Characteristics of ED crowding in the Lazio Region (Italy) and short-term health outcomes.

The effect of emergency department (ED) crowding on patient care has been studied for several years in the scientific literature. We evaluate the association between ED crowding and short-term mortality and hospitalization in the Lazio region (Italy) using two different measures. A cohort of visits in the Lazio region ED during 2012-2014 was enrolled. Only discharged patients were selected. ED crowding was estimated using two measures, length of stay (LOS), and Emergency Department volume (EDV). LOS was defined as the interval of time from entrance to discharge; EDV was defined at the time of each new entrance in ED. The outcomes under study were mortality and hospitalization within 7 days from ED discharge. A multivariate logistic model was performed (Odds Ratios, ORs, 95% CI). The cohort includes 2,344,572 visits. ED crowding is associated with an increased risk of short-term hospitalization using both LOS and EDV as exposures (LOS 1-2 h: OR = 1.71, 95% CI 1.66-1.76, LOS 2-5 h: OR = 1.38, 95% CI 1.34-1.43, LOS > 5 h OR = 1.45 95% CI 1.40-1.50 compared to patients with 1 h of LOS; EDV 75°-95° percentile: OR = 1.02, 95% CI 0.99-1.05 and EDV > 95° percentile: OR = 1.06, 95% CI 1.01-1.11 compared to patients with a EDV < 75° percentile upon arrival). Increased risk of short-term mortality is found with increasing level of LOS. High levels of EDV at the time of patients' arrival and longer LOS in ED are associated with greater risks of hospitalization for patients discharged 7 days before. LOS in ED is also associated with an increased risk of mortality.