The relationship between health impact assessment and healthy public policy : a critical realist investigation

BackgroundHealth impact assessment (HIA) and Healthy public policy (HPP) have been used interchangeably in discussions about the increasing interest in influencing public policy to improve health and health equity. This has sometimes conflated expectations about what each approach can deliver, limited understanding of the relationship between them and failed to identify wider influences on the practice of each. Critical realist methodology was used to identify and explain the factors underpinning the relationship between HIA and HPP.Methodology and MethodNine interviews and a workshop were held with international practitioners working in HIA and HPP. First, the empirical data was analysed using established critical realist analytic questions. Second, the empirically generated results were re-described using institutional public policy theory, specifically Howlett et als Policy cycles and subsystems theory which explains how actors (emphasising people and their relationships), ideas (emphasising content) and institutions (emphasising systems) all play roles in progressing HIA and HPP. FindingsEmpirically HIA and HPP were demonstrated to be separate yet overlapping entities, each of which has essential and contingent characteristics. Public policy presupposes both HIA and HPP, and five public policy characteristics were identified as influences. Seven other contingent factors influence HIA and HPP and the relationship between them. Against theory HPP is largely concerned, tactically, with agenda-setting and HIA, technically and tactically, with policy formulation. Focussing in on HIA, particular emphasis is placed on substantive and procedural dimensions of public policy making. The findings include the institutional structures and mechanisms acting as conditions surrounding HIA for HPP, how the essential features of HIA fit with public policy making, and how the essential features of HIA as a policy formulation instrument operate and can be strengthened. Three propositions are developed which provide summary explanations for these features. Conclusion Separating the essential elements of HIA and HPP from contingent influences helps practitioners and researchers identify what can be directly controlled or changed to improve practice, and what else needs to be planned for as contingencies largely outside the control of HIA or HPP practitioners. Further case specific research is recommended to test the findings