A Primer on the Importance of Recruitment and Retention in Clinical Trials

Clinical Researcher—April 2023 (Volume 37, Issue 2)


Tiffany Ashton, MAS


It is not a surprise that clinical research professionals who are involved with patient recruitment for a clinical trial widely consider enrollment to be one of their most challenging and stressful job responsibilities. Just read these statistics:

  • 19% of clinical trials were closed or terminated due to failure to recruit enough participants, which is detailed in the study discussed here.
  • More than half of ongoing clinical trials struggle with patient recruitment. Depending on the type of trial, this number can climb up to 85%, as mentioned in this article on the National Institutes of Health (NIH) website.
  • According to Atlant Clinical, 15% to 40% of enrolled participants drop out of their trial prior to completion.

Study recruitment and retention are very important parts of each study because a study cannot move forward without participants. However, depending on the study, it can be extremely difficult to find enough willing and eligible participants. In addition, since patients can choose to withdraw consent at any time, retention efforts are integral for a study to continue.

What is Patient Recruitment?

Patient recruitment is when sponsors, contract research organizations (CROs), study sites, or recruitment companies use strategies to try to connect with patients who may be eligible for their clinical trials. These recruitment strategies are usually based on methods that have been successful in previous studies.

Recruitment is a long process that generally takes more time than any other step of the trial. It begins with research about the patient population and the creation of a plan for outreach. It continues by connecting with potential participants, determining if they are interested and eligible, and moving forward with the consent process.

This article from Advarra offers helpful visuals and information about patient recruitment and enrollment.

Why Patient Recruitment is Crucial to the Success of a Clinical Study

There are many reasons someone may choose to participate in a clinical trial. Some patients believe they may receive better treatment or that their results may help others. While both may be true, enrollment continues to be a struggle in the majority of research studies.

When the initial recruitment strategies do not produce their intended results, the study team is responsible for brainstorming new ideas to boost recruitment.

Recruitment delays cause increased stress for study team members due to the pressure they often receive from the sponsor to advance recruitment and make up for lost time. The sponsor is at risk of losing a lot of money due to delays, and its priority is to fund a successful clinical trial.

When recruitment is delayed, the trial can be affected in the following ways:

  • Budget overspend
  • Extended timelines
  • Inability to properly analyze the investigational drug or device

Negative impacts caused by recruitment delays may lead to the failure of the clinical trial. This is why patient recruitment is crucial to the success of a clinical trial—and why it is at the forefront of the responsibilities for multiple individuals on a research team.

What is Patient Retention?

Patient retention is defined here by the NIH as “the strategy and tactics designed to keep participants [who are] enrolled in clinical trials from discontinuing participation and dropping out.” The NIH says these three things are needed for a successful patient retention strategy:

  • Treating participants with respect
  • Being considerate of the participants’ time
  • Quickly identifying and overcoming retention challenges

On a clinical trial, patient retention begins when a trial’s enrollment numbers are met. The next goal for a study team is to ensure the highest number of patients complete the study by keeping them actively involved (and retained) through regular communication and check-ins.

It is important for various members of the research team, but most importantly the clinical trial manager and clinical research associate (CRA), both working on behalf of the sponsor, to closely monitor retention rates and initiate risk mitigation strategies if/when retention rates decline.

Risk mitigation strategies are generally discussed early in the study initiation phase of a clinical trial as study team members have a general idea of the retention challenges they may face. However, they must be amenable to adjusting along the way for new, unexpected challenges.

Why Patient Retention is Critical for Each Clinical Research Trial

Patients have the right to withdraw their consent from, or drop out of, a clinical trial at any time. Patients should never be coerced to stay in a trial.

Instead, it is important for research site staff to carry out patient retention strategies in their daily work and communicate concerns and challenges to the CRA.

When too many patients drop out of a trial, the trial is at risk of being “underpowered.” An underpowered study does not enroll enough participants as indicated in the protocol in order to draw a quality conclusion.

According to the NIH, underpowered trials are an issue because in order to keep the trial going, the sponsor may have to expand the number of sites, increase budget allocations, and/or eliminate certain tests from the protocol.

Similar to recruitment delays, patient retention issues and underpowered trials may lead to budget excesses, delayed timelines, and reduced quality of results.

Low patient retention rates can cause a clinical trial to fail. This is why it is important for study teams to make patient retention a priority throughout a study.

The Role Clinical Trial Managers Play with Study Recruitment and Retention

Recruitment and retention are two of a clinical trial manager’s main job responsibilities during the study conduct stage. These managers deal with many challenges throughout a clinical trial, and study recruitment is widely considered to be among the most taxing parts of the role.

A clinical trial manager helps drive recruitment and retention strategies and troubleshoots when initial targets are not achieved. He or she needs to be proactive, regularly track the numbers, and work to identify new recruitment and retention strategies to help the study stay on target.

Clinical trial managers can develop a subject recruitment and retention plan (SRRP) for site staff to complete and revise as necessary throughout the trial. Through the SRRP, site-based recruiters and managers can outline:

  • Recruitment projections each month
  • From where they intend to recruit patients
  • Anticipated barriers and recruitment strategies
  • Site-specific retention strategies

The SRRP allows both the site staff and the clinical trial manager to track progress in real time and make swift changes if needed.

Even though recruitment and retention are extremely important for the clinical trial manager role, these functions are not often part of the training received when someone is promoted to the role or takes it on at a new company. Lack of training and understanding of recruitment and retention can make these job responsibilities even more challenging. That’s why they should be discussed in detail in training courses for aspiring and current clinical trial managers that cover key strategies used to manage clinical trials from study initiation to study conduct to study close-out.

Strategies for Patient Recruitment and Retention

We are going to leave you with some tried-and-true recruitment and retention strategies for saving time, boosting recruitment, and managing retention:

  • Clinical trial managers should ensure that patient compensation is in line with industry standards and Fair Market Value.
  • CRAs should schedule booster visits with sites separate from monitoring visits to discuss in detail any recruitment or retention challenges and create a plan of action.
  • Site staff should check the patient schedule each day and flag potential matches for recruiting studies.
  • Site staff should prioritize positive patient experiences in their recruitment and retention efforts.

Click here to receive a free download that includes more details about the four tips above as well as six additional recruitment and retention tips that can be used to lead your study to success.


The overall goal for a clinical trial is to conclude the study on time, within budget, and with high-quality results. The key is to recruit and consent as many eligible patients to the study as needed to ensure the trial’s enrollment goal is met as quickly as possible. By focusing on the patient and providing a positive patient experience, you are more likely to both recruit and retain participants for your study. Recruitment and retention are a team effort—and when we work together toward a common goal, we are more likely to achieve success.

Tiffany Ashton, MAS, is the Director of Operations and Clinical Trial Manager Course Instructor for ClinEssentials, LLC.