A Qualitative Scoping Review of Early Terminated Clinical Trials Sponsored by the Department of Veterans Affairs Cooperative Studies Program from 2010-2020.

Increasing interest has been given to the risks and benefits of terminating large clinical trials before reaching pre-specified targets, as such decision can greatly impact the implementation of findings. Department of Veterans Affairs Cooperative Studies Program (VA CSP) is a research infrastructure dedicated to conducting high-quality clinical research. A scoping review was performed to characterize barriers preventing the attainment of pre-specified recruitment, statistical power, or sample size targets in VA CSP trials. A trial was eligible for inclusion if the trial was sponsored by the VA CSP, primary findings were published within the last 10 years, and a decision was made to terminate enrollment or follow-up prior to meeting a priori recruitment or endpoint targets. Following screening, a total of 29 clinical trials were identified. In 11 trials (37.9%), a decision was made to terminate the trial early. The most common reason for early termination was related to under-recruitment (N=5). Other reasons included early detection of safety signals (N=2), futility (N=1), and benefit (N=1). Under-recruitment can lead to underpowered study results, which may result in a failure to detect a true effect and hinder implementation of trial findings. This review highlights recruitment as a critical facet of trial conduct which may hinder the production of high-quality data, and thus warrant additional attention. Solutions to enhance recruitment now implemented by the VA CSP, including dedicated enrollment infrastructure and screening facilitated by informatics approaches, show promise in reducing this cause for early termination.