Impact of heatwave exposure on chronic kidney disease risk among middle-aged and older adults: evidence from the China health and retirement longitudinal study

Chronic kidney disease (CKD) represents a major global public health concern. The increasing morbidity of extreme heat events, attributed to global climate change, may pose a substantial risk to renal health. Nonetheless, the body of evidence examining the relationship between heatwave exposure and CKD remains sparse, especially among middle-aged and older demographic groups. This study employed data from the China Health and Retirement Longitudinal Study, analyzing information from 6,718 participants aged 45 years and older during the follow-up period from 2011 to 2015. Kidney function was evaluated using the estimated glomerular filtration rate (eGFR) at both baseline and endpoint surveys. Heatwaves were characterized by various temperature thresholds (e.g. the 90th,95th, and 97.5th percentiles) and durations of 2 to 4 consecutive days. Logistic regression models were utilized to examine the association between heatwave exposure and the morbidity of CKD, with sensitivity analyses conducted to ensure the robustness of the findings. Our study identified consistent and positive correlations between heatwave exposure and the risk of CKD across various definitions. We observed that higher intensity and prolonged duration of heatwaves were associated with increased odds of developing CKD, suggesting a dose–response relationship. Through clustering analysis, we identified geographic heterogeneity, distinguishing “dual high-risk zones” characterized by both high CKD prevalence and extended heat exposure, and “heatwave-dominant zones” marked by lower CKD prevalence but prolonged heat exposure. Furthermore, under conditions of high-intensity heatwaves, specifically HW11(97.5th percentile for 3 days) and HW11 (97.5th percentile for 4 days), significant interactions were observed among participants with pre-existing chronic conditions such as hypertension, diabetes, and heart disease. Exposure to heatwaves constitutes an independent environmental risk factor for CKD among middle-aged and older adults. These findings underscore the necessity of integrating climate-related risks into strategies for the prevention of chronic kidney disease.