title: Incorporating considerations of socio-economic health inequalities in evidence synthesis
Creators: name: Maden, M
Publisher: name: University of Liverpool Repository
Year: 2019

description: Interventions shown to be effective in improving the health of a population may actually widen the health inequalities gap while others reduce it. Therefore, it is imperative that all systematic reviewers consider the potential for their findings to reduce or increase health inequalities. However, challenges arising when incorporating health inequality considerations in systematic reviews relate to the nature of the evidence base, the nature of the review process, the reviewer and lack of guidance available to reviewers. The aim addressed here is how we can enable systematic reviewers to consider a priori whether, and how, an individual’s socio-economic status (i.e. their income, educational or occupational status) may moderate the effectiveness of healthcare interventions, in order to predict the likely impact on socio-economic health inequalities. Methods used to examine this aim included a mapping review of the review guidance on the conduct of systematic reviews considering health inequalities; a methodology study on the use of programme theory to inform considerations of socio-economic health inequalities in systematic reviews; a ‘best fit’ framework synthesis approach in developing a meta-framework and a worked example of meta-framework development. The mapping review found 20 review guidance documents to inform health inequality considerations in systematic reviews. The underlying assumption in the guidance was that reviewers would understand the ways in which an individual’s socio-economic status moderates intervention effectiveness. The guidance advocates the use of theory to inform health inequality considerations in systematic reviews, but offer little practical advice. The methodology study found that the use of theory in socio-economic focused systematic reviews was fragmented and ad-hoc, with little use of formal theory. 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. The meta-framework identified factors relating to the type of intervention, implementation, context, participant response, and mechanisms associated with differential effects across socio-economic groups. Methodological challenges in developing a meta-framework to inform evidence synthesis identified include; i) identification of theory, ii) selection of theory, iii) operationalisation of theory and iv) evaluation of theory. The meta-framework can inform socio-economic health inequality considerations at different stages in the review process. In particular, during question formulation, literature searching, data extraction, analyses and synthesis, and assessments of applicability. In the event of a lack of evidence of the impact of socio-economic status on differential effectiveness of health interventions, the theory-led meta-framework can ensure that reviewers base assessments of the applicability of the findings to disadvantaged populations on a posteriori reasoning rather than post-hoc assumptions. In this way, the meta-framework aims to increase the usefulness of systematic reviews in informing healthcare practice and policy.