Community engagement to reduce inequalities in health: a systematic review, meta-analysis and economic analysis

Background: Community engagement has been advanced as a promising way of improving health and reducing health inequalities; however, the approach is not yet supported by a strong evidence base. Objectives: To undertake a multimethod systematic review which builds on the evidence that underpins the current UK guidance on community engagement; to identify theoretical models underpinning community engagement; to explore mechanisms and contexts through which communities are engaged; to identify community engagement approaches that are effective in reducing health inequalities, under what circumstances and for whom; and to determine the processes and costs associated with their implementation. Data sources: Databases including the Cochrane Database of Systematic Reviews (CDSR), The Campbell Library, the Database of Abstracts of Reviews of Effects (DARE), the Health Technology Assessment (HTA) database, the NHS Economic Evaluation Database (NHS EED) and EPPI-Centre’s Trials Register of Promoting Health Interventions (TRoPHI) and Database of Promoting Health Effectiveness Reviews (DoPHER) were searched from 1990 to August 2011 for systematic reviews and primary studies. Trials evaluating community engagement interventions reporting health outcomes were included. Review methods: Study eligibility criteria: published after 1990; outcome, economic, or process evaluation; intervention relevant to community engagement; written in English; measured and reported health or community outcomes, or presents cost, resource, or implementation data characterises study populations or reports differential impacts in terms of social determinants of health; conducted in an Organisation for Economic Co-operation and Development (OECD) country. Study appraisal: risk of bias for outcome evaluations; assessment of validity and relevance for process evaluations; comparison against an economic evaluation checklist for economic evaluations. Synthesis methods: four synthesis approaches were adopted for the different evidence types: theoretical, quantitative, process, and economic evidence. Results: The theoretical synthesis identified key models of community engagement that are underpinned by different theories of changes. Results from 131 studies included in a meta-analysis indicate that there is solid evidence that community engagement interventions have a positive impact on health behaviours, health consequences, self-efficacy and perceived social support outcomes, across various conditions There is insufficient evidence – particularly for long-term outcomes and indirect beneficiaries – to determine whether one particular model of community engagement is likely to be more effective than any other. There are also insufficient data to test the effects on health inequalities, although there is some evidence to suggest that interventions that improve social inequalities (as measured by social support) also improve health behaviours. There is weak evidence from the effectiveness and process evaluations that certain implementation factors may affect intervention success. From the economic analysis, there is weak but inconsistent evidence that community engagement interventions are cost-effective. By combining findings across the syntheses, we produced a new conceptual framework. Limitations: Differences in the populations, intervention approaches and health outcomes made it difficult to pinpoint specific strategies for intervention effectiveness. The syntheses of process and economic evidence were limited by the small (generally not rigorous) evidence base. Conclusions: Community engagement interventions are effective across a wide range of contexts and using a variety of mechanisms. Public health initiatives should incorporate community engagement into intervention design. Evaluations should place greater emphasis on long-term outcomes, outcomes for indirect beneficiaries, process evaluation, and reporting costs and resources data. The theories of change identified and the newly developed conceptual framework are useful tools for researchers and practitioners. We identified trends in the evidence that could provide useful directions for future intervention design and evaluation.