A RE-AIM Evaluation of Lay Advisor Interventions to Improve Hypertension Outcomes - A Systematic Review

Context: Lay advisor interventions improve hypertension outcomes, especially in vulnerable populations. However, the incremental benefit of adding these interventions, and factors that could inform their widespread implementation, are unknown. Objective: Inform real-world choices about implementation of lay advisor hypertension interventions. Methods: We systematically searched several databases, including Medline, CINAHL, SCOPUS, from January 1, 1980 to December 2020. We included all study designs of hypertension interventions delivered solely by a lay advisor. Search terms for lay advisors included peers, community health workers, barbers, and faith-based activists. Studies of lay advisor interventions combined with other health professional interventions were excluded. Two independent reviewers coded eligible articles using a validated data extraction tool based on the Reach, Efficacy, Adoption, Implementation, Maintenance (RE-AIM) framework. Results: Of 5986 unique citations, 21 were eligible for inclusion. Most studies showed improvements in hypertension outcomes, but outcomes predominantly were measured shortly after intervention completion. Inclusion/exclusion criteria and lay advisor recruitment and training were usually well-described, and primary outcomes were reported. Participation rates were infrequently reported. None reported adverse outcomes. Only 14% (3 of 21) of studies reported qualitative assessments. External validity domains of adoption, implementation, and maintenance were rarely reported. In the adoption domain, no study reported comparisons of delivery and non-delivery settings or staff representativeness. Presence of previous lay advisor programs in the community improved adoption and implementation. One study mentioned costs of implementation for maintenance. Conclusion: Few studies have examined the incremental effectiveness of adding a lay advisor intervention for hypertension outcomes, most show improvement. Indicators of external validity of lay advisor interventions are not well-reported. Future research designs should improve reporting across RE-AIM dimensions, particularly indicators of external validity, including qualitative assessments.