Association of urban built environment and socioeconomic factors with suicide mortality in high-density cities: A case study of Hong Kong.

Population ageing, climate change and urbanization have been occurring rapidly globally. Evidence-based healthy city development is required to improve living quality and mitigate the adverse impact of city living on both physical and mental health. We took a high-density city as an example to explore the association of built environment and suicide mortality and preferably to offer some implications for better future city development. Poisson generalized linear models with generalized estimation equations were employed to regress suicide mortality rate on four urban built environment variables (frontal area density (FAD), sky view factor (SVF), ground coverage ratio (GCR), and street coverage ratio (SCR)), as well as socioeconomic factors, population density, and greenery. The association for different causes of death and within different subgroups was also investigated. Generally, higher FAD and GCR were associated with higher suicide mortality while higher SVF and SCR were associated with lower suicide mortality. Age was a significant effect modifier. An interquartile range increase in FAD, SVF, and GCR was associated with 0.81 (95% confidence interval (CI) 0.71-0.92), 1.41 (95% CI 1.04-1.91), and 0.70 (95% CI 0.50-0.98) times the risk of suicide among the people aged over 70, respectively. Higher population density and unmarried status were generally associated with higher suicide rate whereas higher education level was associated with a decreased risk. Unfavorable built environment could increase risks for successful suicide attempts. Better urban development with morphological control mitigating intensifying urban heat island and other micro-environment changes are warranted to promote not only physical but psychological health.