Microsteatosis may not interact with macrosteatosis in living donor liver transplantation

Background & Aims The insignificance of pure microsteatosis (MiS) was reported in living donor liver transplantation (LDLT). However, since steatosis is mostly found in a mixed form of microsteatosis (MiS) and macrosteatosis (MaS), we aimed to determine the importance of MiS mixed with MaS in LDLT. Methods Donor matching and recipient matching were independently performed with unfixed matching ratios. In donor matching, 51 donors with high (≥30%) MiS mixed with MaS (H-MiS) were matched with 160 donors with low (≤10%) MiS mixed with MaS (L-MiS), based on MaS degree, remnant liver volume, and others. In recipient matching, 50 recipients who received H-MiS grafts were matched with 176 recipients who received L-MiS grafts, based on MaS degree, graft volume, MELD score, and others. Results The median MiS degree was 10% (range 0%-10%) vs. 35% (range 30%-80%) in L-MiS livers vs. H-MiS livers after both matching. L-MiS and H-MiS donors were not significantly different regarding postoperative biochemical liver function (e.g. peak AST 232 vs. 246 IU/L, p = 0.931). L-MiS and H-MiS recipients were not significantly different regarding 2-week graft regeneration (51% for both) and 5-year survival (HR 0.87, 95% CI 0.43-1.76, p = 0.699). Post-transplant donor/recipient complication rates were not significantly different, either. Conclusions There were no evidences of a significant impact of MiS mixed with MaS on post-LDLT outcomes. The results suggest less importance of MiS, and further indicate that there is no interaction between MiS and MaS. Thus, the risk of steatosis may be determined by the relative composition of MiS and MaS, rather than the total quantitative degree.