Planning for successful participant recruitment and retention in trials of behavioural interventions: Feasibility randomised controlled trial of the Wrapped intervention

Randomised controlled trials (RCTs) must have sufficient power if planned analyses are to be performed and strong conclusions drawn. A prerequisite of this is successful participant recruitment and retention. Designing a comprehensive plan for participant recruitment and retention prior to trial commencement is recommended, but evidence concerning successful strategies, and how to go about developing a comprehensive plan, is lacking. This paper reports on the application of a six-stage process to develop a recruitment and retention strategy for a future RCT. Stage 1) Rapid evidence review: strategies used in previous trials were identified through database searching. This informed Stage 2) PPI workshop: workshops with public and patient involvement (PPI) group were used to select a sub-set of these strategies based on their potential to be successful and acceptable with the target audience. Stage 3) Focus groups with the target audience: the sub-set was refined through feedback from 15 young people (data subjected to content analysis). Strategies the PPI and focus groups mutually agreed upon proceeded directly to Stage 5; those without consensus proceeded to Stage 4. Stage 4) PPI workshop: PPI members voted on the remaining strategies; those without consensus were discarded. Stage 5) Observation of strategies during feasibility RCT (fRCT): the retained set of strategies were observed in practice in a fRCT in which recruitment and retention data and qualitative feedback from participants was collected. Stage 6) PPI workshop: the fRCT findings were reviewed and strategies for use in the future RCT were finalised. The finalised strategy included set of adverts; schedule of financial incentives; instructions to send survey invite by email, one prompt by SMS prior to data collection, and up to three SMS reminders; procedure to keep participants engaged (e.g., newsletters, personalisation of communications); and procedure if participants fail to complete a research activity (follow-up email/phone call).Author summary: To draw firm conclusions, all randomised controlled trials (RCTs) must successfully recruit and retain participants. We followed a six-stage process to develop a recruitment and retention strategy for a future RCT. This involved a rapid review of evidence to identify strategies used by other randomised controlled trials (stage 1), four workshops with a public and patient involvement (PPI) group who discussed and refined the strategies (with the target sample in mind) and then cast votes to determine which should be taken forward (stages 2, 4 and 6), focus groups with the target sample (15 young people aged 16–24 years) to get direct feedback on evolving strategies (stage 3), and observation of the strategies during a feasibility RCT (stage 5). Our finalised strategy set out the recruitment adverts to be used (highlighting the value of participation, e.g., financial reward), methods for keeping participants engaged (e.g., personalisation, newsletters), the schedule of voucher payments, the frequency and mode of data collection invites and reminders (one invite, up to three reminders, email and SMS), and actions to minimise non-response (email/telephone follow-up). The process we took, and the strategies produced, may be of interest to others preparing to run a RCT.