Evidence for the effectiveness of health impact assessment in spatial planning on health outcomes: a systematic review and stakeholder involvement from a UK perspective

Health Impact Assessment (HIA) is a decision support method used for evaluating the impact of actual or planned developments on health and wellbeing, including the wider determinants of health. There is a lack of evidence on the effectiveness of HIA in achieving health benefits in England, and no statutory requirement for the use of HIA. The aim of this review was to undertake an evidence synthesis and use stakeholder consultation to understand the relevant factors and mechanisms by which HIA may effectively influence population health outcomes. Systematic review and stakeholder consultation. We used systematic searches of eight academic databases and supplementary citation and reference list searches of included papers focusing on UK literature. We also identified any potentially relevant UK grey literature that was in the public domain. We extracted key data from the papers and synthesised the data thematically. We developed a typology of factors and themes. We involved a UK wide stakeholder group of UK planners, local and national government public health specialists, academics, and commercial HIA providers (n = 38 in total) in two workshops to help us to identify grey literature sources, interpret the evidence, and consider the potential for developing a statutory requirement for the use of HIA. From 5117 unique records we considered 147 full texts from databases. We also identified 58 grey literature sources. Nineteen UK studies met inclusion criteria. The data themes were grouped into three categories: (1) Who to involve: Teamwork – health and planning n = 9; Links with commercial developers n = 2; Community involvement n = 2; Wider stakeholder involvement n = 4. (2) What is needed: Resources n = 5; Knowledge and understanding n = 6; Training n = 1; National policy and guidance n = 10; Evidence base n = 4. (3) Aspects of the appraisal: Appraisal timings/approach n = 6; Outcome timescales n = 1; Health definitions n = 7; Quantifying impact n = 2. Our final stakeholder workshop identified the challenges in using existing frameworks to develop a statutory requirement for England including the lack of national policy imperative, and the challenges in developing an effectiveness evidence base. We were not able to link the use of HIA in spatial planning directly to UK health outcomes. Evidence exists which could inform the development of a statutory requirement for conducting HIA in spatial planning in England. However, this evidence is not able to link the use of HIA in spatial planning directly to health outcomes. The qualitative themes identified in our review could however inform future discussion about the feasibility of developing the evidence base to include direct measures of health. A key challenge is motivating stakeholders to engage with developing the evidence base. It is also challenging to see how an evidence base could develop without a national policy requiring the use of HIA in the spatial planning process. In order to generate appropriate data to demonstrate the effectiveness of HIA in terms of health improvement, it might first be necessary to make them an explicit requirement of the planning process.