Emergency department hypotension predicts sudden unexpected in-hospital mortality: a prospective cohort study.

OBJECTIVE The prevalence and prognostic significance of nontraumatic hypotension measured in the emergency department (ED) have not been studied. We hypothesized that ED hypotension confers risk of in-hospital mortality. DESIGN Prospective cohort study. SETTING Large urban ED with 115,000 visits per year. PARTICIPANTS Nontrauma ED patients aged > 17 years admitted to the hospital were prospectively identified on a random sample of 24-h blocks during 2004 to 2005. "Exposures" had any systolic BP (SBP) < 100 mm Hg in the ED; "nonexposures" all had SBP >/= 100 mm Hg in the ED. Deaths were classified as sudden and unexpected by independent observers using explicit criteria. OUTCOME MEASURES Mortality rates were compared with confidence intervals (CIs), Kaplan-Meier survival curves, and multivariate logistic regression. RESULTS A total of 4,790 patients were enrolled during the study period, with 887 patients (19%) in the exposure group. Exposures were more likely to die in the hospital compared with nonexposures (8% vs 3%; 95% CI for difference of 5%, 4 to 8%). Exposures were more likely to have sudden and unexpected death compared with nonexposures (2% vs 0.2%, 95% CI for difference of 1.8%, 1 to 3%). Kaplan-Meier estimates showed increased mortality in the exposure group at all time points (log-rank test, p < 0.001). Multivariate logistic regression revealed exposure to hypotension as an independent predictor of in-hospital mortality (odds ratio, 2.0; 95% CI, 1.3 to 2.8). CONCLUSION Nontraumatic hypotension was documented in 19% of a random sample of ED patients admitted to the hospital. Patients exposed to hypotension had a significantly increased risk of death during hospitalization.