Ambient heat exposure and hospital admissions for urolithiasis in Brazil: A nationwide ecological study, 2014–2025

Objective: To examine associations between ambient heat exposure, heat extremes and the publicly funded hospital burden of urolithiasis in Brazil. Materials and methods: We conducted a nationwide ecological study of federative unit-months from 2014 to 2025. Admissions were extracted from Brazil’s public hospital system, and ERA5-Land temperature was spatially averaged within each of the 27 federative units. Heat metrics included monthly mean temperature, local 90th/95th percentile heat days and heat-day sequences. Negative binomial models used population offsets and federative unit, month and year fixed effects. Results: The dataset included 3888 observations and 1,144,429 admissions. Annual admission rates increased from 36.1 to 71.2 per 100,000. Each 1°C higher monthly mean temperature was associated with increased admissions (incidence rate ratio 1.03, 95% confidence interval 1.02–1.03). Associations were also observed for five additional days above the 95th percentile (1.04, 1.02–1.05) and in heat sequences (1.03, 1.02–1.04). Conclusion: Ambient heat exposure and daily heat extremes were associated with modest increases in publicly funded hospital admissions for urolithiasis. At the national scale, these findings may inform climate-sensitive surveillance and service planning. Level of evidence: 2c.