Beyond Annual Averages: Rethinking Metrics For Emergency Department Crowding And Capacity Planning

Background Emergency department (ED) crowding compromises patient safety and care efficiency. Most EDs assess crowding using the Annual Average (AA) occupancy method as a baseline due to its simplicity. However, AA’s long-term averaging fails to capture short-term fluctuations, leading to inaccurate capacity estimates. Objectives This study compares six methods for estimating ED bed needs, focusing on evaluating Hourly Peak Bed Occupancy (HPBO) as a practical and accurate alternative to AA. Methods We analyzed data from the National Emergency Department Information System (NEDIS) database, including 408 EDs in South Korea and 7,678,743 hospitalizations in 2022. We used the Real-Time Occupancy (RTO) method, which defines bed shortage as occupancy exceeding 100% for more than 20% of the time, as the gold standard benchmark for comparison. Five other methods—AA, Monthly Average (MA), Daily Average (DA), Daily Peak Bed Occupancy (DPBO), and HPBO—were compared for estimating additional bed needs. Results Of the 408 EDs, 37 (9.1%) had a bed shortage based on the RTO method. For these EDs, the HPBO method estimated a median of 9 beds (IQR 5–16), closely aligning with the RTO estimate of 7 beds (IQR 3–14). In contrast, the AA method underestimated shortages in 7 EDs, with a median estimate of 7 beds (IQR 1–14). Conclusions HPBO overcomes the limitations of AA by capturing short-term occupancy fluctuations, providing accurate estimates of additional bed needs. This offers healthcare administrators a reliable tool for addressing ED overcrowding and optimizing resource allocation.