Emergency department crowding and outcomes after emergency department discharge

Gelareh Z. Gabayan, Stephen F. Derose, Vicki Y. Chiu, Sau C. Yiu, Catherine A. Sarkisian, Jason P. Jones, Benjamin C. Sun

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Study objective We assess whether a panel of emergency department (ED) crowding measures, including 2 reported by the Centers for Medicare & Medicaid Services (CMS), is associated with inpatient admission and death within 7 days of ED discharge. Methods We conducted a retrospective cohort study of ED discharges, using data from an integrated health system for 2008 to 2010. We assessed patient transit-level (n=3) and ED system-level (n=6) measures of crowding, using multivariable logistic regression models. The outcome measures were inpatient admission or death within 7 days of ED discharge. We defined a clinically important association by assessing the relative risk ratio and 95% confidence interval (CI) difference and also compared risks at the 99th percentile and median value of each measure. Results The study cohort contained a total of 625,096 visits to 12 EDs. There were 16,957 (2.7%) admissions and 328 (0.05%) deaths within 7 days. Only 2 measures, both of which were patient transit measures, were associated with the outcome. Compared with a median evaluation time of 2.2 hours, the evaluation time of 10.8 hours (99th percentile) was associated with a relative risk of 3.9 (95% CI 3.7 to 4.1) of an admission. Compared with a median ED length of stay (a CMS measure) of 2.8 hours, the 99th percentile ED length of stay of 11.6 hours was associated with a relative risk of 3.5 (95% CI 3.3 to 3.7) of admission. No system measure of ED crowding was associated with outcomes. Conclusion Our findings suggest that ED length of stay is a proxy for unmeasured differences in case mix and challenge the validity of the CMS metric as a safety measure for discharged patients.

Original languageEnglish (US)
Pages (from-to)483-492.e5
JournalAnnals of emergency medicine
Issue number5
StatePublished - Nov 2015
Externally publishedYes

ASJC Scopus subject areas

  • Emergency Medicine


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