Background: Heatstroke is a life-threatening condition representing the most severe manifestation of heat-related illnesses. It is characterized clinically by extremely elevated body temperature, neurologic dysfunction, and multiorgan failure. Unmitigated fossil fuel use is increasing global average temperatures, which may impact the incidence of heatstroke admissions. Vulnerability to heat-related illness varies within communities based on exposure characteristics, adaptive capacity, and sensitivity. This study sought to better characterize regional trends in heatstroke admissions in the U.S., specifically comparing the Northeast and South due to their significant monthly temperature differentials.
Methods: This retrospective cohort study used the National Inpatient Sample database. Regional comparisons were made between the Northeast and South (as defined by the U.S. Census Bureau) for the years 2016-2020. Multiple logistic and linear regression techniques were used to study in-hospital clinical (mortality) and resource utilization (length of stay and total hospital charges) outcomes. In addition, monthly temperature information was secured from the National Centers for Environmental Information. Multiple linear regression with a linear spline was used to evaluate the relation between monthly average temperature and monthly admissions.
Results: Across the five years, more heatstroke admissions occurred in the South (n = 9,465) compared to Northeast (n = 1,900). Compared to the Northeast, patients admitted with heatstroke in the South were more likely to be younger, male, non-white, uninsured and admitted at a rural hospital (p < 0.01 for all variables). Seasonal trends were observed in both regions such that the proportion of heatstroke admissions was 5.2 and 7.6 times higher in June, July, and August compared to any other non-overlapping three-month period for the South and Northeast, respectively. Admission rates were positively associated with increasing average monthly temperatures even after controlling for region and season (p < 0.05). Patients admitted with heatstroke in the South and Northeast regions had similar lengths of stay (3.0 vs. 2.8 days, p=0.07), mean charge per case ($38,982 vs. $32,400, p=0.09), and in-hospital mortality rates (1.7% vs. 1.0%, p=0.51). However, more patients in the South were discharged to home compared to the Northeast (77.7% vs 66.5%, p=0.04).
Conclusions: Heatstroke is a serious condition, and admissions to our nation’s hospitals are likely to continue to increase as our planet gets warmer. Many societal, physiologic, and geographic variables impact vulnerability to heat-related illness. Our society and healthcare systems must actively work towards improving resilience to heat-related illness, with a particular focus on the vulnerable patients who may require extra-attentive care to improve outcomes.