Recruitment and retention rates in behavioral trials involving patients and a support person: a systematic review.

Background: Recruitment and retention challenges impede the study of behavioral interventions among patient-support person dyads.

Purpose: The aim of the study was to characterize recruitment and retention rates of behavioral interventions involving dyads.

Methods: Using PRISMA guidelines and with the guidance of a medical librarian, we searched Medline, EMBASE, Cochrane Controlled Trials, PsycInfo, and CINAHL from inception until July 2011. Eligible articles involved RCTs of behavioral interventions targeting adult patients with a non-psychiatric illness and a support person. Sample and study characteristics, recruitment and retention strategies, and recruitment and retention rates were abstracted in duplicate. Quality of reporting was determined on a 5-point scale. Due to the heterogeneity in data reporting and missing data, a narrative synthesis was undertaken.

Results: 53 unique studies involving 8081 dyads were included. 9 studies were ascertained to have a "high quality" of reporting. A majority of the studies did not report target sample size, time to complete recruitment, and sample sizes at each follow-up time point. Strategies employed to recruit support persons were rarely reported. 16 studies did not report the number of dyads screened. The mean recruitment rate was 51.2% (range: 4.3%-95.4%), and mean retention rate was 77.5% (range: 36%-100%).

Conclusions: Details regarding recruitment and retention methodology were sparse in these interventions. Where available, data suggests that resources need to be devoted towards recruitment of sample but that retention rates are generally adequate.