Prediction of in-hospital mortality by brain natriuretic peptide levels and other independent variables in acutely ill patients with suspected heart disease.
BACKGROUND: Brain natriuretic peptide (BNP) measurement can detect and assess heart failure. However, compared with traditional clinical parameters, its value for predicting the in-hospital mortality of patients with suspected heart disease has not been reported. STUDY DESIGN: Examination of the ability of 11 continuous and 22 categorical variables, including BNP levels measured at the time of admission, was conducted to predict in-hospital mortality. SETTING: A small, rural Irish hospital. SUBJECTS: Six hundred forty-two consecutive patients with suspected heart disease admitted as acute medical emergencies. RESULTS: Thirty-eight (5.9%) patients died while in hospital. They had significantly higher BNP levels on admission than did patients subsequently discharged alive (763+/-473 pg/mL versus 368+/-412 pg/mL, P<0.0001). Patients who died in hospital were older; had significantly higher white blood cell counts, blood urea, respiratory rates and modified early warning scores; and had significantly lower blood pressure and hemoglobin levels. Five variables were found to be independent predictors of mortality: a systolic blood pressure of 90 mmHg or less; a hemoglobin level of 100 g/L or less; a white blood cell count greater than 13.0 x 10(9)/L being unwell before the current illness; and a BNP level of 700 pg/mL or greater. The presence of three or more of these variables was associated with an in-hospital mortality rate of 39%. CONCLUSIONS: Five independent variables (hypotension, anemia, leukocytosis, prior illness and elevated BNP levels) are comparable predictors of in-hospital mortality in patients with suspected heart disease.