Behavioural approaches to recruitment and retention in clinical trials: a systematic mapping review.

A range of behavioural approaches have been applied to recruitment and retention to trials. The multitude of recruitment research here is consistent with trials research generally and emphasises the need for research into retention. Authors report target behaviours minimally, which is not conducive to replication. Further research should build on lessons here, such as clearly specifying behaviours. Increased methodological rigour and transparency will lead to robust evidence bases and less research waste in poor recruitment and retention. Overall, trials informed by behavioural approaches promises to be efficient and more participant focused.