. Some of these are likely to reflect good research practice and may not need or warrant empirical testing. However, given the importance of recruitment and the disruption it can cause, there is a surprisingly limited consensus on what needs to be tested to make recruitment practices more evidence-based. Authors of systematic reviews have commented that interventions that do get tested often bear an uncertain relationship to those in the broader literature, making pooled analyses difficult. We have highlighted three core areas that were felt to be a suitable focus for future work, and have considered some of the issues that might be amenable to testing. Further advances in this area may well be facilitated by the development and adoption of frameworks and typologies of recruitment methods of the type that have been adopted in other areas exploring complex, behavioral interventions [ 40 ]. This would involve describing categories of interventions and their potential mechanisms of effect, as well as potential moderating factors, such as the impact of different patient and trial characteristics. As well as providing benefits in terms of the development of effective interventions, this would allow more effective pooling of analyses at the synthesis stage.

Experienced trials personnel such as those involved in the surveys and workshops may be used to dealing with a lack of equipoise among clinical staff [ 41 ]. Therefore, it is noteworthy that there is not always equipoise among such staff about the effects of recruitment interventions, which can potentially act as a barrier to their evaluation. This raises the issue of how the delivery of nested recruitment interventions can be better incentivized. For example, individual trial teams and CTUs might receive additional resources to support their attempts to nest recruitment and retention studies in their trials to increase the adoption of this approach.

Scientific objections to evaluations of recruitment and retention interventions around issues such as power and heterogeneity are reasonable, although effective categorization, pooling, and meta-analysis could allow for the testing and consideration of many of these issues. The Medical Research Council Systematic Techniques for Assisting Recruitment to Trials (MRC START) program [ 42 ] and related initiatives such as Studies Within A Trial (SWAT) [ 43 ] and TrialsForge [ 44 ] may encourage a common framework across recruitment interventions and pooling to provide a more precise estimate of their effects, and to explore variation in their effects across patient populations, trial types, and recruitment contexts.

Significant resources continue to be invested into clinical trials, but recruitment and retention continue to be problematic and remain high priorities among CTUs in the United Kingdom. There continues to be a major gap in the evidence base regarding what works in recruitment and retention. These findings provide guidance on areas that may be prioritized in the funding of further methodological research in this important area.

Abbreviations

95% confidence interval

Clinical Trials Unit

Odds ratio, RR: risk ratio.

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Acknowledgements

The workshop was funded by a research project grant from the MRC Network of Hubs for Trials Methodology, R24. The survey was funded by the MRC North West Hub for Trials Methodology Research. The funders had no role in the design, collection, analysis, and interpretation of data; in the writing of the manuscript; and in the decision to submit the manuscript for publication.

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Peter Bower

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Valerie Brueton

North West Hub for Trials Methodology Research, University of Liverpool, 1st floor Duncan Building, Daulby Street, Liverpool, L69 3GA, UK

Carrol Gamble

Health Services Research Unit, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK

Shaun Treweek

North West Hub for Trials Methodology Research and Department of Biostatistics, University of Liverpool, 1st floor Duncan Building, Daulby Street, Liverpool, L69 3GA, UK

Catrin Tudur Smith & Paula Williamson

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Authors’ contributions

PW and CTS conducted the CTU survey. PW conceived the idea for the workshop. PB, VB, CG, ST, CTS, BY, and PW contributed to the workshop. PB drafted the manuscript, with additional sections written by ST, VB, and CTS. PB, VB, CG, ST, CTS, BY, and PW gave final approval for the version to be published, and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All authors read and approved the final manuscript.

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Bower, P., Brueton, V., Gamble, C. et al. Interventions to improve recruitment and retention in clinical trials: a survey and workshop to assess current practice and future priorities. Trials 15 , 399 (2014). https://doi.org/10.1186/1745-6215-15-399

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DOI : https://doi.org/10.1186/1745-6215-15-399

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Factors influencing recruitment to research: qualitative study of the experiences and perceptions of research teams

Lisa newington.

1 NIHR Biomedical Research Centre, Guy’s and St Thomas’ NHS Foundation Trust and King’s College London, Guy’s Hospital, SE1 9RT, London, UK

Alison Metcalfe

2 Florence Nightingale School of Nursing and Midwifery, King’s College London, James Clark Maxwell Building, SE1 8WA London, UK

Recruiting the required number of participants is vital to the success of clinical research and yet many studies fail to achieve their expected recruitment rate. Increasing research participation is a key agenda within the NHS and elsewhere, but the optimal methods of improving recruitment to clinical research remain elusive. The aim of this study was to identify the factors that researchers perceive as influential in the recruitment of participants to clinically focused research.

