Community-based participatory research to engage disadvantaged communities: Levels of engagement reached and how to increase it. A systematic review.

Community-based participatory research (CBPR) is one of the most used community engagement frameworks to promote health changes in vulnerable populations. The more a community is engaged, the more a program can impact the social determinants of health. The present study aims to measure the level of engagement reached in randomized controlled trials (RCTs) using CBPR in disadvantaged populations, and to find out the CBPR components that better correlate with a higher level of engagement. A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Embase, Web of Science, MEDLINE, Cochrane and Scopus databases were queried. Engagement level was assessed using the revised version of IAP2 spectrum, ranging from "inform" to "shared leadership" . Fifty-one RCTs were included, belonging to 36 engagement programs. Fourteen CBPR reached the highest level of engagement. According to the multivariate logistic regression, a pre-existing community intervention was associated with a higher engagement level (OR = 10.08; p<0.05). The variable "institutional funding" was perfectly correlated with a higher level of engagement. No correlation was found with income status or type of preventive programs. A history of collaboration seems to influence the effectiveness in involving communities burdened with social inequities, so starting new partnerships remains a public health priority to invest on. A strong potentiality of CBPR was described in engaging disadvantaged communities, addressing social determinants of health. The key findings described above should be taken into account when planning a community engagement intervention, to build up an effective collaborative field between researchers and population.