Why Clinical Trial Participation Fails at Every Level
We tend to assume clinical trials fail because the science doesn't hold up. In reality, more than half never get the chance to prove whether it does. According to a global data analysis by the NIH, 55% of terminated trials in the Clinical Trials Database were a result of not meeting enrollment demands. Further, more than 80% of trials fail to meet their initial, planned enrollment timelines, often resulting in extensions or the addition of new study sites. To put it further, the average enrollment rate for Phase III and Phase IV trials is less than 40%. (See more information on clinical trial phases here)
Like many issues in healthcare, barriers to participation in clinical trials are multi faceted and intertwined. As one study by the NIH that outlines barriers to cancer clinical trials describes, these barriers exist across different levels. Patient, provider, clinical, and institutional, and they build on top of one another. No single barrier explains low participation. Together, they make it the substantial problem that it is.
At the patient level, barriers include beliefs/attitude or mistrust, distance to trial site, health insurance coverage, language, and immigration status. One patient has stated fearing "...being treated like a guinea pig. And the number of times that I hear about that can be surprising, and it's more profound with minority groups, because there's an inherent trust issue about how they're being treated, equitably or not” (Kumar). This insight reveals not just general mistrust towards clinical trial experimentation, but a deeper mistrust rooted in the historical, disproportionate mistreatment of non-white groups in the healthcare industry.
On the healthcare provider side, barriers to clinical trial participation include limited awareness/knowledge of ongoing clinical trials, time constraints, and non-cooperation of colleagues. In many cases, providers do not get enough facetime with their patients to thoroughly discuss a trial and their patient’s eligibility to reach the enrollment step (Kumar). Similarly, a study addressing challenges within the Veterans Health Administration (VHA) in referring and enrolling patients found that providers struggle to manage the referral process for trials outside the VHA system and face challenges identifying available clinical trials.
These provider specific challenges directly affect patients as research suggests that patients rely heavily on their providers for information about available clinical treatment options. For example, a provider’s time constraint and inability to discuss a clinical trial in-depth may exacerbate a patient’s mistrust in clinical trials.
Clinical-level barriers to trial participation include strict eligibility criteria and complex trial design. In isolation, these challenges might be easily mitigated through solutions like AI patient-trial matching or streamlined informed consent models. However, when layered on top of patient, provider, and institutional barriers, even well-designed clinical solutions become difficult to implement effectively.
Lastly, challenges are identified at the institutional and structural level. Most challenges in Kumar et al. were revealed at this level, including limited logistic support from staff, insufficient funding, and constraints related to the Institutional Review Board (IRB), the entity responsible for approving and rejecting clinical studies. Structural barriers especially affect minority groups underrepresented in clinical research. Research published in February 2026 identified excessive data collection as a growing contributor to participant burden. Much of this data may lack direct relevance to a study's primary objectives and may never be analyzed, yet the burden of providing it disproportionately affects minority ethnic groups, people with caring responsibilities, and older adults.
The abundance of barriers across multiple levels of the clinical trial system makes clear that low participation requires a comprehensive, unified solution. At Find My Clinical Trial, we are actively working with patients, providers, and clinical trial staff to build that solution. We are committed to being patient-centered while acknowledging that low participation stems from far more than mistrust or a lack of awareness on the patient's side.
Written by Genevieve Statzinger
Sources:
Desai M. (2020). Recruitment and retention of participants in clinical studies: Critical issues and challenges. Perspectives in clinical research, 11(2), 51–53. https://doi.org/10.4103/picr.PICR_6_20
KFF. (2024). How history has shaped racial and ethnic health disparities: A timeline of policies and events. https://www.kff.org/racial-equity-and-health-policy/how-history-has-shaped-racial-and-ethnic-health-disparities-a-timeline-of-policies-and-events/
Kumar, G., Chaudhary, P., Quinn, A., & Su, D. (2022). Barriers for cancer clinical trial enrollment: A qualitative study of the perspectives of healthcare providers. Contemporary clinical trials communications, 28, 100939. https://doi.org/10.1016/j.conctc.2022.100939
Law, E., & Chatfield, K. (2026). The undue burdens of clinical trial participation: implications for equity, diversity, and inclusion. Trials, 27(1), 115. https://doi.org/10.1186/s13063-026-09540-7
Monreal, I., Chappell, H., Kiss, R., Friedman, D. R., Akesson, J., Sae-Hau, M., Szumita, L., Halwani, A., & Weiss, E. S. (2025). Understanding the barriers to clinical trial referral and enrollment among oncology providers within the Veterans Health Administration. Military Medicine, 190(3–4), e891–e898. https://doi.org/10.1
Weinberg, A. D., Cooper, H. P., Mejia, N. I., & Spiker, C. A. (2004). Attitudes of primary care physicians and specialists about cancer clinical trials: a survey of Texas physicians. Texas medicine, 100(4), 66–72.