Semi-structured interviews were conducted with 11 individuals from three clinical research teams based in London. Sampling was a combination of convenience and purposive. The interviews were audio recorded, transcribed verbatim and analysed using the framework method to identify key themes.

Four themes were identified as influential to recruitment: infrastructure, nature of the research, recruiter characteristics and participant characteristics. The main reason individuals participate in clinical research was believed to be altruism, while logistical issues were considered important for those who declined. Suggestions to improve recruitment included reducing participant burden, providing support for individuals who do not speak English, and forming collaborations with primary care to improve the identification of, and access to, potentially eligible participants.

Conclusions

Recruiting the target number of research participants was perceived as difficult, especially for clinical trials. New and diverse strategies to ensure that all potentially eligible patients are invited to participate may be beneficial and require further exploration in different settings. Establishing integrated clinical and academic teams with shared responsibilities for recruitment may also facilitate this process. Language barriers and long journey times were considered negative influences to recruitment; although more prominent, these issues are not unique to London and are likely to be important influences in other locations.

Participant recruitment is vital to the success of a research study, and yet many research projects fail to recruit a sufficient number of participants [ 1 ]. Increasing participation in clinical research has become a key area of focus within the NHS, with the aim of facilitating evidence-based policy, improving health outcomes and reducing health inequality [ 2 ]. The identification of optimal recruitment methods is gaining interest and a recent systematic review of strategies aimed at improving recruitment to randomised controlled trials (RCTs) identified 45 relevant studies and categorised six types of intervention: trial design, obtaining consent, approach to participants, financial incentives, training for recruiters and trial coordination [ 3 ]. Overall, the general strategies found to be effective in improving recruitment included: making telephone reminders to non-responders, having opt-out procedures where potential participants are required to contact the trial team if they do not want to be contacted about a trial, and having open rather than blinded trial designs [ 3 ]. It is not known whether more trialists are now adopting these strategies, or if they are proving successful in other settings or for other research methodologies.

Attempts to optimise recruitment and retention for non-interventional research studies include a range of techniques, such as using large sampling frames, sending reminders, running wide-scale publicity campaigns, providing free helplines and providing material in the respondents’ own languages [ 4 ]. While there may be universal elements to improving clinical research recruitment, reports of successful recruitment strategies for non-intervention studies are often directed at the particular target demographic group, for example: African American Elders [ 5 ], palliative care patients and their carers [ 6 ], adolescent mothers [ 7 ] and individuals from minority groups [ 8 ]. It is clear that recruitment and retention strategies need to be relevant to the target population and the research methodology used, and therefore the optimum strategy is likely to vary. However, further investigation of research recruitment according to different study designs is required to enable an evidence-based approach to recruitment.

The views of the researchers and clinicians involved in participant recruitment are beginning to be explored. We recently conducted a systematic review and thematic meta-synthesis to investigate this subject and found that the recruitment process could be defined by five key themes: building a research community, securing resources, the nature of the research, professional identities, and recruitment strategies [ 9 ]. Across all five themes there were reports of competition and compromise. Competition arose over funding, staffing and participants, and between clinical and research responsibilities; whilst compromise was needed to create study designs that were acceptable to patients, clinicians and researchers. Overall the views of researchers and clinicians were similar, which was partly explained by the overlapping elements of their roles.

The factors and situations that prompt some individuals to agree to participate in clinical research when others decline have also received attention, with the hope of informing new recruitment practices. However, to date, this work has been predominantly directed at a single medical condition and there have been varied findings [ 10 - 14 ].

Geographical location has been shown to influence recruitment rates to RCTs, with large cities such as London associated with poorer recruitment [ 15 , 16 ]. Possible suggestions for lower recruitment rates in London are the more varied ethnic population (individuals who are traditionally more difficult to engage in medical research), higher population mobility (individuals potentially missing invitations or reminders to participate), and more university hospitals (creating research fatigue as individuals are repeatedly approached to participate in research) [ 15 ]. Research teams in London therefore not only have to contend with the recruitment issues faced elsewhere, but may face an additional set of issues associated with their location.

The aim of the current study was to identify and understand the factors affecting recruitment to clinically focused research in London, UK, with the aim of mapping the existing strategies and informing new approaches. This study adds to existing work by exploring pertinent themes that arose across different clinical areas, study designs and researcher roles, providing a broad view of the factors that researchers consider important for the recruitment of clinical research participants. The following questions were explored:

1) What do researchers perceive to be the influential factors in recruiting participants to their clinically focused research?

