How to improve participant compliance and retention in clinical trials：A Scoping Review

Abstract

Background: The reliability of results can be compromised when subsets of participants who remain on a study differ from those who drop out. Although recent studies have investigated strategies for improving compliance and retention , there has been very little investigation of process factors, regardless of the type of literature and the publication date. factors that may influence how and why compliance and retention may be successful (or not).Aim: To identify process factors that may influence participant compliance and retention in clinical trials, and potential strategies to improve the compliance and retention, from published studies, grey literature, and the reference lists of included articles to facilitate future design and implementation of trials.Methods : Six databases and two clinical trial registries were searched on November 29, 2019. Surveys, interviews, retrospective data analyses, theoretical research, reviews and clinical studies aiming at investigating factors and potential strategies were included. Data synthesis followed an iterative process to develop a list of process factors and potential retention strategies.Results were presented mainly as texts, including visualization using word cloud, and descriptive data.Results: 182 publications were included in this review, composed of 58 retrospective reflection of RCTs based on 1,132 clinical trials with 177804 participants, 27 implementation researches, 22 theoretical researches, 20 interviews, 18 surveys, 17 randomized controlled trials, 8 literature reviews, 5 systematic review and meta analysis, 3 mixed methods researches, 2 case report, 1 meta-ethnographic synthesis and 1 cohort study. We identified 70 process factors that may affect the compliance and retention . The most commonly addressed factors were age, education, economy, trust in clinical trials, supporting from surrounding people, safety concerns and effectiveness. We found 42 potential strategies to improve compliance and retention. Strategies reported most frequently were that researchers should pay attention to the changes on participants' psychological condition, try their best to build good relationships, provide some compensation and educate the participants about compliance and retention . Conclusion：These factors that may affect the compliance and retention can help researchers predict participants who are less likely to adhere and develop screening tools to find efficiently their suitable participants. These potential strategies that may improve the compliance and retention.