Emergency Department Overcrowding Despite Lower Post-Pandemic Volumes: A Multicenter Study

Background: The COVID-19 pandemic profoundly affected emergency department (ED) activity worldwide, and health system constraints may persist beyond the pandemic phase. Methods: This multicenter retrospective study included all ED visits by patients aged ≥14 years at four Italian tertiary EDs in 2019 and 2024. Input, throughput, and output measures were compared using negative binomial regression and Weibull accelerated failure time models. Results: Overall, 286,298 visits occurred in 2024 and 310,900 in 2019 (adjusted change, -5.5%; 95% CI -9.8 to -1.0). The reduction mainly involved low-priority and daytime presentations. Despite lower input, flow metrics and crowding worsened. Door-to-physician time increased from 51 to 58 min (+21.6%; 95% CI 20.9 to 22.4). Median ED occupancy increased by 8.0% (95% CI 4.5 to 11.6), and the number of patients who left without being seen (LWBS) increased by 17.1% (95% CI 12.9 to 21.5). Total ED LOS increased from 3 h 48 min to 4 h 27 min (+15.1%; 95% CI 14.4 to 15.7). The number of admitted patients with an ED LOS of ≥12 h increased by 13.8% (95% CI 10.3 to 17.3), while ED LOS among admitted patients increased from 13 h 17 min to 19 h 21 min (+29.0%; 95% CI 27.3 to 30.8). ED LOS increased most for admissions to medical wards but decreased for critical care admissions. Conclusions: In 2024, ED volumes were lower than in 2019, whereas ED occupancy, LWBS, and ED LOS were higher, with substantial heterogeneity across centers. These findings suggest a role for hospital output constraints, but the descriptive design does not establish causality.