Amino-terminal pro-brain natriuretic peptide as a predictor of outcome in patients admitted to intensive care. A prospective observational study

CONTEXT: Amino-terminal pro-brain-type natriuretic peptide is known to predict outcome in patients with heart failure, but its role in an intensive care setting is not yet fully established. OBJECTIVE: To assess the incidence of elevated amino-terminal pro-brain natriuretic peptide (NT-pro-BNP) on admission to intensive care and its relation to death in the ICU and within 30 days. DESIGN: Prospective, observational cohort study. SETTING: A mixed non-cardiothoracic tertiary ICU in Sweden. PATIENTS AND MAIN OUTCOME MEASURES: NT-pro-BNP was collected from 481 consecutive patients on admission to intensive care, in addition to data on patient characteristics and outcome. A receiver-operating characteristic curve was used to identify a discriminatory level of significance, a stepwise logistic regression analysis to correct for other clinical factors and a Kaplan-Meier analysis to assess survival. The correlation between Simplified Acute Physiology Score (SAPS) 3, Sequential Organ Failure Assessment score (SOFA) and NT-pro-BNP was analysed using Spearman's correlation test. Quartiles of NT-pro-BNP elevation were compared for baseline data and outcome using a logistic regression model. RESULTS: An NT-pro-BNP more than 1380 ng -l on admission was an independent predictor of death in the ICU and within 30 days [odds ratio (OR) 2.6; 95% confidence interval (CI), 1.5 to 4.4] and was present in 44% of patients. Thirty-three percent of patients with NT-pro-BNP more than 1380 ng -1, and 14.6% of patients below that threshold died within 30 days (log rank P=0.005). NT-pro-BNP correlated moderately with SAPS 3 and with SOFA on admission (Spearman's ρ 0.5552 and 0.5129, respectively). In quartiles of NT-pro-BNP elevation on admission, severity of illness and mortality increased significantly (30-day mortality 36.1%; OR 3.9; 95% CI, 2.0 to 7.3 in the quartile with the highest values, vs. 12.8% in the lowest quartile). CONCLUSION: We conclude that NT-pro-BNP is commonly elevated on admission to intensive care, that it increases with severity of illness and that it is an independent predictor of mortality.