How well does enrolment in pilot and feasibility trials predict enrolment in subsequent pivotal trials? A registry-based analysis

Pilot and feasibility trials are conducted for multiple reasons, such as assessing the logistics of the protocol, evaluating the appropriateness of instruments, and examining aspects related to enrolment. A number of studies have used bibliometric approaches to understand the extent to which pilot and feasibility studies inform subsequent clinical trials. In broad terms, bibliometric approaches have typically identify published trials to extract the enrolment information in order to estimate absolute recruitment and enrolment metrics (e.g., consent rates, randomization rates). Using a registry like ClinicalTrials.gov provides additional information on prespecified recruitment goals, such as the original intended number of participants. This contextual information is crucial in evaluating the "success" of recruitment efforts. In this study, we will explore whether enrolment success pilot and feasibility trials translate into enrolment success in their subsequent full-scale trials. We will conduct a bibliometric-like review of ClinicalTrials.gov to identify a cohort of pilot and feasibility trials along with their corresponding full-scale trial. Two key variables of interest are the trial's planned enrolment count and the trial's actual enrolment count. We will interpret the ratio between these two variables as the degree of success in achieving the enrolment target. We will use regression-based methods to analyze the predictive relationship between enrolment success in pilot and feasibility trials and enrolment success in subsequent full-scale trials.