Background: Historically, liver allografts with >30% macrosteatosis (MaS) on donor biopsy have been associated with early allograft dysfunction and worse graft survival; however, successful outcomes have been reported in small cohorts. This study proposes an elevated MaS threshold for organ utilization without detriment to graft survival.
Methods: The UNOS Standard Transplant Analysis and Research database was evaluated for transplants between 2006-2015. Graft survival up to 1-year was evaluated by Kaplan-Meier (KM) survival analyses, and by univariate and multivariable logistic regression analyses, including donor and recipient characteristics. Odds ratios (OR) with 95% confidence intervals (CI) for risk of graft loss are reported.
Results: Thirty-day risk of graft loss was increased with MaS as low as 10-19% (OR [95% CI] 1.301 [1.055-1.605], p<0.0001) and peaked with MaS 50-59% (2.921 [1.672-5.103]). At 1-year, risk of graft loss remained elevated with MaS 40-49% (1.465 [1.002-2.142]) and MaS 50-59% (1.978 [1.281-3.056], p = 0.0224). Multivariable models were created for Lower and Higher MELD recipients and MaS cutoffs were established. In Lower MELD recipients, organs with ≥50% MaS had increased risk of graft loss at 30 days (2.451 [1.541-3.897], p = 0.0008) and 1-year post-transplant (1.720 [1.224-2.418], p = 0.0125). Higher MELD recipients had increased risk of graft loss at 30 days with allografts showing MaS ≥40% (4.204 [1.440-5.076], p = 0.0016). At 1-year the risk remained increased, but MaS was not significant predictor of graft loss.048 [1.131-3.710], p = 0.0616). In both MELD cohorts, organs with MaS levels below threshold had similar survival to those transplanted without a donor biopsy.
Conclusions: In conjunction with recipient selection, organs with MaS up to 50% may be safely used without detriment to outcomes.