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

OBJECTIVES: To identify studies that applied behavioural approaches to issues of recruitment and/or retention to trials; to describe these approaches; and to identify gaps for future research. DESIGN: Systematic mapping review of research undertaken in clinical trials within peer-reviewed sources. Review participants were individuals involved in clinical trials, including trial staff, participants, potential participants and former participants. DATA SOURCES: MEDLINE, EMBASE, CINAHL, ERIC, PsycINFO, Web of Science and ASSIA from inception to 15 January 2020 with no date or language restrictions. ELIGIBILITY CRITERIA: Studies within the context of clinical trials reporting the barriers/facilitators to recruitment and retention, or developing/evaluating solutions to said barriers/facilitators, using a behavioural approach. RESULTS: 31 articles were included. Recruitment-focused studies (n=22, 71%) represented the majority. Studies tended to focus on participant behaviours (n=22, 71%). Underserved populations (n=11, 35%) were a notable subset of studies. Most studies (n=23, 74%) were exploratory but those that evaluated interventions (n=8, 26%) often did so within underserved populations (n=6). A majority of studies (n=30, 97%) did not specify their behaviours consistent with guidelines from behavioural scientists. The most used approaches were social cognitive theory (n=8, 26%), the theory of planned behaviour (n=6, 19%) and the theoretical domains framework (n=5, 16%). CONCLUSIONS: 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.