Urban densification over 9 years and change in the metabolic syndrome: A nationwide investigation from the ORISCAV-LUX cohort study.

A growing body of evidence suggests that urban densification may be protective against obesity, type 2 diabetes, and cardiometabolic diseases, yet studies on how built environmental features relate to metabolic syndrome (MetS) and its components are scarce. This longitudinal study examines the associations of baseline urban density and densification over 9 years with MetS and MetS components, among 510 participants enrolled in both waves of the ORISCAV-LUX study (2007-2017) in Luxembourg. A continuous MetS score (siMS) was calculated for each participant. Six features of residential built environments were computed around participants' home address: street connectivity, population density, density of amenities, street network distance to the nearest bus station, density of public transport stations, and land use mix. A composite index of urban densification (UDI) was calculated by averaging the six standardized built environment variables. Using adjusted generalized estimating equation (GEE) models, one-SD increase in UDI was associated with a worsening of the siMS score (β = 0.07, 95% CI: 0.02, 0.13), higher triglyceride levels (β = 0.05, 95% CI: 0.02, 0.09), and lower HDL-c levels (β = -1.29, 95% CI: -2.20, -0.38). The detrimental effect of UDI on lipid levels was significant only for participants living in dense areas at baseline. Higher baseline UDI, as well as increased UDI over time among movers, were also associated with greater waist circumference. There were no associations between UDI, fasting plasma glucose and systolic blood pressure. Sex and neighborhood socio-economic status did not moderate the associations between UDI and the cardiometabolic outcomes. Overall, we found limited evidence for an effect of urban densification on MetS and its components. Understanding urban dynamics remains a challenge, and more research investigating the independent and joint health effect of built environment features is needed to support urban planning and design that promote cardiometabolic health.