The Impact of Emergency Department Census on the Decision to Admit

We evaluate recent trends in emergency department (ED) crowding and its potential causes by analyzing ED occupancy, a proxy measure for ED crowding. We analyzed data from the annual National Hospital Ambulatory Medical Care Surveys from 2001 to 2008. The surveys abstract patient records from a national sample of hospital EDs to generate nationally representative estimates of visits. We used time of ED arrival and length of ED visit to calculate mean and hourly ED occupancy. During the 8-year study period, the number of ED visits increased by 1.9% per year (95% confidence interval 1.2% to 2.5%), a rate 60% faster than population growth. Mean occupancy increased even more rapidly, at 3.1% per year (95% confidence interval 2.3% to 3.8%), or 27% during the 8 study years. Among potential factors associated with crowding, the use of advanced imaging increased most, by 140%. But advanced imaging had a smaller effect on the occupancy trend than other more common throughput factors, such as the use of intravenous fluids and blood tests, the performance of any clinical procedure, and the mention of 2 or more medications. Of patient characteristics, Medicare payer status and the age group 45 to 64 years accounted for small disproportionate increases in occupancy. Despite repeated calls for action, ED crowding is getting worse. Sociodemographic changes account for some of the increase, but practice intensity is the principal factor driving increasing occupancy levels. Although hospital admission generated longer ED stays than any other factor, it did not influence the steep trend in occupancy. Copyright © 2012. Published by Mosby, Inc.

We examine the validity of the emergency department (ED) occupancy rate as a measure of crowding by comparing it to the Emergency Department Work Index Score (EDWIN), a previously validated scale. A multicenter validation study was conducted according to ED visit data from 6 academic EDs for a 3-month period in 2005. Hourly ED occupancy rate (ie, total number of patients in ED divided by total number of licensed beds) and EDWIN scores were calculated. The correlation between the scales was determined and their validity evaluated by their ability to discriminate between hours when 1 or more patients left without being seen and hours when the ED was on ambulance diversion, using area under the curve (AUC) statistics estimated from the bootstrap method. We calculated the ED occupancy rate and EDWIN for 2,208 consecutive hours at each of the 6 EDs. The overall correlation between the 2 scales was 0.58 (95% confidence interval [CI] 0.56 to 0.60). The ED occupancy rate (AUC=0.73; 95% CI 0.65 to 0.80) and the EDWIN (AUC=0.65; 95% CI 0.58 to 0.72) did not differ significantly in correctly identifying hours when patients left without being seen. The ED occupancy rate (AUC=0.78; 95% CI 0.75 to 0.80) and the EDWIN (AUC=0.70; 95% CI 0.59 to 0.81) performed similarly for ED diversion hours. The ED occupancy rate and the EDWIN classified leaving without being seen and ambulance diversion hours with moderate accuracy. Although the ED occupancy rate is not ideal, its simplicity makes real-time assessment of crowding feasible for more EDs nationwide.