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

Abstract

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.
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.
Prospective, observational cohort study.
A mixed non-cardiothoracic tertiary ICU in Sweden.
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.
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).
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.