The contribution of walkability to geographic variation in physical activity, high body mass and psychosocial distress in Sydney, Australia

Abstract

Improving the walkability of built environments to promote healthy lifestyles is increasingly considered in urban development plans. This thesis investigated if walkability in Sydney, Australia, was associated with physical activity, high body mass and psychosocial distress when measured at the aggregate postal area level, and whether walkability contributed to geographic variation in health outcomes at this scale. Walkability indexes using residential density, intersection density, land use mix, with and without retail floor area ratio were calculated at the Census Collection District level for Sydney and compared for reliability, latent variable structure, and predictive validity for utilitarian walking using travel to work data from the 2006 Australian Census. An abridged index without retail floor area ratio retained 87% of the variability in a full index including retail floor area ratio and predicted increases in odds of utilitarian walking to work with increasing walkability. The abridged index was aggregated to postal areas to match the spatial unit of health data from Sydney respondents to the 45 and Up Study baseline questionnaire (2006–2010). Cross-sectional associations between walkability and prevalence of health-enhancing physical activity (including walking), high body mass, and psychosocial distress at the postal area level were investigated using Bayesian spatial regressions adjusted for individual-level factors. Prevalence of health-enhancing walking and total physical activity were higher in high walkability postal areas, while prevalence of overweight and obesity were lower in medium high and high walkability postal areas. Psychosocial distress was not associated with walkability at the postal area level. This thesis demonstrated the utility of spatial analysis for walkability research and planning, and illustrates how walkability indexes can inform population-level action aimed at increasing physical activity and reducing high body mass