Modelling the health and economic impact of built environment interventions

Abstract

BackgroundIn Australia, over half (57%) of the adult population is not meeting national physical activity guidelines. This is concerning, given that physical inactivity is a well-known preventable risk factor for several chronic diseases. Physical inactivity was estimated to cost Australians 124,000 disability-adjusted life years annually (2015) and a significant proportion of the healthcare budget. Furthermore, physically inactive people are more likely to be absent from work, underperform, or both, impacting negatively on their career prospects and national output.In Australia, the majority of the people live in urban areas (90%) and population projections show significant growth in its main cities. Hence, shaping cities such that they contribute to healthy behaviours is key to building a healthy and prosperous population. The research community can contribute to a healthy expansion of Australian cities by producing context specific evidence for the potential of the built environment to enhance population health. AimsThe overall aim of this thesis is to contribute to the evidence on the potential health and economic benefits of investing in built environments that are supportive of physical activity. ii MethodsTwo systematic reviews were conducted to address RQ 1 and 3, applying rigorous methods to ensure objectivity in the selection of literature. For RQ 2, 4 and 5, a multi-state life-table modelling approach, developed as part of the Assessing Cost Effectiveness in Prevention study, was updated and expanded. For RQ 2, the model was used to estimate health-adjusted life years (HALYs) and healthcare costs attributable to changes in exposure to attributes of the built environment within the neighbourhood area. For RQ 4, the methods applied to answer RQ 2 were expanded, and describe a method to estimate the health benefits of physical activity that can be included in cost-benefit analyses of built environment interventions. Lastly, the model is significantly expanded for RQ 5, with the addition of exposure to air pollution and road trauma. These are added to physical activity to assess the likely overall health impact of Brisbane achieving its proposed travel targets (15% of trips walking, 5% cycling and 14% using public transport). Main findingsFor the Australian setting, recent evidence indicates that features of the built environment in neighbourhoods, including the availability of destinations and diverse use of lands, can support physical activity, and especially walking (RQ 1). Improvements in the built environment within the neighbourhood can therefore significantly contribute to population health (RQ2). However, it is uncertain whether improved health will translate into healthcare costs savings, as initial reductions may be offset by healthcare costs in added life years. The evidence demonstrating the economic merit of active transport interventions has been growing markedly over the last 10 years (RQ3). Cost-benefit analysis is a widely used method for the economic appraisal of interventions ...