Predictors of patient length of stay in 9 emergency departments.

OBJECTIVES: Prolonged emergency department (ED) length of stay (LOS) is linked to adverse outcomes, decreased patient satisfaction, and ED crowding. This multicenter study identified factors associated with increased LOS.

METHODS: This retrospective study included 9 EDs from across the United States. Emergency department daily operational metrics were collected from calendar year 2009. A multivariable linear population average model was used with log-transformed LOS as the dependent variable to identify which ED operational variables are predictors of LOS for ED discharged, admitted, and overall ED patient categories.

RESULTS: Annual ED census ranged from 43,000 to 101,000 patients. The number of ED treatment beds ranged from 27 to 95. Median overall LOS for all sites was 5.4 hours. Daily percentage of admitted patients was found to be a significant predictor of discharged and admitted patient LOS. Higher daily percentage of discharged and eloped patients, more hours on ambulance diversion, and weekday (vs weekend) of patient presentation were significantly associated with prolonged LOS for discharged and admitted patients (P < .05). For each percentage of increase in discharged patients, there was a 1% associated decrease in overall LOS, whereas each percentage of increase in eloped patients was associated with a 1.2% increase in LOS.

CONCLUSIONS: Length of stay was increased on days with higher percentage daily admissions, higher elopements, higher periods of ambulance diversion, and during weekdays, whereas LOS was decreased on days with higher numbers of discharges and weekends. This is the first study to demonstrate this association across a broad group of hospitals.