Abstract & Commentary
Source: Forster AJ, et al. The effect of hospital occupancy on emergency department length of stay and patient disposition. Acad Emerg Med 2003; 10:127-133.
If you are dealing with a packed emergency department (ED) and waiting room, and wondering why all the changes in the function of your department have not produced better throughput, this article is a must-read for you. This was an observational study, using administrative data at a 500-bed acute care teaching hospital. All patients presenting to the ED between April 1993 and June 1999 were included in the study. The predictor variable was daily hospital occupancy. Outcome measures included daily ED length of stay for admitted patients, daily request for admissions by the ED service (or "consultation rate" in this Canadian study), and daily admission rate. The authors employed a technique known as autoregressive, integrated, moving average (ARIMA) modeling to control for covariates. This model controlled for the average daily age of ED patients and the average daily "arrival density" index, which adjusts for patient volume and clustering of patient arrivals. In short, the authors tracked the ED length of stay (LOS) during the seven years that the number of hospital beds were purposely reduced from an average of 610 to 432. The reduction in these beds was as a result of cost-saving measures. During this overall trend, daily and seasonal variations in occupancy also were seen and factored into the study.
The results are fascinating and clearly show that as occupancy (as a percentage of available beds) increases, the LOS in the ED increased. Daily ED LOS for admitted patients increased 18 minutes when there was an absolute increase in occupancy of 10%. The ED LOS appeared to markedly increase when hospital occupancy exceeded a threshold of 90%. The number of requests for admissions and admission rates were not influenced by hospital occupancy. The authors conclude that efforts to increase hospital bed availability may be an important strategy to reducing ED overcrowding. Furthermore, they suggest that temporarily increasing the number of beds once occupancy reaches a threshold of 90% could result in shorter ED LOS.
Commentary by Richard J. Hamilton, MD, ABMT, FAAEM
I have a computer game called "Roller Coaster Tycoon" that allows you to set-up and manage an amusement park. When you play this game in earnest, you immediately acquire a practical understanding of queuing theory. You learn that when a ride has too few seats and the line gets too long, you had better increase capacity or people will walk out. If you build too much capacity into a ride, then it takes a long time to recoup your investment, although people are quite pleased with their experience. This study shows that overall occupancy affects ED LOS. However, according to queuing theory, waiting time may even increase when there is insufficient capacity in only some units — such as telemetry or intensive care. I told a hospital administrator that the ED LOS would improve only when we got more telemetry beds and he told me he wouldn’t build those beds because I would "only fill them up with more patients." After I got up from the floor, I decided I had better understand how queuing theory was affecting my practice. My simple-minded analysis produced the following insights: 1) the cost of care largely is based on the number of nurses staffing beds (capacity); 2) the greatest profit is obtained when the maximum number of patients that those nurses can care for are in the hospital (highest occupancy); and 3) the greater the occupancy rate, the greater the LOS in the ED (longer queuing for care). In order for a hospital to become more profitable, it must either increase capacity (with the same occupancy rate) or increase occupancy (by decreasing capacity). It is infinitely easier, especially in the short term, to cut back on staffed beds than it is to attract new patients and build services. Thus, the net result is higher occupancy, greater profit margin, and prolonged ED LOS. No wonder we’re in trouble!
Why is this important to study? I think that the future of emergency medicine will come into focus when we realize that the ED is overcrowded because the hospital has reached a state of dysfunction, not because we’re not working hard enough or we don’t have enough point-of-care tests to achieve rapid dispositions and turnaround times. Solutions only will come when we change the way we handle capacity and occupancy of beds in-house (e.g., example, by using a flexible unit for short stay admissions such as an observation unit, or by increasing the staffing when occupancy rises — as the authors suggest).
Dr. Hamilton, Associate Professor of Emergency Medicine, Program Director, Emergency Medicine, MCP, Hahnemann University, Philadelphia, PA, is on the Editorial Board of Emergency Medicine Alert.
If you are dealing with a packed emergency department and waiting room, and wondering why all the changes in the function of your department have not produced better throughput, this article is a must-read for you.
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