Predictive Performance of Neutrophil Gelatinase Associated Lipocalin, Liver Type Fatty Acid Binding Protein, and Cystatin C for Acute Kidney Injury and Mortality in Severely Ill Patients

BACKGROUND: Acute kidney injury (AKI) is a common condition in severely ill patients associated with poor outcomes. We assessed the associations between urinary neutrophil gelatinase-associated lipocalin (uNGAL), urinary liver-type fatty acid-binding protein (uLFABP), and urinary cystatin C (uCysC) concentrations and patient outcomes. METHODS: We assessed the predictive performances of uNGAL, uLFABP, and uCysC measured in the early phase of intensive care unit (ICU) management and at discharge from the ICU in severely ill patients for short- and long-term outcomes. The primary outcome was the occurrence of AKI during ICU stay; secondary outcomes were 28-day and 1-yr allcause mortality. RESULTS: In total, 1,759 patients were admitted to the ICU, and 728 (41.4%) developed AKI. Median (interquartile range, IQR) uNGAL, uLFABP, and uCysC concentrations on admission were 147.6 (39.9–827.7) ng/mL, 32.4 (10.5–96.0) ng/mL, and 0.33 (0.12–2.05) mg/L, respectively. Biomarker concentrations on admission were higher in patients who developed AKI and associated with AKI severity. Three hundred fifty-six (20.3%) and 647 (37.9%) patients had died by 28 days and 1-yr, respectively. Urinary biomarker concentrations at ICU discharge were higher in non-survivors than in survivors. The areas under the ROC curve (95% confidence interval) of uLFABP for the prediction of AKI, 28-day mortality, and 1-yr mortality (0.70 [0.67–0.72], 0.63 [0.59–0.66], and 0.57 [0.51–0.63], respectively) were inferior to those of the other biomarkers. CONCLUSIONS: uNGAL, uLFABP, and uCysC concentrations on admission were associated with poor outcomes. However, their predictive performance, individually and in combination, was limited. Further studies are required to confirm our results.