Patient Recruitment in 2023: What Works and What Doesn’t in Clinical Trial Enrollment

Traditional clinical trial systems are burdened with inefficiencies contributing to poor recruitment and retention. Barriers to patient recruitment vary depending on the type of study and indication. Factors that contribute to low participation rates in traditional clinical trials include socioeconomic factors, lack of available clinical trials, not meeting eligibility criteria, proximity to clinical sites, and aspects related to the attitudes of patients and physicians. On factors that affect the attitude of physicians, a recent study on cancer drug development highlighted a lack of awareness of available trials, the complexity of eligibility criteria, site accessibility, resource constraints, and anticipated extra workload.

Patient Perspective in Clinical Trials

Factors that influence the decision to participate in a trial include:

  • lack of awareness of clinical trials
  • distance to clinical sites
  • how the trial is set up and communicated
  • personal circumstances
  • benefits associated with participation.

Neglecting to consider these aspects will impact recruitment. For example, sponsors selecting sites based mainly on site capacity, reputation, and physician expertise can result in the unintended consequence of limiting participation for some patients.

In the pursuit of improving recruitment, several studies have tested the effectiveness of recruitment strategies. The following are ineffective in specific trial settings; however, researchers acknowledge further research, e.g., embedding a parallel-group Study Within A Trial (SWAT) in multiple host trials, is needed:

  • for a study on chronic obstructive pulmonary disease (COPD) management, access to a multimedia information resource alongside patient information materials yielded no benefit for recruitment
  • personalized study invitations were ineffective
  • sending Christmas cards to participants did not improve retention

What Works in Clinical Trial Patient Recruitment

Patient recruitment solutions must consider patient burden, barriers such as site accessibility, and how to reach vulnerable patients with comorbidities and borderline performance status. New approaches have been applied to recruitment and other stages of clinical trials, with some trials being run entirely on technology platforms. To ensure compliance and patient safety, the U.S. Food and Drug Administration (FDA) released guidance for industry, investigators, and other stakeholders conducting trials enabled by digital health technologies.

Patient Engagement. Treweek et al. reviewed studies with strategies to improve recruitment to randomized trials. Only three studies with high-certainty evidence were identified, with the following strategies found to be effective:

  • open trials rather than blinded, placebo trials had an absolute improvement of 10% in recruitment
  • telephone reminders to people not responding to postal invitations had an improvement of 6% (for trials with low underlying recruitment).

Patient-centricity and the involvement of patients in trial design are recognized as critical for trial success. Iersel et al. (2022) introduced a tool based on Maslow’s theory of human motivation to aid in the design of patient-centric trials using patient input. Houghton et al. (2020) identified the following factors that impact patient recruitment:

  • face‐to‐face setting is preferred, with information communicated clearly
  • commitment needed e.g., extra appointments and time involvement is a concern
  • payment was welcomed by some, however, it was not a very important influence
  • influence and opinion of doctor or nurse, family, friends, or the media
  • the chance for improvement, the chance to feel better, or the opportunity to make a difference by helping others influences the decision to participate
  • consideration of each individual instead of “one size fits all”

Decentralized Clinical Trials. DCTs focus on patient-centricity rather than site-centricity, giving patients more flexibility to participate. The application of technology platforms to clinical trials has demonstrated an impact on patient recruitment and retention and has benefits for stakeholders in the clinical trial ecosystem.

Trial Settings. To determine if trial setting impacts patient recruitment, a study compared three trial settings for acute low-back pain, namely a decentralized via telemedicine center arm, a health clinic arm, and a mixed model arm. The study found the decentralized arm to be operationally feasible and well accepted by patients, and to have faster recruitment and improved patient access. The authors acknowledge further investigations in more extensive interventional trials are needed to confirm these findings.

Monitoring and modifying recruitment strategies. A recent study emphasized monitoring and modifying recruitment and retention strategies for ongoing RCTs. For a venous leg ulcer RCT, data monitoring allowed the identification of multiple physical, emotional, and socioeconomic challenges that stand in the way of enrolling in a trial. In response, modifications introduced over time included changes to the inclusion criteria, additional recruitment sites, enhanced communication methods, and addressing patients’ transportation needs.

Patient-centric Market Research and Communications. Academic researchers have found that collecting and analyzing recorded voice responses provide insights into a patient’s expectations and cognitive and emotional state. Patient voices provide researchers with actionable intelligence to improve clinical trial design and enhance recruitment and retention.

Machine Learning. Wu et al. (2022) developed a machine-learning model to predict clinical trial operational efficiency using a novel dataset of over 2,000 clinical trials conducted by Roche over 20 years. Study results demonstrate that operational efficiency can be predicted, and valuable insights can be shared with trial designers to improve patient recruitment.


The Vial CRO is a next-generation tech-enabled CRO that delivers faster and cheaper trials (by more than half) through an end-to-end technology platform. Vial solutions include multi-channel marketing, scalable patient qualification and scheduling, patient database reporting, and a patient referral network to address poor recruitment and retention. In similar applications of technology platforms applied to clinical trials, recruitment was extended across a wider geographical reach, and participation by underrepresented groups increased. For more information on how to partner with Vial, or join a study, visit us here.

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