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

Abstract

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.