NPPB and acute kidney injury: In acute HF, plasma cystatin-C modestly predicted AKI [area under the receiver operating characteristic curve (AUC-ROC) 0.68] and all-cause death or HF hospitalization (AUC-ROC, 95% confidence interval: 0.73, 0.66–0.80) (23, 24), providing prognostic value in addition to N-terminal prohormone of brain natriuretic peptide (NT-proBNP) and troponin (25).