The Association of High Ambient Temperatures and Kidney Disease: A Kidney Disease Surveillance System Ecological...

Short-term heat exposure has been linked with increased risks of AKI and CKD, but the effect on the incidence or prevalence of CKD is unknown. This study examines the association of high temperatures with CKD prevalence and ESKD incidence at county level in the United States (US). County-level diagnosed CKD prevalence data (2005-2019) among Medicare enrollees aged ≥65 years from the US Kidney Disease Surveillance System and ESKD incidence data (2010-2019) from the United States Renal Data System were analyzed. County-specific heat exposure measurements included annual average temperature (AAT) and annual heat wave days from nClimGrid-Daily dataset (US National Centers for Environmental Information). We used a linear mixed model to assess associations between heat exposure and diagnosed CKD prevalence as well as ESKD incidence, while geographically weighted regression assessed spatial variations, adjusting for time-trend, county-specific factors and demographics. Stratified analysis compared associations across socioeconomic subgroups. AAT had significantly positive associations with diagnosed CKD prevalence and ESKD incidence. Each 1°C increase in AAT was associated with a 0.23 (95% confidence interval, 0.20 to 0.27) percentage point increase in the prevalence of diagnosed CKD. Similarly, each 1°C increase in AAT was associated with an additional 1.37 (95% confidence interval, 1.08 to 1.65) ESKD cases/100,000 population. Heat wave days were positively associated with both kidney outcomes, and the strength of these associations increased with higher temperature thresholds and longer duration. Stronger associations between heat exposure and both kidney outcomes were observed in high poverty and nonmetropolitan counties ( P < 0.05). The strength of associations was greater in counties in southern and northwestern regions. The associations between ambient temperature and kidney health, with socioeconomic and regional differences, may have implications for interventions aimed at reducing the potential effects of high temperatures on kidney health, particularly in vulnerable populations.