Long-term exposure to residential greenness and cardiovascular disease and all-cause mortality in China

Influence of residential greenness on CVD risk has garnered increasing attention, however, evidence from large-scale cohort studies in developing nations, such as China, remains sparse. This study aimed to evaluate the association of residential greenness with CVD and mortality, and explore the potential mediating role of modifiable risk factors in the associations. A total of 22,702 participants aged 35 years and above were enrolled between October 2012 and December 2015. Residential greenness was assessed using Normalized Difference Vegetation Index (NDVI) within radii of 300 m, 500 m, and 1000 m from participants' residential address (NDVI300 m, NDVI500 m, and NDVI1000 m). Primary outcomes comprised CVD events and all-cause mortality, with follow-up from 2018 to 2019. Multivariable Cox regression models were employed to estimate hazard ratios (HRs), and causal mediation analysis was conducted to assess the role of modifiable risk factors in the observed associations. Residential greenness demonstrated a significant association with the risk of CVD, with HRs per tertile increment of 0.84 (95% confidential interval [CI]: 0.77–0.92) for NDVI300 m, 0.86 (95% CI: 0.79–0.94) for NDVI500 m, and 0.90 (95% CI: 0.82–0.98) for NDVI1000 m, separately. Compared to areas with the lowest NDVI500 m, the HR for CVD incidence in areas with medium and high NDVI500 m were 0.89 (95% CI: 0.76–1.06), and 0.74 (95% CI: 0.62–0.89), respectively. Utilizing a newly proposed two-stage regression method in mediation analysis, approximately 16.18%, 5.34%, 4.04%, and 2.45% of the total effect of NDVI500 m on CVD risk were mediated by high-density lipoprotein cholesterol, physical activity, body mass index, and diabetes mellitus, respectively. This study provides compelling evidence that higher residential greenness is associated with a reduced risk of CVD among the adult Chinese population, with specific modifiable risk factors playing a mediating role. These findings underscore the significance of incorporating green space interventions into CVD prevention strategies.