Impact of donor and recipient sex on graft function among deceased donor kidney recipients: A paired-kidney analysis.

Females improved resilience to ischemia-reperfusion injury has been reported in animal models, a protection largely attributed to sexual hormones. Clinically, the impact of sex on short- and long-term outcomes after kidney transplantation is unclear. In this retrospective cohort study using the United Network for Organ Sharing database, we analyzed paired donor kidneys transplanted to 2 opposite sex adult recipients (N = 39 197 males and N = 39 197 females), thereby controlling for all donor-related covariates. The primary endpoint was delayed graft function. Secondary outcomes included 1-year graft and patient survival and estimated glomerular filtration rate at 6 months and 1 year. We adjusted the results for the following covariates: years receiving dialysis, human leukocyte antigen mismatch, calculated panel reactive antibodies, and cold ischemic time. Consistent with preclinical data, female donor and recipient sex was associated with reduced delayed graft function, especially in the context of donation after cardiocirculatory death (F-to-M: odds ratio [OR] = 0.73, M-to-F: OR = 0.59, F-to-F: OR = 0.39, reference: M-to-M; P < .0001 for all comparisons). Female recipients had improved 1-year graft and patient survival, while male donor sex was associated with improved 1-year estimated glomerular filtration rate, independently of donor size. These findings highlight the role of sex as a clinically relevant biological variable influencing transplant outcomes.