A systematic review of randomized trials for engaging socially disadvantaged groups in health research: A distillation approach

Research that fails to include sufficient representation from socially disadvantaged groups cannot make strong inferences about those groups. This relative lack of knowledge poses theoretical and clinical problems for health research. More effective community engagement with socially disadvantaged groups is often proposed as a way to increase research engagement. However, community engagement is a heterogeneous construct, including everything from how participants are contacted to whether researchers work with an organization within the community. Further, community engagement efforts vary widely in their effectiveness in recruiting and retaining participants from socially disadvantaged groups. Therefore, some types of community engagement may be more effective than others. We conducted a systematic review of randomized controlled trials attempting to increase recruitment or retention of socially disadvantaged groups. We then applied systematic distillation procedures to examine which components of community engagement interventions were associated with successful recruitment or retention outcomes. Generally, we found research process related variables (e.g. having a systematic contact plan) most frequently differentiated effective vs. ineffective recruitment or retention outcomes. Partial associations between components in effective interventions, including negative associations, were descriptively stronger than partial associations in the ineffective interventions, indicating targeted interventions may be more effective than more generalized interventions. The literature was also relatively sparse and at unclear-to-high-risk for bias. Future pre-registered, research process-oriented, and targeted recruitment and retention interventions may increase the research participation of socially disadvantaged groups in health research.