Impact of Donor Sex on Graft Outcome in Deceased Donor Kidney Transplantation

Background: Clinically relevant differences between human sexes have been made apparent in many diseases, but studies in kidney transplantation have been producing varying results. Because of recent insight in the possibly fundamental differences between grafts donated after brain death (DBD) and after circulatory death (DCD), we postulated that it is important to look at the effects of donor and recipient sex for donor types individually. Methods: We requested data from the national renal replacement registry of the Netherlands and the Scientific Registry of Transplant Recipients (SRTR, United States). We used cumulative incidence competing risk (CICR) analyses treating recipient death as competing event, and confounder-adjusted cause-specific cox-regression analyses to determine the association of donor sex and donor-recipient sex matching with death-censored graft loss (DCGL) in DBD and DCD. Results: In the Dutch cohort (2010-2024), there were 988 female DBD and 848 male DBD donors, CICR showed that DCGL was more common in grafts from female donors than in male donors (Figure A). Cerebrovascular accident was more common in female donors and donor age was higher than in male donors. After covariate adjustment, the adjusted hazard ratio (aHR) for female DBD donors was 1.43 (95% CI: 1.08–1.88; reference male DBD donors, p=0.013). This association was independent of recipient sex and weight mismatching. There were no differences in DCGL between the grafts from 1031 female and 1619 male DCD donors (Figure B). In a preliminary external validation of these findings in data from the SRTR (DBD N = 112,873, DCD N = 38,289), female donor sex also had a differential impact on DCGL in DBD and DCD. Driving factors explaining these between-sex differences will be analyzed in both cohorts together with kidney biopsy data. Conclusion: Donor sex has a differential impact on outcome specific to donor type. Funding: Commercial Support - Health Holland B.V.Incidence of death-censored graft loss with competing risk recipient death.