2) What steps do research teams take to optimise recruitment to their studies?

3) What are researchers’ perceptions of why potential participants consent or decline to participate in their research?

4) Does being located in London create any additional issues with recruitment?

A convenience sample of three research leads involved in clinically focused research and based in teaching hospitals in South London were identified and invited to participate in a one-off interview to discuss their experiences and perceptions of recruiting participants for their studies. The phrase clinically focused research was defined as any medical research requiring an individual’s consent to participate, including donation of tissue samples, observational studies and RCTs, and the discussion was limited to recruiting adult patients able to give informed consent. The interviews were semi-structured and used non-directive, open-ended questions based on topics identified from preliminary discussions with clinical researchers and from the existing literature; the topic guide is listed in Table  1 . Each participant was asked to identify other members of their team with differing roles and responsibilities, and a purposive sample of these individuals was also invited to participate in the study. The same topic guide was used throughout and additional individuals were identified as necessary to ensure a broad mix of research professions were included, and to enable interviewing to continue until saturation was reached. All interviews were conducted face-to-face by the primary author in early 2013 at locations chosen by the participants. The interviews were audio recorded and transcribed verbatim.

Interview topic guide

The interview data was analysed using the framework method established by Ritchie and Spencer [ 17 ]. The framework matrix was developed using NVivo 10 software (QSR) and incorporated the interview topic guide, ideas from the existing literature and prominent themes identified from a preliminary review of the transcripts. The transcripts were coded line by line and additional themes were entered into the matrix where necessary. The matrix was populated with summarised data according to participant and theme, and used to identify common and divergent issues in answer to the study research questions.

Ethical approval

This study was approved by the King’s College London, College Research Ethics Committee (Reference PNM/12/13-106). All participants gave informed consent to be interviewed. All but one participant also consented to anonymous quotes from their interviews being used in the resulting reports and publications.

A total of 15 individuals were invited to participate in the study, of which 11 agreed to be interviewed. Participant demographics are shown in Table  2 . One speciality registrar declined to be interviewed, citing that his role was predominantly clinical not research-based, and three speciality registrars did not reply to their invitations. The mean interview duration was 28 minutes, ranging from 19 to 48 minutes.

Participant demographics

*Medical doctor receiving advanced training in a specialist area.

The information provided has been limited to preserve the anonymity of the interviewees and their teams.

Interviewees were involved in a range of studies, all outpatient-based and run as part of three research teams (A, B and C) in three tertiary care hospital sites in South London. Study designs included a first-in-man drug trial, longitudinal observational studies, laboratory studies requiring one-off anonymous tissue samples, genetics studies, trials of therapy interventions, and physiological studies. All research teams carried out research with patients and healthy volunteers, and most interviewees had volunteered themselves as study participants at some stage. With the exception of the two clinical research scientists and the clinical research associate, all participants were also involved in clinical activities as part of their role. When asked why they became involved in clinical research, all participants reported having an interest in research at an earlier point in their career and acting upon this for a variety of reasons including: an extension of a previous role, the desire for more control over their work, part of their current training, to learn more about evidence-based medicine, to do something worthwhile, to improve job satisfaction and to ensure more sociable working hours. All interviewees were educated to degree level, four had gained a PhD and two were working towards a PhD or MD. All participants acknowledged difficultly in recruiting research participants and mentioned particular strategies or modifications that were made to improve recruitment within their teams. The general perception of recruitment was that it is hard to recruit the desired numbers in the allocated time and that more often than not, extensions to the recruitment period are required.

Influential factors in the recruitment of participants

Numerous factors were identified by the interviewees as influential in the recruitment of research participants and these were categorised into four main themes: infrastructure, nature of the research, recruiter characteristics and participant characteristics.

Infrastructure

The need for access to potentially eligible participants was emphasised throughout. Collaboration between hospital clinicians, GPs and researchers were viewed as essential for the identification of eligible patients and to avoid clinician gatekeeping. All research teams had established systems to facilitate the identification of patients, but there was awareness that potentially eligible patients seen in other departments or hospitals were frequently inaccessible.

“There will be a lot of patients going to [smaller hospitals], who could be enrolled in studies, but they’re not available there. They are available here. If they knew that we were doing it, and there was a mechanism for moving those patients for the duration of the trial here, I would think everyone would be happy. But there isn’t” . (Consultant, team A)

One team had developed a strategy where local hospitals were encouraged to identify eligible patients and refer them to the participating site for the duration of the trial. Whilst this was seen as a positive step, it was also acknowledged that greater recognition for the referring sites, in terms of funding and co-authorship, would be required to improve uptake.

