Prespecified progression criteria can inform the decision to progress from an external randomised pilot trial to a definitive randomised controlled trial.
We assessed the characteristics of progression criteria reported in external randomised pilot trial protocols and
results publications, including whether progression criteria were specified a priori and mentioned in prepublication
peer reviewer reports.
We searched four journals through PubMed: British Medical Journal Open, Pilot and Feasibility Studies, Trials and Public Library of Science One. Eligible publications reported external randomised pilot trial protocols or results, were published between January 2018 and December 2019 and reported progression
criteria. We double data extracted 25% of the included publications. Here we report the progression criteria characteristics.
We included 160 publications (123 protocols and 37 completed trials). Recruitment and retention were the most frequent indicators contributing to progression criteria. Progression criteria were mostly reported as distinct thresholds (eg, achieving a specific target;
133/160, 83%). Less than a third of the planned and completed pilot trials that included qualitative research reported how these findings would contribute towards
progression criteria (34/108, 31%). The publications seldom stated who established the progression criteria (12/160, 7.5%) or provided rationale or justification for progression criteria (44/160, 28%). Most completed pilot
trials reported the intention to proceed to a definitive trial (30/37, 81%), but less than half strictly met all of their progression criteria (17/37, 46%). Prepublication peer reviewer reports were available for 153/160 publications (96%). Peer reviewer reports for 86/153 (56%) publications mentioned progression criteria, with peer reviewers of 35 publications commenting that progression criteria appeared not to be specified.
Many external randomised pilot trial
publications did not adequately report or propose prespecified progression criteria to inform whether to proceed to a future definitive randomised controlled trial.
Bibliographical noteFunding This work was supported by Medical Research Council Doctoral Training Partnership funding (grant number MR/N013468/1) awarded to KM.
Data Availability StatementData availability statement
Data are available upon reasonable request. Data from this review will be included in a DPhil thesis published open access through
the Oxford University Archive upon KM’s DPhil completion.
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