Recruitment and retention are among the most persistent operational challenges in clinical trials, directly influencing timelines, budgets and data quality. In the UK, delays in participant enrolment and high attrition remain a significant operational concern across UK trials, even where median retention rates appear reasonably high. Ultimately, this threatens study feasibility and limits the generalisability of results. While scientific design, regulatory approval and feasibility assessments are given extensive attention, the lived experience of participants is often treated as secondary. Yet it is this experience, shaped by burden, communication, accessibility and trust that directly determines whether a study reaches its targets on time and with high-quality data.

A comprehensive review of publicly funded UK RCTs found that only about 63% achieved their final stated recruitment target, and 30% of trials revised their target.1 The median retention of participants (valid primary outcome data) across studies was approximately 88%. Turning to industry-sponsored studies, the ABPI reports that between 20–30% of UK industry clinical trials fail to recruit the agreed participant numbers within the planned timeframes