The preparatory work carried out by research teams was considered highly influential in the success of recruitment. Screening patient records, identifying eligible patients, preparing appropriate recruitment material and ensuring that the relevant clinicians and researchers were fully informed about the study, were all recommended. These tasks were primarily the responsibility of the research nurses and research associates.

“Here, we do look through the clinic list and, myself on the busiest days, will look at the past three clinic letters and see if they’re going to be suitable, or if they’re already on the study. We do recommend that’s the best way to find patients. And then we’d print the relevant paperwork and put that in the notes, so the doctors can see. So then they don’t even have to think about it, it’s just there. I think that works best. I would say that maybe about half of places do that, because they haven’t got time. They haven’t got time to do the prep” . (Clinical research associate, team A)

One suggestion to improve access to patients was the use of opt-out systems. This was mentioned with reference to patients being required to opt out of research teams contacting them about relevant research projects, but was also discussed with regard to opting in to the routine donation of anonymous tissue samples (surplus to requirements for clinical tests) for clinically focused research. Neither system was currently in place.

Issue with the regulations surrounding ethical approval and the content of participant information sheets were commonly discussed. The interviewees thought that the approval process was too slow, which created delays in starting recruitment and raised concerns that their departments would get overlooked for involvement in multi-centre studies in favour of sites with faster turnaround times.

“We certainly need to improve the speed with which we’re able to take a study from application through to actually being run. We are unbelievable slow. Unbelievable top heavy with regulation… It often means, locally, that we get bypassed in these programmes” . (Consultant, team A)

The interviewees were also concerned that the information required by ethics committees led to the participant information sheets becoming excessively long and detailed, and off-putting to patients. The researchers were aware of the conflict between ensuring patients had sufficient information about a study to make an informed decision about participation, and providing accessible study literature, however many interviewees believed that with the current format, patients did not actually read the information sheets provided, instead relying on verbal discussions to make a decision about participation.

“I get a few who will [read the patient information sheets], but nobody does. I would say 98% of people don’t read it. I do a summary of what is important to them” . (Specialty registrar, team C)

Several researchers suggested inviting patients and members of the public to sit on ethics committees to provide feedback on this issue and one research team had implemented a strategy to use more images and pictures in their participant information sheets to improve readability.

Increasing public awareness of clinically focused research was widely thought to have the potential to improve research recruitment, with the exception of one interviewee who felt that people would only be interested in research when their health was affected. Whilst there were many comments on the need to increase awareness of research within hospitals and other healthcare facilities, interviewees had few suggestions of how this could be improved. There was frustration at the lack of media coverage or celebrity endorsement within their clinical areas, compared to the numerous high-profile campaigns for areas such as cancer research. However, the media was viewed as having both positive and negative effects on recruitment, depending on the nature of the coverage.

Nature of the research

The influence of the type of research on participant recruitment was discussed by all interviewees. It was noted that clinical trials were harder to recruit for than observational studies because they require greater commitment from the participants in terms of time and risk. The interviewees also acknowledged the difficulty between designing studies that were appealing to potential participants and ensuring they were scientifically robust.

“We wanted it to be a good trial from the beginning. So it wasn’t just ‘everybody gets [the intervention] and let’s see what happens’. Although that would have been much easier and might have given us the answer quicker. So it’s placebo controlled, randomised, double blind. Not only are we asking these people to possibly risk their lives, but they might not get it anyway” . (Clinical research scientist, team B)

Some studies incorporated open label or crossover phases after the initial RCT, which was believed to make the study more acceptable to patients. Other recommendations, such as allowing patients to have their study blood tests carried out in the community and offering evening and weekend research appointments, were suggested to reduce the time burden of research participation, but these strategies had not been adopted.

“I guess the big thing would be to try and reduce the burden of commitment to patients, as much as possible. If there was any chance that they could have research bloods taken with GPs, or in their local community, or research nurses could go and take the blood in their home, to avoid this” . (Research nurse, team A)

Payment for research participation was also discussed. Research leads highlighted the ethical issues associated with paying patients for research participation, whilst others acknowledged the role of payment as a driver in recruiting people to participate in their work. The semantics of this issue were important, with one interviewee stating that while it was unethical to pay patients to participate in research, there was the need to explore “being able to financially help volunteers better” . (Consultant, team A).

Recruiter characteristics

It was widely reported that patients were more likely to agree to participate research if they were asked by a medical doctor, specifically their usual doctor. Even for observational studies, which do not require a doctor to take consent, it was noted that recruitment was more successful if the doctor mentioned the study to the patient before the research nurse provided a more detailed explanation. In this respect, successful recruitment was seen as a team effort.

