Incorporating an equity perspective in systematic reviews of interventions: potential methodological approaches

Health inequities are unnecessary, avoidable and unjust differences in health across social groups. Addressing them is a priority for governments and health systems worldwide, requiring not only specific interventions targeting inequity but also embedding equity across all decision-making. Systematic reviews of interventions underpin health decision-making and could, therefore, be a key mechanism to address inequities, but most reviews are limited in their approach to considering equity and often only conclude data for subgroup analyses are unavailable. While some guidance is available, it largely focuses on reviews of interventions specifically seeking to reduce inequities and is published in disparate literature. We describe approaches to incorporate an equity perspective relevant to all systematic reviews of interventions, even when equity is not the primary review focus.Consideration of equity may be needed at all stages of the review process. Planning the review involves examining theory, using logic models, involving relevant people and organisations, and considering if additional sources of evidence are needed. Investigating the data requires examining the external validity of primary studies, including who was involved in the primary studies, and the reach of interventions. The synthesis process includes selecting appropriate analysis, considering the implications of reporting absolute or relative equity effects of the intervention, exploring and understanding mechanisms and assessing certainty of the evidence in relation to equity. Interpreting results involves linking theory with evidence and discussing implications and limitations. We hope this article helps review authors make best use of the available evidence to incorporate equity into systematic reviews.