Recipient-Donor Sex Combinations and Posttransplant Infections: A Swiss Transplant Cohort Study

Despite increasing interest in sex and gender in transplant medicine, the impact of recipient-donor sex combinations (RDSCs) on posttransplant infections, graft survival, and rejection remains unclear. To assess if RDSC is independently associated with infectious events in solid organ transplantion (SOT) recipients.

This retrospective cohort study assessed a national prospectively maintained registry including six transplant centers. All adult patients, undergoing primary transplant of either heart, kidney, liver, or lung, between May 1, 2008, and December 31, 2021, were included. Endpoints were clinically significant infectious events (primary endpoint), graft survival, rejection, and overall survival within the first year. Patients were grouped as per RDSC. The primary statistical outcome of the organ-specific, a priori known risk factor-adjusted analyses are reported as incidence rate ratios (IRRs).

The cohort included 5033 recipients: 2886 (57.3%) kidney, 1224 (24.3%) liver, 515 (10.2%) lung, and 408 (8.1%) heart transplants, documenting 6067 infections. Recipient-donor sex mismatch was not associated with weighted posttransplant infection risk in heart (IRR: 1.06; 95% CI: 0.75, 1.48; p = 0.75), kidney (IRR: 1.03; 95% CI: 0.90, 1.17; p = 0.69), liver (IRR: 1.10; 95% CI: 0.81, 1.50; p = 0.52), or lung (IRR: 1.02; 95% CI: 0.82, 1.26; p = 0.89) recipients. Female kidney recipients had significantly higher infection rates than males (IRR: 1.50; 95% CI: 1.32, 1.71; p < 0.001), largely explained by urinary tract infections. One-year graft survival, rejection, and overall survival were unaffected by RDSC across all organs.

RDSC does not influence 1-year SOT infectious outcome, as well as rejection or graft survival as exploratory outcomes.