“Our clinicians are so pro-research they are very good at introducing it into the clinical consultation, which really helps, because if it’s first mentioned, I think, by a clinician it’s considered just a normal part of the clinical care, then I think people are sometimes a bit more accepting of it” . (Research nurse, team A)

In addition to the recruiters’ professional roles, their personality and knowledge of the research project were also considered influential. Although all interviewees had undergone the relevant research and ethics training, none had received specific training in recruitment. There was debate on whether it was possible to teach the art of recruitment and if so whether this would be useful. The more experienced researchers felt that specific training was unnecessary as recruitment style and strategy vary depending on the clinical speciality and the particular study involved, and on-the-job experience was believed to be more important that generic recruitment training. It was also suggested that an individual’s personality was central to their recruitment success, an aspect that is difficult to teach.

“ The art of getting people in; it’s not clear. If I couldn’t recruit to trials, I wouldn’t be doing trials… some of my colleagues are good at recruiting, some aren’t quite so good. Trying to tell someone what to do is just not helpful, is it? ” (Consultant, team B)

“Then it’s also your personality. I think patients, they need to trust you. If you are a little bit unsure about something – not about the protocol itself, because that changes and you can’t expect to know a thousand pages of protocol – but that you are confident. Holding their hands all they way during the study” . (Research nurse, team B)

The less experienced researchers believed they would have benefited from additional support during the early stages to learn how to optimise their recruitment success, but acknowledged that a general training programme was unlikely to be appropriate for all recruitment situations.

Interviewer: “Did anyone talk to you about recruiting?”

Respondent: “No, but it would have been helpful… No-one spoke to me and gave me any advice… Although studies are so different and patient groups are so different, that it’s probably slightly different for everyone” . (Specialty registrar, team A)

The clinical research scientists expressed frustration at being reliant on clinicians to recruit patients for their research, especially as they had completed the prerequisite training and had recruited patients previously; however current regulations prohibit non-clinicians from recruiting patients.

“I don’t know why they don’t think [scientists] can consent people here. We used to be able to. It’s only the last few years that we’ve not been able to. We’ve done all the consent courses and everything” . (Clinical research scientist, team B)

Participant characteristics

All interviewees thought that certain patients were more likely to agree to participate in clinically focused research than others. The reported reasons for this are explored in more detail in the section “Why do some individuals consent to participate and others decline?”, however it is important to highlight that for a potential participant to either consent or decline to participate in research, they must first be invited. This links to the previous issues of identifying and accessing eligible patients, but also relates to situations where potentially eligible patients may be denied the opportunity to take part. For example, several interviewees mentioned that individuals who do not speak or understand English are unable to participate in the majority of studies due to the absence of funding for interpreter and translation services.

“…that’s actually something we really need to think of as a team going forward with recruitment, because at the moment we’ve said, for example, if patients come with interpreters or they have no English, then we haven’t included them” . (Research nurse, team A)

One interviewee recalled using interpretation services in the past, but only as a last resort due to the additional workload created.

“It did happen in the past, that for some protocol it had been waived that you can have an interpreter, which can’t be a relative. Because it needs to be an independent interpreter. It needs to be really last chance, because it’s a lot of work, extra, on top of what you have to do” . (Research nurse, team B)

Where potential participants did speak sufficient English to be eligible for participation, but it was not their first language, some interviewees reported lower recruitment rates compared with native English speakers. Suggested reasons for this included communication issues or a general increased reluctance to participate in clinical research.

“Potentially there have been times in the past where I’ve felt that this person’s not really taking in what I’m saying, for various reasons, whether that’s to do with language differences, English not as a first language” . (Research nurse, team A)

Steps taken to optimise recruitment

Table  3 shows the recruitment strategies and specific techniques employed by the research teams and the interviewees’ suggestions of techniques to further improve recruitment. The recruitment strategies were divided into three main themes: preparation and planning, engendering patient support, and collaboration with clinicians. The majority of suggestions to improve recruitment were targeted at making research participation more appealing and less time consuming for patients.

Steps taken by research teams to optimise recruitment and interviewees’ suggestions for improvement

Why do some individuals consent to participate and others decline?

The interviewees believed that the main reason why patients agreed to participate in their research was altruism, including the desire to help future patients and the wish to give something back to the hospital and team that cared for them. For the latter, researchers were clear to point out their duty to ensure that research participation was truly voluntary, rather than an obligation.

