Retention strategies in longitudinal cohort studies: a systematic review and meta-analysis

Abstract

BackgroundParticipant retention strategies that minimise attrition in longitudinal cohort studies have evolved considerably in recent years. This study aimed to assess, via systematic review and meta-analysis, the effectiveness of both traditional strategies and contemporary innovations for retention adopted by longitudinal cohort studies in the past decade.MethodsHealth research databases were searched for retention strategies used within longitudinal cohort studies published in the 10-years prior, with 143 eligible longitudinal cohort studies identified (141 articles; sample size range: 30 to 61,895). Details on retention strategies and rates, research designs, and participant demographics were extracted. Meta-analyses of retained proportions were performed to examine the association between cohort retention rate and individual and thematically grouped retention strategies.ResultsResults identified 95 retention strategies, broadly classed as either: barrier-reduction, community-building, follow-up/reminder, or tracing strategies. Forty-four of these strategies had not been identified in previous reviews. Meta-regressions indicated that studies using barrier-reduction strategies retained 10% more of their sample (95%CI [0.13 to 1.08]; p = .01); however, studies using follow-up/reminder strategies lost an additional 10% of their sample (95%CI [− 1.19 to − 0.21]; p = .02). The overall number of strategies employed was not associated with retention.ConclusionsEmploying a larger number of retention strategies may not be associated with improved retention in longitudinal cohort studies, contrary to earlier narrative reviews. Results suggest that strategies that aim to reduce participant burden (e.g., flexibility in data collection methods) might be most effective in maximising cohort retention.Electronic supplementary materialThe online version of this article (10.1186/s12874-018-0586-7) contains supplementary material, which is available to authorized users.

Retention of participants recruited to a multi-year longitudinal study via Prolific

“…A recent systematic review and meta-analysis reported average retention to longitudinal cohort studies of 73.5% (Teague et al, 2018). The retention observed within this study (76.74%) is broadly consistently with this average and compares favourability to retention observed by Palan and Schitter (2018) and Sheeran and Conner (2019) in other studies conducted on the Prolific platform with shorter follow-up periods (2 weeks and 3 months respectively).…”

“…The retention rate is particularly promising given that very low burden to researchers in managing participant retention and recontact. While we did not formally track researcher time, we estimate that management of the entire follow-up recruitment process Teague et al (2018), who reported higher retention rates in cohorts with a greater proportion of female participants and with examinations from within individual cohort studies that have reported higher attrition among male respondents (e.g. Radler & Ryff, 2010).…”

“…Given that contacting participants outside of Prolific is a breach of the terms of service, many strategies shown to be effective in increasing retention in conventional cohort designs (e.g. Teague et al, 2018;Booker, Harding, & Benzeval, 2011) are not viable in this context. Consequently, the proportion of active users on the platform at a followup timepoint provides an upper limit of a study's retention rate.…”

Instagram as a tool for study engagement and community building among adolescents: A social media pilot study

“…Most notably, 43% of the survey respondents who said they use Instagram affirmed that our study account influenced their decision to continue their participation, which aligns with the finding from Teague et al 16 that using more social media and other emerging retention strategies has been shown to strengthen retention. Though this finding was unexpected given that a substantially lower proportion of participants said they were actually following the account, it is possible that knowing the study used Instagram affected perceptions of the study being youth friendly, thereby increasing their likelihood to continue participating.…”

“…15 However, methods for innovative, technology-based engagement with study participants may need to expand as adolescents' interaction with technology evolves. In a meta-analysis of retention strategies in longitudinal cohorts, Teague et al 16 found that studies that used a greater number of "emerging retention strategies" (e.g. social media and SMS) achieved higher retention rates.…”