Living Environmental Quality and Incident Cardiometabolic Multimorbidity: A Prospective Cohort Study in China

Background Cardiometabolic multimorbidity (CMM) imposes a substantial burden on aging populations. While single environmental exposures are known risk factors, the joint effect of multidimensional living environments remains unclear. This study aimed to construct a comprehensive Living Environmental Quality (LEQ) index and investigate its association with incident CMM in China. Methods We included 6,330 adults aged 45 years or older without CMM at baseline from the China Health and Retirement Longitudinal Study (CHARLS). A composite LEQ index (range 0–6) was constructed using housing type, indoor temperature suitability, tap water source, household energy fuel type, and outdoor PM _2.5 exposureto reflect the multidimensional aspects of living environments, and further categorized into high-, medium-, and low-risk groups. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for incident CMM. Extensive sensitivity analyses were conducted, including excluding individuals with baseline hypertension and removing PM₂.₅ from the LEQ index, to assess the robustness of the non-air-quality factors. Results Over a median follow - up of 7 years, 426 participants developed incident CMM. In the fully adjusted model, compared with the high - risk group, the medium - risk group had a 22% reduction in CMM risk (HR: 0.78, 95% CI: 0.64–0.95, P  = 0.016), and the low - risk group had a 48% reduction (HR: 0.52, 95% CI: 0.37–0.72, P  = 0.001). Multi-storey building (HR: 0.75, 95% CI: 0.65–0.87, P  < 0.001) and tap water source (HR: 0.79, 95% CI: 0.69–0.90, P  < 0.001) significantly reduced incident CMM risk. Extensive sensitivity analyses were conducted, including excluding individuals with baseline hypertension and removing PM₂.₅ from the LEQ index, to assess the robustness of the non-air-quality factors. Conclusion Better residential environmental quality was independently associated with a lower risk of incident CMM among middle-aged and older Chinese adults in China. These findings support the potential importance of housing and basic household infrastructure in strategies for CMM prevention.