Comparison of neutrophil gelatinase-associated lipocalin versus B-type natriuretic peptide and cystatin C to predict early acute kidney injury and outcome in patients with acute heart failure

Neutrophil gelatinase-associated lipocalin (NGAL) has been described in chronic heart failure (HF) as marker of tubular damage and renal dysfunction; however, less data are available in patients with acute HF. Because of high rate of acute kidney injury (AKI) development, we aimed to investigate the role of NGAL in predicting early AKI development; second, we compared NGAL with respect to cystatin C, B-type natriuretic peptide (BNP), renal function, and blood urea nitrogen (BUN) for outcome prediction. We measured admission serum NGAL, cystatin C, and BNP in 231 patients affected to acute HF; all patients were submitted to daily creatinine, estimated glomerular filtration rate, and measurement to identify inhospital AKI defined by Risk, Injury, Failure, Loss, End-Stage Kidney Disease and Acute Kidney Injury Network criteria. We also measured admission and discharge estimated glomerular filtration rate, creatinine, and BUN to evaluate their prognostic role during a 6-month follow-up period; 78 patients developed AKI during hospitalization. In these subjects, NGAL levels were significantly increased respect to patients without AKI (295 ± 228 vs 129 ± 108 ng/ml, p <0.001). A cutoff of 134 ng/ml has been related to AKI with good sensibility and specificity (85% and 80%, respectively; area under the curve 0.81, p <0.001). BNP was also mildly increased (1,000 ± 906 vs 746 ± 580 pg/ml, p = 0.03) but not cystatin C. Patients with chronic kidney disease demonstrated higher NGAL levels compared with subjects with preserved renal function (258 ± 249 and 120 ± 77 ng/ml, p <0.001). The receiver-operating characteristic curve analysis demonstrated that increased NGAL values were associated with increased mortality (cutoff 170 ng/ml, sensibility 60%, specificity 82%, accuracy 71%, area under the curve 0.77, p <0.001). The same significant correlation was also found for BUN at discharge (cutoff 100 mg/dl, sensibility 65%, specificity 85%, accuracy 71%, area under the curve 0.77, p <0.001). Multivariable Cox regression analysis showed that cutoff 170 ng/ml was related with adverse outcome (hazard ratio 1.77, confidence interval 1.24 to 2.83, p = 0.01). In conclusion, NGAL measurement is a sensible tool to predict AKI during hospitalization. Elevated NGAL levels appear to be related to BUN increase and post-discharge outcome. This suggests a prognostic role of tubular damage beyond renal dysfunction.