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September 4, 2020

Common clinical trial patient enrollment challenges

Clinical trials are at the center of the life science industry. To ensure success, clinical trial design requires effective patient enrollment.
common clinical trial enrollment challenges
Updated August 2023

Clinical trials are central to the life science and pharma innovation industries. They are mandatory for new pharmaceutical therapies. They can be highly complex and frequently suffer from site recruitment and engagement challenges and trial designs that do not efficiently match or meet endpoints or goals. They also suffer from patient recruiting, enrollment, and retention challenges that add substantial costs and time to commercialization and patient access.

They are also resource-intensive – the average phase I trial can cost in excess of $4 million, while for phase III the figure is closer to $32 million.

Successful clinical trial design requires effective patient enrollment to justify that investment. (For the purposes of this discussion, we will use the terms clinical trial enrollment and clinical trial recruitment as essentially synonymous.) Let’s explore some of the most common challenges to clinical trial patient enrollment, and how virtual engagement can help overcome them.

Our clients reach their clinical trial patient enrollment goals faster.

The most common clinical trial enrollment challenges

Ongoing COVID-19 impact

Patient safety is paramount during the clinical trial process. It is one of the two core reasons clinical trials exist as required by regulatory bodies, with the second reason being efficacy. The COVID-19 pandemic forced significant delays in clinical trials, but also generated new methods and tools for virtual engagement among all stakeholders, many of which will likely remain in place and in practice given timeline and efficiency gains.

The pandemic also opened new conversations about the benefits of decentralized clinical trials. If non-institutional research sites can work with larger sites with the systems, experience, and supporting volume of patients, the potential to accelerate clinical trials is significant. Virtual or hybrid engagement technologies, including those with proven excellence in KOL engagement, HCP engagement, and KOL mapping, will be foundational must-haves to realize that acceleration potential.

Logistical barriers

According to ClinEdge, patients travel an average of 25.8 miles for clinical trial visits. Finding the right patients for your clinical trial can be a challenge. Sufferers of rare diseases and certain conditions represent a small percentage of the population, and the patients you need may live a long way from your trial site. Certain conditions are also more prevalent in specific geographic areas where patients remain significantly from the nearest trial site. Potential participants can be unwilling or unable to travel or commit to your visit schedule. Such logistical issues remain significant barriers to clinical trial enrollment and patient retention. They can also impact how long clinical trials take.

Virtual life science engagement platforms have matured significantly in the past three to five years, demonstrating positive impact through virtual advisory boards and compliant, user-friendly clinician and patient engagement platforms that reduce the number of site visits required – thereby expanding site and patient enrollment potential.


The FDA has reported that 75% of US trial participants are white. Clinical trial teams are responsible for ensuring appropriate representation at clinical trials. But in the US, racial and ethnic minorities remain chronically underrepresented. Without diverse patient enrollment, it’s impossible to ensure that new drugs, devices, and procedures will work consistently across various populations. However, language, cultural and financial barriers – and a lack of engagement with minority communities – can mean ensuring diversity in clinical trial enrollment remains challenging. While this persists, there will remain a disparity between trial participants and the patients seen in daily practice.

According to WCG SVP Sandra Smith, “The need for increased enrollment diversity will accelerate sponsor interest in opening trials at community-based sites and in supporting new investigators/sites. Rapid trial activation, bringing trial access to new participant populations, and utilization of decentralized trial components, will be critical components for trial success.”


“The average clinical trial dropout rate is 30%.”
Clinical Leader

Ultimately, successful clinical trial recruitment and patient enrollment are only half the battle. Every clinical trial must expect its share of dropouts, but if your enrollment numbers are only small to start with, then a high dropout rate is likely to impact the efficacy of your clinical study. Clinical Leader reports that a staggering 85% of clinical trials fail to retain enough patients to move forward.

Asynchronous virtual engagement and better trial enrollment

Clinical research aims to explore outcomes that reflect real-world scenarios and use cases. However, barriers to clinical trial enrollment continue to result in low participation rates and small sample sizes that ultimately do not reflect the reality of everyday practice. All too often, poor clinical trial enrollment can impede the development of potentially promising treatments or compromise the importance of quality assurance in clinical trials.

“55% of clinical trials are terminated due to patient enrollment issues.”

The last few years of digital transformation have seen pharmaceutical organizations and research institutions embrace virtual engagement methods and tools for HCP, KOL, and patient engagement, among other critical tasks. And it’s here that the life science industry can begin to address many of the most common clinical trial enrollment challenges and move towards something altogether more efficient.

Traveling long distances to fit inflexible visit schedules is no longer an issue when patients can be engaged virtually, and sessions are held asynchronously. When clinical teams can cast a wider net, underserved populations can be engaged effectively and included in treatment and drug trials with the help of tools like online translation. And by making the clinical trial process easier and less disruptive for patients, using insights management and virtual engagement platforms will also help to minimize dropouts and ensure enrollment targets are met.

For more information on troubleshooting common clinical trial challenges, read our Guide to Successful Clinical Trial Design.


A Guide to Successful Clinical Trial Design

Clinical study design can make or break a trial. It must be designed properly to mitigate or entirely eliminate such factors from confusing the results, or leading to improper conclusions. Get the basics in our guide.

3 Patient Retention Strategies for Clinical Trials Retention

Retention – the strategy and tactics designed to keep participants from discontinuing participation and dropping out – keeps a study on track and saves time, costs, and resources. What are some patient retention strategies that clinical trial teams can use to increase their chance for success?

Nature. The COVID pandemic’s lingering impact on clinical trials.
National Institutes of Health. The Internet and Clinical Trials: Background, Online Resources, Examples and Issues.
ClinEdge. Study shows that with clinical trial participation comes the burden of travel.
FDA. 2020 Drug Trials Snapshots Summary Report.
Clinical Leader. Considerations For Improving Patient Recruitment Into Clinical Trials.
WCG. Clinical research trends and insights for 2023.
National Library of Medicine. Recruitment and retention of participants in clinical studies: Critical issues and challenges.

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