Reevaluating Donor-recipient Sex Mismatch and Survival After Liver Transplantation: A Contemporary Cohort Study

Background. Identifying an optimally matched donor is a critical determinant of outcomes following liver transplantation (LT). Several donor- and recipient-related factors have been shown to influence posttransplant survival. However, the impact of donor-recipient sex mismatch (DRSM) on long-term outcomes remains controversial, with inconsistent findings reported across prior studies. This study aimed to further clarify the contemporary role of DRSM in LT outcomes. Methods. We conducted a single-center retrospective cohort study including 1146 adult patients who underwent LT at the Ajmera Transplant Centre, Toronto, between January 2014 and January 2022. Donor and recipient characteristics, including age, sex, and donor type, were analyzed. The primary outcome was patient survival up to 10 y of follow-up. Comparative analyses were performed between recipients with mismatch (DRSM+) and those without (DRSM–), as well as relevant subgroup analyses. Results. In unadjusted survival analysis, recipients in the DRSM+ group demonstrated slightly higher survival compared with DRSM– recipients up to 10 y following LT ( P = 0.018). However, after multivariable adjustment and propensity score matching, survival was comparable between groups, and DRSM was not identified as an independent predictor of mortality. Subgroup analyses showed no adverse effect of DRSM in deceased donor transplantation ( P = 0.547), while a survival difference was observed in the living donor cohort ( P < 0.001). In addition, female recipients exhibited improved survival compared with male recipients, irrespective of DRSM. Conclusions. DRSM does not appear to be an independent risk factor for reduced long-term survival after LT. Moreover, the composition of favorable recipient and donor characteristics seems to be the main factors influencing long-term survival. These findings suggest that DRSM alone should not preclude donor selection in clinical practice.