Impact of renal disease on natriuretic peptide testing for diagnosing decompensated heart failure and predicting mortality.

BACKGROUND: Concomitant occurrence of kidney disease (KD) and heart failure (HF) is common and associated with poor outcomes. Natriuretic peptide studies have typically excluded many individuals with KD. We compared the accuracy of B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) for diagnosing decompensated HF and predicting mortality across the spectrum of renal function.
METHODS: BNP and NT-proBNP were prospectively measured in a cohort of 831 dyspnea patients. KD was defined as an estimated glomerular filtration rate <60 mL . min(-1) . (1.73 m(2))(-1). The accuracy and predictive value of each test for diagnosing decompensated HF and predicting all-cause 1-year mortality were assessed by ROC area under the curve (AUC) and multivariate regression analysis.
RESULTS: Among the 831 dyspnea patients, 393 (47%) had KD. The diagnostic accuracies of BNP and NT-proBNP in detecting decompensated HF were similar to each other in patients without KD (AUC 0.75 vs 0.74, respectively; P = 0.60) and in patients with KD (AUC 0.68 vs 0.66; P = 0.10). One-year mortality rates were 36.3% and 19.0% in those with and without KD, respectively (P <0.001). Progressively higher BNP and NT-proBNP concentrations remained predictive of increased mortality in KD patients. Compared with the lowest quartile, quartile 4 of BNP had an adjusted hazards ratio (HR) of 2.6 (95% CI 1.4-4.8; P = 0.004 for trend) and NT-proBNP quartile 4 had an HR of 4.5 (95% CI 2.0-10.2; P <0.001 for trend). Only NT-proBNP remained a predictor of death after adjustment for clinical confounders and the other natriuretic peptide marker.
CONCLUSIONS: NT-proBNP and BNP are equivalent predictors of decompensated HF across a spectrum of renal function, but NT-proBNP is a superior predictor of mortality.