“A common thing tends to be ‘you’ve done so much for me, I’m quite happy to do anything for you’. Which is a sort of double edged sword actually, because that’s very generous of them, but actually you want them to participate because they want to, and you have to say ‘well you don’t have to’, and you’ve got to think that they’ve actually understood” . (Research nurse, team A)

There was also a general consensus that many individuals who took part in clinically focused research valued the potential benefits of participation, namely the opportunity to access additional health checks, novel treatments, increased contact with clinicians and the clearly defined plan of care. For researchers who provided payment for participation in their studies, financial gain was also viewed as an important motivator.

“Some of the studies that we run here, we pay £50 a visit. So it’s also to do with people need a bit of extra cash at the moment” . (Research nurse, team C)

Furthermore, patients who were interested in the research question and believed that clinical research was worthwhile were considered more likely to accept the invitation to participate. As discussed previously, the nature of the research was also viewed as highly influential, with patients preferring to participate in non-interventional studies.

“I think it’s much easier to recruit for an observational study. Because we’re not doing anything that could harm them” . (Specialty registrar, team A)

No particular strategies were employed to recruit patients of different ethnicities or socio-demographic backgrounds, with the common belief that recruiters attempt to invite all eligible patients to participate, regardless of their background. Despite the fact that recruitment was limited to English language speakers, most researchers felt that they recruited a good spread of the local population, although this did depend on the clinical area under investigation and the time commitment involved.

“I suppose retired patients have probably said ‘yes’ more willingly. For our study, we are requiring them to have extra tests. Some of the patients have said they are worried about time. Or getting here from work earlier” . (Specialty registrar, team A)

For patients who declined to participate in clinical research, the predominant reasons were thought to be practical. Patients who were working were unable to take extra time off work for research appointments and the additional travel required to attend the hospital was also believed to be off-putting, especially for patients who did not live locally.

“I think for some, mainly it’s time I’d say. Because often they’ve been sat in the waiting room for up to an hour already. So when it gets to the point where they’ve had their appointment, they’ve been seen by a nurse… they’re just like ‘I’ve just not got time’. I think that’s the main issue” . (Clinical research associate, team A)

Fear was also considered important, mainly with respect to clinical trials. Fear of taking new drugs, fear of additional diagnoses being discovered from extra screening, fear of needles, fear of symptoms worsening and fear of the storage of tissue or genetic information were all suggested. Language was also thought to play a role. As discussed in the section “Participant characteristics”, some interviewees observed that individuals who spoke English as an additional language were more reluctant to participate compared with native English speakers.

“I have noticed sometimes, I’ve not quantified this yet, because we haven’t analysed out results, but people who maybe don’t have English as a first language are probably a bit more reluctant” . (Speciality registrar, team A)

Specific issues for London

When asked specifically about recruitment issues associated with their location in London, the researchers’ responses fell into two main themes: local research community and patient population.

Local research community

The interviewees described successful research communities within their own teams, although there was a lack of collaboration with local primary care services. It was suggested that establishing shared research databases and other systems to identify and access potentially eligible patients across different service providers would be beneficial for study recruitment, but that specific initiatives would be needed to facilitate this.

“It’s hard because, in my view, if you really want to do it, it will cost money. It will involve someone, a GP with a research interest in the catchment area. For example, they call it GPSI, which is a GP with a specialist interest in something, rheumatology or haematology et cetera, but one would have research, just purely doing research” . (Specialty registrar, team C)

In addition, researchers reported delays in the process of gaining ethical approval for their studies and a lack of financial support for in-house academic research, suggesting that local improvements could be made to these systems.

Despite these recommendations for improvement, the interviewees were generally positive about working in London and the level of research support provided.

“I think in terms of being in a big London teaching hospital, we are more geared up to research, just from personal experience having worked in district generals in [UK county], there was no set up for research and it was very much a minor thing, and if anyone was doing something, they didn’t have research nurses, it was very much clinician led. It was set up in their own interests really, their own studies. So the fact that we have a forum for research nurses here, and we are trying to actively put out the research message” . (Research nurse, team A)

Patient population

It was noted by the researchers that patients attending hospital appointments in London frequently report long travel times and this was believed to be detrimental to recruitment. This was attributed to the broad catchment area for tertiary healthcare, plus the large number of people who commute into London for work. Interviewees reported difficultly recruiting patients with long journey times, especially if research participation involved additional visits.

“There’s quite a large population of people that travel in. I guess that will affect people taking part in research. Because if they’re having to travel from Hertfordshire, that’s going to put people off, because yes, you can give them their travel expenses, but you can’t give them their three hours back” . (Research nurse, team C)

Being a tertiary care centre was also thought to have a positive effect on recruitment, with researchers commenting that patients may be more likely to trust an invitation for research participation from a specialist centre.

