Factors affecting recruitment into depression trials: Systematic review, meta-synthesis and conceptual framework.

BACKGROUND:
Depression is common and clinical trials are crucial for evaluating treatments. Difficulties in recruiting participants into depression trials are well-documented, yet no study has examined the factors affecting recruitment. This review aims to identify the factors affecting recruitment into depression trials and to develop a conceptual framework through systematic assessment of published qualitative research.

METHODS:
Systematic review and meta-synthesis of published qualitative studies. Meta-synthesis involves a synthesis of themes across a number of qualitative studies to produce findings that are "greater than the sum of the parts". ASSIA, CINAHL, Embase, Medline and PsychInfo were searched up to April 2013. Reference lists of included studies, key publications and relevant reviews were also searched. Quality appraisal adopted the "prompts for appraising qualitative research".

RESULTS:
7977 citations were identified, and 15 studies were included. Findings indicate that the decision to enter a depression trial is made by patients and gatekeepers based on the patient׳s health state at the time of being approached to participate; on their attitude towards the research and trial interventions; and on the extent to which patients become engaged with the trial. Our conceptual framework highlights that the decision to participate by both the patient and the gatekeeper involves a judgement between risk and reward.

LIMITATIONS:
Only English language publications were included in this review.

CONCLUSIONS:
Findings from this review have implications for the design of interventions to improve recruitment into depression trials. Such interventions may aim to diminish the perceived risks and increase the perceived rewards of participation.