Emergency department (ED) crowding is associated with adverse outcomes. Several jurisdictions have established benchmarks and targets for length-of-stay (LOS) to reduce crowding. An evaluation has been conducted on whether performance on Ontario’s ED LOS benchmarks is associated with reduced risk of death or hospitalization.

A retrospective cohort study of discharged ED patients was conducted using population-based administrative data from Ontario (April 2008 to February 2012). For each ED visit, the proportion of patients seen during the same shift that met ED LOS benchmarks was determined. Performance was categorized as <80%, 80% to <90%, 90% to <95%, and 95%–100% of same-shift ED patients meeting the benchmark. Logistic regression models analysed the association between performance on ED LOS benchmarks and 7-day death or hospitalization, controlled for patient and ED characteristics and stratified by patient acuity.

From 122 EDs, 2,295,256 high-acuity and 1,626,629 low-acuity visits resulting in discharge were included. Deaths and hospitalizations within 7 days totalled 1,429 (0.062%) and 49,771 (2.2%) among high-acuity, and 220 (0.014%) and 9,005 (0.55%) among low-acuity patients, respectively. Adverse outcomes generally increased among patients seen during shifts when a lower proportion of ED patients met ED LOS benchmarks. The adjusted odds ratios (and 95% confidence intervals) among high- and low-acuity patients seen on shifts when <80% met ED benchmarks (compared with ≥95%) were, respectively, 1.32 (1.05–1.67) and 1.84 (1.21–2.81) for death, and 1.13 (1.08–1.17) and 1.40 (1.31–1.49) for hospitalization.

Better performance on Ontario’s ED LOS benchmarks for each shift is associated with a 10%–45% relative reduction in the odds of death or admission 7 days after ED discharge.