Towards a theory-led meta-framework for considering socioeconomic health inequalities within systematic reviews

OBJECTIVE: To develop a theory-led framework to inform reviewers' understanding of what, how and why healthcare interventions may lead to differential effects across socio-economic groups. STUDY DESIGN AND SETTING: A meta-framework approach combined two theoretical perspectives (socio-economic health inequalities and complex interventions) into a single framework to inform socio-economic health inequality considerations in systematic reviews. RESULTS: Four theories relating to complexity within systematic reviews and 16 health inequalities intervention theories informed the development of a meta-framework. Factors relating to the type of intervention, implementation, context, participant response and mechanisms associated with differential effects across socio-economic groups were identified. The meta-framework can inform; reviewer discussions around how socio-economic status can moderate intervention effectiveness during question formulation, approaches to data extraction and help identify a priori analysis considerations. CONCLUSION: The meta-framework offers a transparent, practical, theory-led approach to inform a programme theory for what, how and why interventions work for different socio-economic status groups in systematic reviews. It can enhance existing guidance on conducting systematic reviews that consider health inequalities, increase awareness of how socio-economic status can moderate intervention effectiveness and encourage a greater engagement with theory throughout the review process.