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 asso-ciated with poor outcomes. We assessed the associations between urinary neutrophil ge-latinase-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 mea-sured 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 all -cause 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 ad-mission 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 concentra-tions 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], respec-tively) 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 combina-tion, was limited. Further studies are required to confirm our results.