Heat-related illness trends at a pediatric health care system, 2012-2023.

As extreme summer temperatures become more frequent due to a changing climate, there is an increased risk of heat-related morbidity and mortality, particularly in vulnerable populations such as children. We aimed to examine trends in heat-related illness over time and describe differences in patient characteristics and outcomes for children with "heat-specific" diagnoses compared to rhabdomyolysis, a severe form of heat-related illness. We conducted a retrospective study at a pediatric health care system with two large children's hospitals to identify Emergency Department encounters with a heat-related ED diagnosis from May-September from 2012 to 2023. Aggregate heat-related illness encounters, as a proportion of total ED encounters, increased 170% from 2012 (4.3 per 10,000) to 2023 (11.6 per 10,000) (p=0.01). Summer months with higher peak temperatures had higher heat-related ED volume (R2=0.44, p<0.001). Most heat-specific encounters resulted in ED discharge (96%), while most rhabdomyolysis encounters resulted in admission (63%). We found that ED volume for heat-related illness is associated with higher temperature and is increasing over time. Heat-specific diagnoses are more common than rhabdomyolysis. Given the rise in healthcare utilization from heat-related illness, it is essential for all pediatricians to understand the health implications of our changing climate.