Extreme heat and risk of pediatric emergency department visits: a time-stratified time-series analysis.

BACKGROUND: Children are vulnerable to heat, yet evidence on heat-related pediatric emergency department (ED) use in Germany remains limited. We quantified the acute short-term effects of extreme heat exposure on ED visits among children aged 0-18 years in Baden-Württemberg, Germany. METHODOLOGY: We assessed short-term effects of extreme heat on ED visits among children aged 0-18 years, including perinatal conditions in infants born at or after 22 weeks´ gestation, in Baden-Württemberg, Germany using 2.83 million records from (2014-2022). A time-stratified quasi-Poisson design with distributed lag non-linear model (lag 0-5 days) was applied, adjusting for air quality, spatiotemporal factors, and COVID-19 hospitalizations. RESULTS: Higher temperatures increased ED visits risk, strongest within 0-2 days. Cumulative relative risks increased by 4.2% (95% CI 3.7-4.8), 7.1% (6.1-8.1), and 9.6% (8.2-11.1) at the 95th, 99th, and 99.9th temperature percentiles, respectively. Heat-sensitive diagnoses included heat-related illnesses (+63%, 51-76), perinatal conditions (+57%, 26-92), and otitis media and externa (+25%, 16-33). Children < 5 years had higher ED visit rates share on hot days (RR 1.036, 1.02-1.05). CONCLUSION: Heat exposure increases pediatric ED use, highlighting the need of child-specific thresholds and targeted preparedness strategies. IMPACT: Extreme heat increases pediatric emergency visits, especially among infants and young children. By combining high resolution meteorological data with a large pediatric dataset and advanced time stratified modeling, the study provides detailed evidence on short-term effects of heat and identifies specific heat sensitive diagnoses. The study highlights rapid, lagged effects of heat and suggests pediatric specific temperature thresholds that may better capture risk than current heat warning thresholds. The findings support improving preparedness in pediatric emergency care and inform adaptations to heat warning-systems to better cater for child populations.