Proximity to city centre and cardiometabolic risk in middle-aged and older Australians: Mediating roles of physically active and sedentary travel

Introduction

Research has demonstrated the relationships between living in peri-urban areas and cardiometabolic risk. However, little is known about what types of travel behaviours are involved in the relationship. We examined the mediating roles of multiple measures of active and sedentary travel in the association between the residential proximity to the city centre and cardiometabolic risk among mid-to-older aged Australians.

Methods

Data were from 2259 adults living in and around major Australian cities. The network distance from participants’ residences to the nearest city centre was assessed. A clustered cardiometabolic risk (CCR) score was constructed based on five biomarkers. Four metrics for walking for transport (active travel) and car use (sedentary travel) were measured: weekly frequency, any use of the mode, any use without the other mode, and the use for commuting. Multilevel regression models examined the associations between residential proximity to the city centre and mediators (α) and between mediators and CCR (β). The joint-significance tests identified mediation.

Results

Living farther away from the city centre was associated with a higher CCR score: each 10 km increment in the distance was associated with 0.03 (95%CI: 0.00, 0.05) higher CCR score. The association was partially mediated by walking for transport and car use without walking, for which coefficients α and β were both statistically significant.

Conclusion

Residents of peri-urban areas were at higher cardiometabolic risk than those of inner urban areas, partly due to the former's car-dependent lifestyles. Public health and transport initiatives/policies encouraging walking for transport and discouraging car use in peri-urban suburbs may help to reduce cardiometabolic risk.