Different Severity of Clinical Outcomes Between the 2 Subgroups of Stage 1 Acute Kidney Injury After Liver Transplantation.

Background. Although the Kidney Disease: Improving Global Outcomes (KDIGO) criteria is used to define acute kidney injury (AKI) after liver transplantation, the criteria was criticized for including 2 heterogeneous groups of different serum creatinine (sCr) criteria together in AKI stage 1. We investigated whether there are significant differences in clinical outcomes between 2 subgroups of patients within AKI stage 1. Methods. A total of 1440 cases were reviewed. The AKI stage 1 (n = 443) were divided into 2 subgroups based on changes in sCr level (stage 1a: >= 0.3 mg/dL of absolute sCr increase, n = 251; stage 1b: >= 50% relative sCr increase, n = 192). Propensity score analysis was performed between stage 1a and 1b groups, yielding 157 matched pairs. We compared the length of hospital stay, early allograft dysfunction, and 5-year all-cause mortality between these subgroups after matching. Kaplan-Meier analyses were performed to compare the graft or overall survival between the subgroups after matching. Sensitivity analysis for Acute Kidney Injury Network (AKIN) criteria was performed. Results. Length of hospital stay and 5-year all-cause mortality was significantly worse in patients with stage 1b compared to stage 1a after matching. Five-year graft or patient survival was significantly worse in patients with stage 1b compared to stage 1a after matching (Log-rank test P = 0.022 and P = 0.027, respectively). These results were the same regarding AKIN criteria. Conclusions. The KDIGO criteria for AKI stage 1 could be further divided into 2 substages with different severity of clinical outcomes. This modified criteria could give additional prognostic information in patients undergoing liver transplantation.