Performance of N-terminal-pro-B-type natriuretic peptide in critically ill patients: a prospective observational cohort study

INTRODUCTION The purpose of this study was to assess the accuracy of N-terminal-pro-B-type natriuretic peptide (NT-proBNP) as a diagnostic tool to recognize acute respiratory failure of cardiac origin in an unselected cohort of critically ill patients. METHODS We conducted a prospective observational study of medical ICU patients. NT-proBNP was measured at ICU admission, and diagnosis of cardiac dysfunction relied on the patient's clinical presentation and echocardiography. RESULTS Of the 198 patients included in this study, 102 (51.5%) had evidence of cardiac dysfunction. Median NT-proBNP concentrations were 5,720 ng/L (1,430 to 15,698) and 854 ng/L (190 to 3,560) in patients with and without cardiac dysfunction, respectively (P < 0.0001). In addition, NT-proBNP concentrations were correlated with age (rho = 0.43, P < 0.0001) and inversely correlated with creatinine clearance (rho = -0.58, P < 0.0001). When evaluating the performance of NT-proBNP concentrations to detect cardiac dysfunction, the area under the receiver operating characteristic (ROC) curve was 0.76 (95% confidence interval (CI) 0.69 to 0.83). In addition, a stepwise logistic regression model revealed that NT-proBNP (odds ratio (OR) = 1.01 per 100 ng/L, 95% CI 1.002 to 1.02), electrocardiogram modifications (OR = 11.03, 95% CI 5.19 to 23.41), and severity assessed by organ system failure score (OR = 1.63 per point, 95% CI 1.17 to 2.41) adequately predicted cardiac dysfunction. The area under the ROC curve of this model was 0.83 (95% CI 0.77 to 0.90). CONCLUSIONS NT-proBNP measured at ICU admission might represent a useful marker to exclude cardiac dysfunction in critically ill patients.