Identified barriers to progression of a feasible external pilot trial to a future trial
RECRUITMENT
Of the 80 respondents across all four surveys who stated that their future trial would be feasible or feasible with changes to the trial design (80/89, 90%), 18 (18/80, 23%) indicated that they did not intend to conduct a future definitive trial. Using survey branching logic these respondents were invited to provide reasons for why they did not intend to conduct a definitive trial (offered by 17/18, 94%), summarised in Table Reported barriers to progression of feasible external pilot trialsResponses presented were reported by 17 respondents who considered their external pilot trial to be feasible or feasible with changes, but did not intend to conduct a future definitive trialMost participants provided more than one reasonFunding considerations, such as whether funding for the definitive trial would be available and sufficient, were the most frequently reported reason for not doing a definitive trial, reported by six respondents (6/17, 35%). Changing Chief Investigator (CI) priorities was another more frequent barrier to external pilot trial progression (5/17, 29%): five respondents reported that they had decided to pursue other research interests instead of a definitive trial, with two stating that their external pilot trial had formed part of their PhD, and that they were not resourced to take it forward. Three respondents (3/17, 18%) described how changes to the healthcare context e.g. service delivery, implementation of other interventions, or the impact of COVID-19 meant that they could not justify a definitive trial. Two respondents described that they would not pursue a definitive trial because there was no indication of efficacy, and one described how efficacy had since been proven in a different fully powered RCT (2/17, 12%). Other barriers included the number of resources required (2/17, 12%), the definitive trial sample size was too large (1/17, 6%), further feasibility assessment was needed (1/17, 6%), a lack of interest in the intervention (1/17, 6%), challenges with recruitment (1/17, 6%), reliability of data collection (1/17, 6%) and unsuccessful stakeholder collaborations (1/17, 6%).