Inclusion of progression criteria in external randomised pilot trials: a cross-sectional study of funding applications submitted to the NIHR Research for Patient Benefit Programme

BACKGROUND: External randomised pilot trials aim to assess whether a future definitive randomised controlled trial (RCT) is feasible. Pre-specified progression criteria help guide the interpretation of pilot trial findings to decide whether, and how, a definitive trial should be conducted. We aimed to examine how researchers report and plan to assess progression criteria in external pilot trial funding applications submitted to the NIHR Research for Patient Benefit Programme. METHODS: We conducted a cross-sectional study of progression criteria inclusion in Stage 1 (outline) and corresponding Stage 2 (full) funding applications for external randomised external pilot trials submitted to NIHR RfPB between July 2017 and July 2019. RESULTS: Of the 100 Stage 1 outline applications assessed, 95 were eligible for inclusion (of these, 52 were invited to Stage 2 full application; 43 were rejected) and 49/52 were eligible for inclusion at Stage 2 full application (of these, 35 were awarded funding; 14 were rejected). Over half of applications assessed at Stage 1 (48/95, 51%), and 73% of those assessed at Stage 2 (36/49) included progression criteria in their research plans. Progression criteria were most often reported in a stop-go format, often with additional specified factors that should be considered when determining feasibility (Stage 1 33/48, 69%; Stage 2 21/36, 58%). Recruitment and retention were the most frequent indicators of feasibility to inform progression criteria. One-third of applications provided some justification or rationale for their targets (Stage 1 16/48, 33%; Stage 2 12/36, 33%). Funding committee feedback mentioned progression criteria in over 20% of applications (Stage 1 22/95, 23%; Stage 2 11/49, 22%) to either request the addition of progression criteria or provide justification for the criteria stipulated. CONCLUSIONS: Our findings indicate that researchers do not always include progression criteria in external randomised pilot trial applications submitted to research funders. This can result in a lack of transparency in the assessment of randomised pilot trial feasibility. TRIAL REGISTRATION: Open Science Framework osf.io/89ap7, registered 29th June 2021.