Age-specific vulnerability of kidney diseases to temperature: a nationwide case-crossover study.

BACKGROUND: Extreme temperatures are projected to increase; however, comprehensive mapping of associations between temperature extremes and kidney diseases across age groups and disease subtypes remains limited. METHODS: Data were collected for all emergency department (ED) visits for kidney diseases across all ages from South Korea's national health insurance claims between 2011 and 2019. A time-stratified case-crossover design was used to assess the association between ambient temperature and ED visits for kidney diseases. RESULTS: The study included around 1.9 million ED visits due to kidney diseases. Heat-related risks of kidney disease-related ED visits (99th vs. 75th percentile) were highest among adults aged 50-59 years [odds ratio (OR): 1.28, 95% confidence interval (CI): 1.22-1.34), while cold-related risks (1st vs. 25th percentile) were highest among those aged 30-39 years (OR: 1.13, 95% CI: 1.05-1.20). Heat-related hospitalization risk was primarily driven by urinary tract infection among individuals in their 30s (OR: 1.37; 95% CI: 1.09-1.72) and by acute kidney injury among those in their 40s (OR: 2.29; 95% CI: 1.52-3.44). From a cost-burden perspective, urinary tract infections among adults aged ≥70 years contributed the largest medical cost burden attributable to high and low temperatures. CONCLUSIONS: This nationwide study demonstrated age- and disease subtype-specific heterogeneity in temperature-related kidney disease risks. Our findings suggest that, in addition to older adults, younger and middle-aged populations should also be primarily considered in climate change adaptation strategies targeting kidney health.