New advances in the pathophysology of AKI

Introduction and Aims: Neutrophil gelatinase-associated lipocalin (NGAL) is a biomarker of acute kidney injury (AKI). Most NGAL studies have focused on the early diagnosis of AKI using serum creatinine (Cr)- based definitions as the gold standard. However, another potential application is guidance in the decision to initiate renal replacement therapy (RRT) in patients with AKI. The aim of this study was to assess the ability of plasma NGAL to predict the need for RRT in adult critically ill patients with AKI. Methods: We performed a meta-analysis of individual patient data from two prospective ICU cohort studies. AKI was defined as an increase in serum Cr of at least 50% from baseline. Serial plasma NGAL (pNGAL) were measured using a point-of-care standardized clinical platform from ICU admission up to 3rd ICU day in both cohorts. For the analysis, we used Cr and pNGAL on the 1st day of meeting AKI criteria. Primary endpoint of the study was the composite of RRT initiation or death within 7 days of AKI diagnosis. Results: Individual data of 933 adult patients entered the pooled analysis. Of these 284 had AKI during their ICU stay; 272 had both Cr and pNGAL values on the 1st AKI day. Seventy patients developed the primary outcome, 40 had RRT/death more than 7 days after AKI diagnosis, and 162 survived without need of RRT. Their median pNGAL values on the 1st AKI day were 699, 457 and 223 ng/mL, respectively. The area under the receiver operating characteristic curve for the composite of RRT/death within 7 days was 0.70 (95% confidence interval (CI), 0.56-0.85) for pNGAL, 0.67 (95%CI, 0.53-0.82) for Cr and 0.73 (95%CI, 0.59-0.88)