Impact of Donor Age on Graft Failure After Deceased Donor Liver Transplantation by Donor-Recipient Sex Combinations: An Analysis of the UNOS OPTN Database.

Background Sex disparity has been highlighted in personalized medicine for various human diseases including acute/chronic liver diseases. In the transplant community, greater graft failure risk in female-to-male liver transplantation (LT) has been repeatedly reported, and a recent study in living donor LT reported that the inferiority of female-to-male LT is shown only when donor age is ≤40 y. We aimed to analyze the United Network for Organ Sharing (UNOS) database to test if the poorer outcome of female-to-male LT changes by donor age of 40 y in deceased donor LT, as shown in living donor LT. Methods In this retrospective cohort study, 11,752 adult patients in the UNOS registry who underwent deceased donor LT between 2000-2023 were analyzed. Multivariable analysis was performed to adjust the effects from transplant years, graft ischemia time, disease severity, and others. The primary outcome was graft failure. Results Within the subgroup of recipients with ≤40 y donors, graft failure risk was significantly greater in female-to-male LT than others (vs. female-to-female, HR = 1.43 [1.16-1.76], p < 0.001; vs. male-to-female, HR = 1.46 [1.18-1.81], p < 0.001; vs. male-to-male, HR = 1.26 [1.16-1.49], p = 0.009). In contrast, within the subgroup of recipients with >40 y donors, the risk was comparable between female-to-male LT and other donor-recipient sex groups (vs. female-to-female, p = 0.907; vs. male-to-female, p = 0.781; vs. male-to-male, p = 0.937). We tested various cutoff donor ages and determined that 40 y is the best cutoff value to define the risk subgroup in female-to-male LT. Conclusions In the current study, we found that the sex disparity shown in living donor LT is also observed in deceased donor LT. That is, post-transplant graft failure risk was greater in female-to-male LT than other donor-recipient sex groups only when donor age was ≤40 y. In contrast, graft failure risk was comparable irrespective of donor-recipient sex combinations when donor age was >40 y.