Objectives: The influence of donor-recipient sex mismatches on long-term graft survival after liver transplant is controversial. In this study, our aim was to characterize the differences in long-term graft outcome after liver transplant in more than 2000 cases with special regard to sex match and mismatch. Materials and Methods: In this retrospective, single center study of 2144 adult primary liver transplant recipients (median follow-up of 92 months), we analyzed specific long-term graft survival and the effect of different donor and recipient sex combinations (KaplanMeier, multivariate regression). Results: In the 15-year follow-up, female recipients (58.6%) had significantly better graft survival than male recipients did (51.6%, P = .031). Matched and mismatched male-female combinations revealed significant differences (P = .003): a male donor-female recipient combination showed the best 15-year graft survival (61.1%), and a female donor-male recipient combination showed the worst graft survival (48.6%), whereas male-male (53.3%) and female-female combinations (55.6%) were not significantly different (P = .967). Donor age (P < .0001), body mass index (P = .021), female sex (P = .015), Eurotransplant Donor Risk Index > 1.4 (P < .001), recipients' age (P < .0001), indication for liver transplant (P < .0001), and kidney function (P = .003) significantly affected graft survival. In the multivariate analysis model, a Eurotransplant Donor Risk Index > 1.4 and impaired kidney function at liver transplant again emerged as significant negative predictors. Female donors and male recipients showed significantly more unfavorable characteristics concerning long-term graft survival.
Conclusions:The impressive long-term graft survival benefit of male donor-female recipient versus female donor-male recipient and of male donor-female recipient versus matched groups (male-male, femalefemale) in liver transplant may be caused by significant differences in donor quality and recipient charac teristics and may not be related to sex itself.