During the early phase of the coronavirus disease 2019 (COVID-19) outbreak, many emergency departments (EDs) were exposed to COVID-19 and were temporarily closed according to national protocol of Korea. We aimed to evaluate the effect of concurrent and recurrent temporary closures of EDs on the clinical outcomes of patients who visited EDs during the COVID-19 outbreak.

This cross-sectional study used a nationwide emergency patient database. Patients who visited one of the 46 EDs in Daegu and Gyeongbuk between January 21 and April 14, 2020 were included. The main exposure variable was the first medical contact (ED visit or 119 call to emergency medical services (EMS)) during closure of at least one ED. There were 25 temporary closures of six Level-1 and Level-2 EDs between February 18 and March 17, 2020. We constructed a dataset by performing bidirectional crossover matching and conducted a conditional logistic regression analysis where the primary outcome was in-hospital mortality.

Of the 94,360 eligible study participants, 36,327 were classified into the non-EMS-use group and 10,116 were classified into the EMS-use group. In-hospital mortality rates were 2.0% and 1.6% for the temporary-closure and no-closure groups in the non-EMS-use group (p-value, 0.03) and 8.7% and 7.4% in the EMS-use group (p-value, 0.02), respectively. In the conditional logistic analysis for in-hospital mortality, the odds ratios (95% confidence intervals) of the temporary-closure group compared the no-closure group were 1.22 (1.03–1.44) among the non-EMS-use group and 1.23 (1.04–1.46) among the EMS-use group.

The temporary closures of EDs due to the unpredicted COVID-19 exposure resulted in an increase in emergency patients' in-hospital mortality rates irrespective of whether they used EMS. Preparing regional EMS systems to cope with new outbreaks is essential to protect the safety of all citizens.