Donor-recipient Sex Differences Do Not Affect Survival Outcomes After Kidney Transplantation: A Population Cohort Study

Background. Donor factors can influence decision making for organ utilization for potential kidney transplant candidates. Prior studies exploring the effect of donor-recipient sex matching on kidney transplant outcomes have reported heterogenous and conflicting results. The aim of this contemporary population-cohort analysis was to explore the effect of donor-recipient sex matching on kidney transplant outcomes in the United Kingdom. Methods. In this retrospective, observational study, we analyzed all patients receiving kidney-alone transplants between 2003 and 2018 using UK Transplant Registry data. Stratified by recipient sex, outcomes were compared between male and female donors with univariable/multivariable analyses. Results. Data were analyzed for 25 140 recipients. Of these, 13 414 (53.4%) of kidneys were from male donors and 15 690 (62.4%) of recipients were male. The odds of initial graft dysfunction (delayed graft function/primary nonfunction) were significantly lower for female donor kidneys transplanted into both male (adjusted odds ratio = 0.89, 95% confidence interval [CI] = 0.80-0.98, P = 0.019) and female (adjusted odds ratio = 0.81, 95% CI = 0.71-0.93, P = 0.003) recipients. Male recipients of female donor kidneys had creatinine levels at 1 year that were 6.3% higher (95% CI = 4.8%-7.7%, P < 0.001) than male recipients of male donor kidneys, with a similar sex difference of 4.1% (95% CI = 2.1%-6.1%, P < 0.001) observed within female recipients. However, neither patient nor graft survival was found to differ significantly by donor sex on either univariable or multivariable analysis. Conclusions. Our data provide contemporary data on sex mismatch for recipient counseling and reassurance with regards to equivalent long-term clinical outcomes based upon donor sex.