High Heat Exposure and Medical Utilization among the Chronic Kidney Disease Population

We investigated the relationship between temperature and healthcare utilization among patients with chronic kidney disease (CKD). We utilized panel regression models with individual and year fixed effects to evaluate how exposure to different levels of temperature (measured by heat index) was associated with changes in weekly healthcare utilization from October 1, 2015, to March 31, 2023. Data were derived from medical claims data, Parameter-Elevation Regressions on Independent Slopes Model (PRISM) climate data, and the Census block group of each individual. The study population was comprised of 916,886 individuals with commercial or Medicare insurance who had been diagnosed with CKD stage G3, G4, or G5. CKD was defined using diagnosis codes in medical claims and estimated glomerular filtration rate (eGFR) laboratory results. Exposure was the number of days in a week with a daily heat index in ten-degree Fahrenheit bins. Results: We found that exposure to a higher heat index bin, 90-100F compared to 60-70F, was associated with an increase in weekly emergency department utilization (0.55%; 95% CI: 0.42%-0.68%; p<0.001), with larger percent increases for ED visits with a heat-related primary diagnosis code (2.07%; 95% CI: 1.63%-2.51%; p<0.001) or a kidney-related primary diagnosis code (1.37%; 95% CI: 0.56%-2.17%; p <0.001). ED visits with a primary diagnosis code related to kidney disease were associated with a larger impact among those least likely to have access to air conditioning (2.48%; 95% CI: 0.84%-4.13%; p<0.01). Smaller, statistically significant results were observed comparing heat indexes of 80-90F to 60-70F. Conclusions: Exposure to heat indexes above 90 degrees was associated with greater weekly ED utilization and ED utilization with heat- or kidney-related primary diagnosis codes. Copyright © 2025 by the American Society of Nephrology...