Association between flood exposure and chronic kidney disease: A nationwide cross-sectional study in China.

Flooding has become more frequent and intense due to climate change, yet its long-term health impacts, especially on chronic kidney disease (CKD), remain underexplored. This study examines the association between long-term flood exposure and CKD among adults in China using data from 47,204 participants in a nationally representative survey. Flood exposure was defined as satellite-detected inundation occurring within 10 km of participants' residences during the one to seven years preceding the survey. CKD was defined by an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m2 and/or the presence of albuminuria. Generalized additive models were used to estimate odds ratios (ORs) and 95 % confidence intervals (CIs), adjusting for sociodemographic and lifestyle factors. Flood exposure significantly increased the odds of CKD at a one-year lag (OR 1.87, 95 % CI 1.67-2.11), and this effect persisted up to seven years post-event (OR 1.12, 95 % CI 1.00-1.25). Albuminuria showed the strongest association with flood exposure at the one-year lag (OR 2.25, 95 % CI 1.98-2.56), subsequently declining, whereas reduced eGFR (<60 mL/min/1.73 m2) became significantly associated from three years onward, peaking at five years post-flood (OR 2.20, 95 % CI 1.75-2.75). Subgroup analyses indicated that rural residents, lower-income individuals, and females were particularly vulnerable within the first year following flooding. These findings suggest that flood exposure has long-term adverse impacts on CKD, particularly among certain vulnerable populations. Further research is needed to explore the underlying mechanisms of this relationship.