Background: Climate change has increased the frequency and intensity of periods of extreme heat, which are associated with elevated mortality. Little is known about the association of emergency hospital admissions with particular risk groups.
Methods: We used anonymized data from the statutory health insurance system in Germany (4.3 million persons; 1.48 million emergency hospital admissions) and temperature data (resolution: 9 x 9 km) to estimate the risk of emergency hospitalization as a function of daily mean temperature during the summer months over the period 2017-2022. The time-series analysis that was used also enabled the calculation of temporally delayed and non-linear associations (distributed lag non-linear model). We conducted subgroup analyses by age, sex, and diagnostic group to identify vulnerable groups.
Results: Our study showed that the risk of emergency hospitalization increased with increasing temperatures. For daily mean temperatures above 17°C, we estimated an additional 7002 emergency admissions over the 6-year study period, with a cumulative overall risk of 1.03 (95% confidence interval: [1.01; 1.04]) compared to days with a mean temperature of 17°C. On days with extreme heat (mean daily temperature, 25°C), the relative risk (RR) of emergency hospitalization was increased for children (RR: 1.06 [1.01; 1.11]) and persons over age 65 (RR: 1.03 [1.01; 1.05]). As for diagnostic groups, the relative risk for emergency hospitalization associated with days of extreme heat was higher among persons with endocrine, nutritional, and metabolic diseases (1.63 [1.50; 1.78]), diseases of the skin and subcutaneous tissue (1.18 [1.07; 1.32]), genitourinary diseases (1.13 [1.03; 1.24]), respiratory diseases (1.09 [1.02; 1.17]), and injuries, poisoning, and other consequences of external causes (1.05 [1.02; 1.09]).
Conclusion: The overall effect of heat on the risk of emergency hospitalization was small, yet in some cases considerable for children, persons aged 65 and older, and certain diagnostic groups. This indicates a need for targeted preventive measures.