Performance of urinary NGAL and L-FABP in predicting acute kidney injury and subsequent renal recovery: a cohort study based on major surgeries.

Background: Acute kidney injury (AKI) is a frequent complication of major surgery. The current study evaluated the power of two biomarkers [urinary neutrophil gelatinase-associated lipocalin (NGAL) and liver-type fatty acid binding protein (L-FABP)] to detect the occurrence of AKI and to predict the recovery from renal dysfunction in a major surgery cohort.

Methods: In this prospective study, 199 patients undergoing major surgery were enrolled. Urinary samples collected from participants before surgery, and 0, 4, and 12 h and 1, 2, 7, and 14 days after surgery were tested for NGAL and L-FABP.

Results: Thirty-seven (18.6%) subjects developed AKI. Urinary NGAL and L-FABP were significantly increased from the time surgery was completed (p<0.05). The peak levels of NGAL and L-FABP occurred 12 and 4 h postoperatively (16.4- and 172.0-fold compared to baseline) in AKI group, respectively. The area under the receiver operating characteristic (ROC) curve (AUC) in NGAL (at 12 h), L-FABP (at 4 h), the most predictive model (NGAL at 12 h+L-FABP at 4 h), and the best combination at the same time point (12 h) was 0.83 [95% confidence interval (CI), 0.74-0.91], 0.85 (95% CI 0.77-0.93), 0.94 (95% CI 0.89-0.98), and 0.91 (95% CI 0.85-0.97), respectively. However, the largest AUC of single and combined biomarkers for predicting non-recovery after AKI only reached 0.70.

Conclusions: Urinary NGAL and L-FABP can be used to detect AKI and combining NGAL and L-FABP may improve the diagnostic performance; however, NGAL and L-FABP may be poor predictors for renal recovery after AKI.