Residential greenness associated with lower serum uric acid levels and hyperuricemia prevalence in a large Chinese rural population.

Background: The association between residential greenness and hyperuricemia remains unclear, especially in developing countries. The current study aimed to explore the associations between residential greenness and both serum uric acid (SUA) levels and hyperuricemia in a Chinese rural population and to examine potential pathways of these associations.

Methods: In this cross-sectional study, 38,721 rural residents were recruited from the baseline survey of the Henan Rural Cohort study in 2015-2017. Two satellite-derived vegetation indices, i.e., the normalized difference vegetation index (NDVI) and the enhanced vegetation index (EVI), were used to estimate residential greenness. Air pollution was determined by two proxies: particulate matter with aerodynamic diameter ≤ 2.5 μm (PM) and nitrogen dioxide (NO). Hyperuricemia was defined as SUA levels of >417 μmol/L and > 357 μmol/L for men and women, respectively. Multivariable-adjusted linear regression and logistic regression models were applied to investigate the associations of greenness with SUA and hyperuricemia, and mediation analyses were used to explore possible mechanisms underlying the associations.

Results: An interquartile range (IQR) increase in both EVI and NDVI in the 500 m buffer was significantly associated with reductions in SUA levels of -7.23 μmol/L (95% confidence interval (CI): -8.96, -5.50) and -4.38 μmol/L (95% CI: -5.93, -2.83), respectively. The same increases in EVI and NDVI were associated with 13.8% (95% CI: 5.8%, 21.2%) and 13.0% (95% CI: 5.6%, 19.8%) lower hyperuricemia prevalence, respectively. These associations were stronger in older people (age ≥ 65), men or participants with higher averaged monthly income. The associations were partly mediated by physical activity and BMI, while no mediation effect was observed for air pollution.

Conclusions: Higher levels of residential greenness were significantly associated with lower SUA levels and hyperuricemia prevalence in the Chinese rural population. BMI and physical activity may play important mediating roles in the associations.