Prediction of heart failure mortality in emergent care: a cohort study

Abstract

Background: Heart failure contributes to millions of emergency department (ED) visits, but hospitalization-versus-discharge decisions are often not accompanied by prognostic risk quantification.

Objective: To derive and validate a model for acute heart failure mortality applicable in the ED.

Design: Clinical data abstraction with development of a broadly applicable multivariate risk index for 7-day death using initial vital signs, clinical and presentation features, and readily available laboratory tests.

Setting: Multicenter study of 86 hospitals in Ontario, Canada.

Patients: Population-based random sample of 12 591 patients presenting to the ED from 2004 to 2007.

Measurements: Death within 7 days of presentation.

Results: In the derivation cohort (n = 7433; mean age, 75.4 years [SD, 11.4]; 51.5% men), mortality risk increased with higher triage heart rate (adjusted odds ratio [OR], 1.15 [95% CI, 1.03 to 1.30] per 10 beats/min) and creatinine concentration (OR, 1.35 [CI, 1.14 to 1.60] per 1 mg/dL [88.4 µmol/L]), and lower triage systolic blood pressure (OR, 1.52 [CI, 1.31 to 1.77] per 20 mm Hg) and initial oxygen saturation (OR, 1.16 [CI, 1.01 to 1.33] per 5%). Nonnormal serum troponin levels (OR, 2.75 [CI, 1.86 to 4.07]) were associated with increased mortality risk. Areas under the receiver-operating characteristic curves of the multivariate model were 0.805 for the derivation data set (bootstrap-corrected, 0.811) and 0.826 for validation data set (n = 5158; mean age, 75.7 years [SD, 11.4]; 51.6% men). In the derivation cohort, a multivariate index score stratified 7-day mortality with rates of 0.3%, 0.3%, 0.7%, and 1.9% in quintiles 1 to 4, respectively. Mortality rates in the 2 highest risk groups were 3.5% and 8.2% in deciles 9 and 10, respectively.

Limitation: Left ventricular ejection fraction was not included in the model.

Conclusion: A multivariate index comprising routinely collected variables stratified mortality risk with high discrimination in a broad group of patients with acute heart failure presenting to the ED.

Primary funding source: Canadian Institutes of Health Research.