Strategies for recruiting participants underrepresented in clinical research: A scoping review

Despite the 1993 National Institutes of Health Revitalization Act's mandate regarding underrepresented groups in clinical research, broad representation in clinical research is still lacking, making generalizability more difficult. Additionally, the extent of research that defines actionable strategies to encourage participation of a variety of patients in clinical research is unclear. This scoping review aimed to map evidence-based strategies for clinical research recruitment of underrepresented groups identified in the 1993 NIH Revitalization Act. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) framework, articles were included if they: (1) reported strategies used for adult patient recruitment, selection, or enrollment in human subjects research; (2) focused on recruiting underrepresented groups; (3) took place within the United States; and (4) were either randomized controlled trial designs, prospective or retrospective cohort studies, cross-sectional designs, quasi-experimental designs, or qualitative studies. We selected 67 articles which reported efforts to recruit underrepresented groups to have broad generalizability of treatment effects. The most successful strategies reported in the literature included recruiting in clinical/healthcare and community settings; using electronic health records and health/disease registries to identify patients; snowball sampling; newspaper and social media advertising; and mass mailing of letters. This paper offers a comprehensive review of the evidence-based recruitment strategies and materials for recruitment of groups that are historically underrepresented in a variety of clinical research studies, thus providing a set of recommendations for future researchers who aim to conduct scientifically rigorous clinical research studies with broad patient samples.