Significant increase of emergency department visits for heat-related emergency conditions in the United States from 2008 – 2019: a comprehensive nationwide study

Introduction Exposure to high temperatures is detrimental to human health. As climate change is expected to increase the frequency of extreme heat events, as well as raise ambient temperatures, an investigation into the burden of heat-related emergency department visits is necessary to assess the human health impact of this growing public health crisis. Methods Emergency department visits were sourced from the Healthcare Cost and Utilization Project Nationwide Emergency Department Sample. This dataset collects emergency department visit information from 989 facilities that represent a 20-percent stratified sample of United States hospital-owned emergency departments. Visits were included in this study if the medical diagnosis contained an ICD-9-CM or ICD-10-CM code specific to heat-related emergency conditions. Weighted heat-related emergency department visit counts were generated to estimate the total counts for heat-related emergency department visits across the United States. Visit year and month, hospital geographic region, patient age, and sex were recorded. Incidence rates per 100,000 US population, visit counts, and visit count percent change were analyzed on both a national scale and stratified by month, region, age, and sex. Results A total of 1,007,134 weighted heat-related emergency department visits between 2008 - 2019 were included in this study. The annual incidence rate per 100,000 US population increased by an average of 5.73% (95% CI: 8.64% – 20.1%) per year across the study period, rising from 20.56 in 2008 to 30.41 in 2019. For the twelve-year period, the burden of heat-related emergency department visits was greatest in the South (51.41%). Most cases occurred in July (29.56%), with visits increasing to the greatest degree in July (19.25%, 95% CI: 20.75% – 59.26%) and March (14.36%, 95% CI: 19.53% – 48.25%). Conclusions This study found a significant increase in emergency department visits for heat-related emergency conditions across the United States from the years 2008 to 2019.