Renal dysfunction and accuracy of N-terminal pro-B-type natriuretic peptide in predicting mortality for hospitalized patients with heart failure.

BACKGROUND: Renal dysfunction may confound the clinical interpretation of N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration. This study investigated whether renal dysfunction influences the prognostic accuracy of NT-proBNP in acute decompensated heart failure (ADHF). METHODS AND RESULTS: We studied 908 ADHF patients. The primary outcome was 12-month mortality. Interaction between estimated glomerular filtration rate (eGFR) and NT-proBNP in predicting mortality was tested with the likelihood ratio test. The patients were classified into 3 eGFR strata: ≥60, 30-59, and <30 ml·min(-1)·1.73 m(-2). Cox models were used to calculate the adjusted hazard ratios (HR) for NT-proBNP, modeled as a dichotomous or categorized variable, within each level of eGFR. NT-proBNP was categorized using optimal cut-offs defined in ROC analysis for each eGFR level. A total of 234 patients (25.8%) died. Testing for interaction was not significant (χ(2)=0.29; P=0.5928). The adjusted HR for NT-proBNP >5,180 pg/ml was 2.09 (P<0.001) in the highest, 1.7 (P<0.001) in the intermediate, and 3.33 (P=0.010) in the lowest eGFR level. The adjusted HR for NT-proBNP above the optimal cut-offs defined on ROC analysis were 1.5 (P=0.239), 2.2 (P<0.001), and 3.24 (P=0.002), respectively. The models incorporating NT-proBNP as a dichotomous or categorized variable had equivalent C-statistics. CONCLUSIONS: There was no evidence of interaction between eGFR and NT-proBNP in predicting mortality. The NT-proBNP cut-off of 5,180 ng/L provided independent prognostic information, irrespective of the level of residual renal function.