Undertaking studies within a trial to evaluate recruitment and retention strategies for RCTs: lessons learnt from the PROMETHEUS research programme

Adwoa Parker, Catherine Ellen Arundel, Laura Kate Clark, Elizabeth Coleman, Laura Doherty, Catherine Elizabeth Hewitt, David Beard, Peter Bower, Cindy Cooper, Lucy Culliford, Declan Devane, Richard Emsley, Sandra Eldridge, Sandra Galvin, Katie Gillies, Alan Montgomery, Chris Sutton, Shaun Treweek, David John Torgerson

Research output: Contribution to journalArticlepeer-review


Randomised controlled trials (‘trials’) are susceptible to poor participant recruitment and retention. Studies Within A Trial (SWATs) are the strongest methods for testing the effectiveness of strategies to improve recruitment and retention. However, relatively few of these have been conducted.

PROMoting THE USE of Studies Within A Trial (PROMETHEUS) aimed to facilitate at least 25 SWATs evaluating recruitment or retention strategies. We share our experience of delivering the PROMETHEUS programme, and the lessons learnt for undertaking randomised SWATs.

A network of 10 Clinical Trials Units (CTUs) and one primary care research centre committed to conducting randomised controlled SWATs of recruitment and/or retention strategies was established. Promising recruitment and retention strategies were identified from various sources including Cochrane systematic reviews, the SWAT Repository, and existing prioritisation exercises,
which were reviewed by patient and public (PPI) members to create an initial priority list of seven recruitment and eight retention interventions.
Host trial teams could apply for funding and receive support from the PROMETHEUS team to undertake SWATs. We also tested the feasibility of undertaking coordinated SWATs, across multiple host trials simultaneously.

CTU-based trials recruiting or following up participants in any setting in the UK were eligible.

CTU-based teams undertaking trials in any clinical context in the UK.

Funding of up to £5,000 and support from the PROMETHEUS team to design, implement, and report SWATs.

Main outcome measures
Number of host trials funded
Original languageEnglish
JournalHealth Services and Delivery Research
Publication statusAccepted/In press - 16 Dec 2022

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