Emergency department overcrowding, mortality and the 4-hour rule in Western Australia.

OBJECTIVE To assess whether emergency department (ED) overcrowding was reduced after the introduction of the 4-hour rule in Western Australia and whether any changes in overcrowding were associated with significant changes in patient mortality rates. DESIGN, SETTING AND PATIENTS Quasi-experimental intervention study using dependent pretest and post-test samples. Hospital and patient data were obtained for three tertiary hospitals and three secondary hospitals in Perth, WA, for 2007-08 to 2010-11. MAIN OUTCOME MEASURES Mortality rates; overcrowding rates. RESULTS No change was shown in mortality from 2007-08 to 2010-11 for the secondary hospitals and from 2007-08 to 2009-10 for the tertiary hospitals. ED overcrowding (as measured by 8-hour access block) at the tertiary hospitals improved dramatically, falling from above 40% in July 2009 to around 10% by early 2011, and presentations increased by 10%, while the mortality rate fell significantly (by 13%; 95% CI, 7%-18%; P < 0.001) from 1.12% to 0.98% between 2009-10 and 2010-11. Monthly mortality rates decreased significantly in two of the three tertiary hospitals concurrently with decreased access block and an increased proportion of patients admitted in under 4 hours. CONCLUSION Introduction of the 4-hour rule in WA led to a reversal of overcrowding in three tertiary hospital EDs that coincided with a significant fall in the overall mortality rate in tertiary hospital data combined and in two of the three individual hospitals. No reduction in adjusted mortality rates was shown in three secondary hospitals where the improvement in overcrowding was minimal.