Increase in patient mortality at 10 days associated with emergency department overcrowding

To quantify any relationship between emergency department (ED) overcrowding and 10-day patient mortality. DESIGN AND SETTING: Retrospective stratified cohort analysis of three 48-week periods in a tertiary mixed ED in 2002-2004. Mean "occupancy" (a measure of overcrowding based on number of patients receiving treatment) was calculated for 8-hour shifts and for 12-week periods. The shifts of each type in the highest quartile of occupancy were classified as overcrowded.

All presentations of patients (except those arriving by interstate ambulance) during "overcrowded" (OC) shifts and during an equivalent number of "not overcrowded" (NOC) shifts (same shift, weekday and period). MAIN OUTCOME MEASURE: In-hospital death of a patient recorded within 10 days of the most recent ED presentation.