“So people do come in from other hospitals. Again, you have a wider group. Also, they tend to be, in a way, more sick. More likely to listen to the medic who’s telling them, ‘this isn’t a bad thing’” . (Clinical research scientist, team C)

The interviewees also discussed the diversity of the local population, and as mentioned previously, the lack of interpretation and translation services for research resulting in potentially eligible patients being excluded. However, in general it was felt that the researchers were able to recruit representative samples of their local populations.

Although all these issues were important to researchers, it was also acknowledged that most locations have problems with recruitment and that having sufficient resources and research staff should perhaps be considered more important than the location.

“I wouldn’t say there are any huge differences that I can think of. I think it really does depend on the staff and the resources that they’ve got, rather than the actual hospital and the patients coming in” . (Clinical research associate, team A)

The primary aim of this study was to identify the factors that researchers perceive as influential in the recruitment of participants to their clinically focused research. Infrastructure, the nature of the research, recruiter characteristics and participant characteristics were all deemed important. The first three themes are, in theory, more amenable to modification than the last, for example through the development of systems to improve identification and access to eligible participants [ 18 ], designing studies with reduced participant burden [ 10 ] and ensuring that recruiters have the appropriate knowledge and skills [ 19 ]. The discussion of participant characteristics focused on the concept that certain patients were thought more likely to agree to research participation than others. The danger with such an observation is the potential for recruiters to stereotype potential participants based on previous experiences, and therefore choose not to approach individuals who are otherwise eligible. As the NHS constitution pledges to inform all patients of research studies that are relevant to them and in which they may be eligible to participate [ 20 ], recruiters must be aware of the potential to deviate from this duty. In reality, the decision to participate in clinically focused research is frequently multifaceted and requires potential participants to consider the personal pros and cons of taking part at any given time [ 13 ]. The research nurses interviewed for the current study raised this point and explained their attempts to approach all eligible patients, regardless of any preconceptions about whether or not they would agree to participate.

The general perception that doctors are more successful at recruiting research participants than nurses has been explored previously. Donovan et al. [ 21 ] found no significant difference in recruitment rates between urology consultants and nurses for a prostate cancer RCT and calculated that nurses were more cost-effective recruiters, despite spending longer on average with each patient. In the current study, recruitment was viewed more as a team effort. Having the doctor mention research participation as part of the routine consultation was thought to be beneficial, as was having integrated clinical and academic teams on site. However, these strategies require sufficient staffing and resources and rely on specific funding for research posts [ 9 ]. The possible recruitment benefits of having an established therapeutic relationship with potential study participants [ 22 ], sharing similar cultural backgrounds or languages [ 23 ], and employing peer recruiters [ 24 , 25 ] have all been explored in the literature. However, the influence of the recruiter-participant relationship was not widely discussed by the interviewees, nor were the subjects of culture and ethnicity. There was a general consensus that recruiters adopted the same recruitment strategies for all demographic groups, but observational investigations of recruitment practices would be beneficial to further explore these issues. The use of eligibility criteria that include only those who speak sufficient English was attributed to a lack of resources available for interpreter services. Resource limitations would also restrict the use of peer recruitment programmes or other strategies aimed at including minority groups. As recruiting a representative sample is essential for the generalisability of research findings [ 26 ], additional investigation of this issue is required.

The research scientists interviewed were disappointed that they were no longer permitted to discuss their study directly with potential participants. This finding echoes the views of biomedical research scientists involved in placental perfusion studies [ 27 ]. The scientists raised legitimate concerns that the individuals involved in recruitment did not have sufficient knowledge of the intricacies of the study to be able to fully explain the background and rationale to potential participants, or to answer questions about particular methodologies [ 19 ]. It in current study, it was local, rather than national, policy that dictated the exclusion of research scientists from recruitment activities. The potential benefits of allowing research scientists to recruit participants to their research include reducing the workload for clinicians, providing expert knowledge of the study processes and rationale, and separating research recruitment from routine clinical care. The potential drawbacks include the research scientist having a vested interest in the research without the balance of coexisting clinical duties, and the absence of a previous therapeutic relationship with the patient. Further exploration of this issue is required, however it may be advantageous to consider including clinical research scientists as part of the recruitment team, with safeguards to guarantee that patients are not exploited.

