Combined Effect of Deceased Donor Macrovesicular and Microvesicular Steatosis on Liver Transplantation Outcomes: Analysis of SRTR Data Between 2010 and 2018

Background. Because of the rising prevalence of obesity, the use of steatotic grafts in orthotopic liver transplantation is becoming increasingly obligatory. The purpose of this study was to determine the relative distribution of microvesicular steatosis (MiS) burden across categories of macrovesicular steatosis (MaS) and the effect of biopsy-sourced MaS and MiS on graft failure, recipient death, and retransplantation. Methods. We performed a retrospective analysis of 13,889 adults with deceased donor liver transplantations from the Scientific Registry of Transplant Recipients between 2010 and 2018. Multivariable Cox proportional hazards models were run to examine the independent and combined effects of MaS and MiS on major transplantation outcomes. Results. Recipients had a mean age of 56.5 years and a body mass index (BMI) of 29.2 kg/m(2); 70% were men, and 74% were non-Hispanic white. Considering the independent effect of MaS, recipients of livers with 30% to 60% MaS had 97% and 129%, 71% and 81%, 39% and 43%, and 40% and 19% increased risks of graft failure and death at 1 month, 3 months, 1 year, and 3 years post-transplantation, respectively. Considering the combined effects of MaS and MiS, 16% to 60% MaS increased the risk of graft failure and recipient death regardless of MiS burden within the first 3 months post-transplantation. These risks were also increased among recipients of livers with 5% to 15% MaS and the additional burden of 16% to 60% MiS. Conclusions. Our findings suggest that risk threshold of adverse transplantation outcomes owing to steatosis appears to be lower than previously recognized and currently practiced. These risks must be weighed and mitigated against the duress of organ shortage and saving lives.