Impact of Emergency Department Boarding on Delays in Second-Dose Antibiotic Administration

Emergency department (ED) boarding is the prolonged stay of admitted patients in the ED due to limited inpatient bed availability. ED boarding has been associated with adverse outcomes, including increased in-hospital mortality, delays in care, and medical errors. As such, delays in time-sensitive therapies such as antibiotics are a rising concern. While associations between ED boarding and delayed initial antibiotic administration have been studied, data on its impact on second-dose antibiotic delays are limited.

This single-center retrospective cohort study spanned January 1, 2023 to June 30, 2025. Adult patients were included if they received cefepime or piperacillin/tazobactam in the ED, received at least one subsequent beta-lactam antibiotic dose, and were admitted to the hospital. Patients were stratified by ED boarding duration of <4 hours and >4 hours based on The Joint Commission’s recommendation that ED boarding time not exceed 4 hours. The primary outcome was the frequency of major delays in second-dose antibiotic administration. Secondary outcomes included hospital length of stay, in-hospital mortality, and ICU admission rates. Categorical variables were analyzed using chi-square tests, and continuous variables using two-sample t-tests.

Among 1132 encounters, 614 patients boarded for <4 hours and 518 boarded for >4 hours. Baseline characteristics were largely similar; however, the <4 hour group included a higher proportion of Emergency Severity Index (ESI) 1 patients (27 vs 0, p=<0.005), representing the most critically ill population. Most patients in both groups were triaged as ESI 2 or 3. No significant difference was observed in delays to second-dose antibiotic administration between groups (34% vs 31%; p=0.29). ICU admission rates were higher in the <4 hour group (22% vs 4%; p=<0.005), whereas in-hospital mortality was higher among patients who boarded for >4 hours (3.5% vs 1.3%; p=0.015).

ED boarding duration was not associated with differences in second-dose antibiotic administration delays. However, patients who boarded for >4 hours had lower ICU admission rates, yet higher in-hospital mortality. These findings highlight the complex relationship between ED boarding, patient acuity, and downstream clinical outcomes. Further evaluation of care transitions and antibiotic stewardship during ED boarding is needed.