The recommendation to use an opt-out system, where patients are required to contact the research team if they do not wish to be invited to participate in clinical research, was made in a recent systematic review [ 3 ]. Several interviewees suggested that this might be a beneficial system, however this strategy is not currently employed, and further work is required to pilot the use of opt-out within these settings. A variation of this strategy, where patients are invited to opt-in to the anonymous donation of surplus tissue after clinical tests, was also discussed. This type of tissue biobanking is available at the interviewees’ hospital sites for patients with a diagnosis of cancer, but is not routinely adopted in other clinical areas. Further research into the extension of biobanks to include other clinical specialties appears warranted [ 28 ].

The use of open, rather than blinded trial designs, and telephone reminders were also recommended by Treweek et al. [ 3 ]. There is debate over the utility of open study designs due to the potential for increased bias [ 29 ], but this methodology is gaining support [ 30 ]. The interviewees used modified versions of this strategy, such as having an open or crossover phase after the main trial, and believed this was beneficial for recruitment. None of the interviewees specifically discussed the use of telephone reminders.

The recruitment strategies employed by the interviewees were similar to those identified in our recent meta-synthesis, although there was less focus on emphasising the benefits of research participation in the current study [ 9 ]. In addition to the possible coercive aspect of emphasising the benefits , the interviewees believed that altruism was the key reason for patients accepting the invitation to participate, and therefore strategies based on highlighting potential personal benefits would not sit with this premise. The dominance of practical issues as proposed reasons for patients declining the invitation to participate in research have been documented elsewhere [ 9 , 10 ].

The key factors associated with conducting clinically focused research in London were language and travel time. Interviewees were unable to offer interpretation services to facilitate discussions about research with patients who did not speak sufficient English. The most recent government data shows that within the associated South London boroughs between 19.6-20.3 % of residents do not speak English as their primary language, compared with 15.3 % and 7.1 % in the next biggest UK cities Birmingham and Leeds, respectively [ 31 ]. The range of primary languages spoken is also greater in the interviewees’ regions, with more than 54 different languages, compared to 36 in Birmingham and 29 in Leeds [ 31 ]. Traditionally, individuals from ethnic minorities have been considered less likely to participate in clinically focused research, however studies from the USA suggest that this is not the case and recommend that more needs to be done to ensure access to research for minority groups, rather than interventions aimed at increasing willingness [ 32 - 34 ]. Strategies to aid the removal of language barriers identified in the current study would improve access to research and could potentially increase recruitment, however further investigation is required.

The interviewees also observed that patients with long travel times to the hospital were less willing to take part in research. When designing clinically focused studies, it may therefore be useful to explore the interviewees’ suggestions of increasing the use of information technology for data collection and forming collaborations with local healthcare services to minimise participant travel. As the average commuting time is 48 % longer in London than elsewhere in the country [ 35 ] this factor may be less problematic in other locations, however most tertiary and quaternary healthcare services conducting research are likely to experience similar travel issues.

Strengths and limitations

The current study adds to previous work by providing experiential reports and perceptions from research teams in three different non-cancer outpatient settings, within a specified geographical location. However, as the research teams involved were based in South London, further work is required to ascertain whether these findings translate to other regions, nationally and internationally.

Although interviewing was continued until saturation, the small sample size in the current study means it is not possible to infer any differences between the experiences and opinions of the different professions within the research teams. Furthermore, the current study relied on information collected from semi-structured interviews, and may have been subject to reporter bias. Attempts were made to minimise the degree of bias by selecting independent research teams and interviewing participants individually. Additional explorations of the researchers’ practices that include observation of the recruitment situation would be beneficial, but were beyond the scope of the current study.

Infrastructure, nature of the research, recruiter characteristics and participant characteristics were all believed to influence the success of recruitment to clinically focused research. Suggestions to improve recruitment included reducing participant burden, providing support for individuals who do not speak English and forming collaborations with primary care to improve identification of, and access to, potentially eligible patients. Despite the focus on London in the current study, the factors identified are not unique to this location and are therefore likely to be representative of other diverse cities within the UK.

Competing interests

There were no competing interests in the conduct of this study.

Authors’ contributions

LN and AM made substantial contributions to the design of the study. LN carried out the interviews, conducted the analysis and wrote the final manuscript. AM advised on research conduct from inception to completion, appraised the analysis process and revised the manuscript. Both authors read and approved the final manuscript.

Pre-publication history

The pre-publication history for this paper can be accessed here:

http://www.biomedcentral.com/1471-2288/14/10/prepub

Acknowledgements

The authors would like to thank and acknowledge the contribution of the researchers who gave their time to be interviewed for this study.

This research was supported by the National Institute for Health Research (NIHR) Biomedical Research Centre at Guy’s and St Thomas’ NHS Foundation Trust and King’s College London. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.

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