In previous research, studies have documented significant links between length of stay (LOS) over 24-hour periods and hospital occupancy, the number of ED admissions, and other factors. In the May 2012 Western Journal of Emergency Medicine, my colleagues and I published a study that looked at LOS in more discreet time periods than what earlier analyses have reported. We did this because ED crowding and volume can vary greatly during a given 24-hour period. We wanted to find out which factors were associated with LOS and whether this relationship was present during all or only specific 8-hour shifts.
In our analysis, independent variables were measured during three 8-hour shifts. Shift 1 was from 7:00 am to 3:00 pm, shift 2 was from 3:00 pm to 11:00 pm, and shift 3 was from 11:00 pm to 7:00 am. For each shift, the numbers of ED nurses on duty, discharges, discharges on the previous shift, resuscitation cases, admissions and ICU admissions, and LOS on the previous shift, were measured. For each 24- hour period, the numbers of elective surgical admissions and hospital occupancy were measured, since these could not be measured in 8-hour time intervals.
ED Length of Stay: Roles of Occupancy & Admissions
On all three shifts, LOS increased by about 1 minute for each additional 1% increase in hospital occupancy. The mean hospital occupancy in our study was 94.9%; considering this high level of demand for inpatient beds, even a 1% increase in occupancy can lead to significant delays. The demand for inpatient beds often exceeds 100% capacity during the late morning and early afternoon hours on weekdays. To alleviate this burden, inpatients destined for home or transfer to another institution should be discharged from the ED early.
For each additional admission from the ED, LOS increased by 3 to 5 minutes on all shifts examined in the study. The number of patients ultimately admitted to the ICU from the ED was an important subset of all ED admissions and increased LOS for all ED patients. LOS increased by more than 14 minutes when three or more patients were admitted to the ICU on shift 1. This finding suggests that administrative redesign may improve our ability to decide on admitting patients to the ICU. For example, disease-specific protocols may allow for some patients to be cared for in a step-down or telemetry unit more appropriately than in an ICU.
It should be noted that the numbers of resuscitation cases, elective surgical admissions, and nurses were not independently associated with LOS in our study. This most likely was the result of these measures being overshadowed by the greater effects of hospital occupancy and the number of ED admissions as a whole, including ICU admissions in particular.
More Research Needed on Length of Stay
While our study provides helpful insights, future studies are needed to assess how reducing variability and LOS can affect patient outcomes and medical errors. As answers emerge, we hope that more interventions can be developed to reduce the problems associated with ED crowding.
Readings & Resources (click to view)
Rathlev NK, Obendorfer D, White LF, et al. Time series analysis of emergency department length of stay per 8-hour shift. West J Emerg Med. 2012;13:163-168. Available at: http://escholarship.org/uc/item/86m0t8pq or http://www.medscape.com/viewarticle/767437.
Rathlev NK, Chessare J, Olshaker J, et al. Time series analysis of variables associated with daily mean emergency department length of stay. Ann Emerg Med. 2007;49:265-271.
Chan TC, Killeen JP, Vilke GM, et al. Effect of mandated nurse-patient ratios on patient wait time and care time in the emergency department. Acad Emerg Med. 2010;17:545-552.
Forster AJ, Stiell IG, Wells G, et al. The effect of hospital occupancy on emergency department length of stay and patient disposition. Acad Emerg Med. 2003;10:127-133.
Lucas R, Farley H, Twanmoh J, et al. Emergency department flow: the influence of hospital census variables on emergency department length of stay. Acad Emerg Med. 2009;16:597-602.
Chan L, Reilly KM, Salluzzo RF. Variables that affect patient throughput times in an academic emergency department. Am J Med Qual. 1997;12:183-186.