MO950: Living Donor Kidney Transplantation—Does Donor Sex Modify Recipient Outcomes?
Authors: Ventura Sofia , Cruz Gonçalo , Sousa Círia , Figueiredo Cátia , Silvano José , Pedroso Sofia , Almeida Manuela , Malheiro Jorge , Salete Martins La , Cabrita António 
Published: May 2022

Abstract

BACKGROUND AND AIMS
Living donor kidney transplantation (LDKT) provides the best outcomes of all renal replacement modalities, including survival and quality of life. Studies on the association between pre-donation estimated glomerular filtration rate (eGFR) and graft outcomes have yielded inconsistent results. Two eGFR thresholds are generally used to accept or deny a donor (respectively, ≥90 and &lt;60 mL/min/1.73 m2), with 60–89 mL/min/1.73 m2 as an intermediate range in which the decision is based on other factors. In this study, we aimed to evaluate how donor's pre-donation eGFR, particularly when &lt;90 mL/min/1.73 m2 impacts the recipient's kidney function and graft survival, and if these outcomes are modified by donor's sex.

METHOD
This is a unicentric retrospective observational study that included the LDKT pairs submitted to transplant between 2008 and 2017. We gathered clinical data, including donor's comorbidities, immunological features of the transplant, the occurrence of acute rejection episodes in the first year, and graft eGFR during the follow-up period.
For statistical purposes, we split the donors in three groups: group 1, with eGFR ≥90 mL/min/1.73 m2; group 2, eGFR &lt; 90mL/min/1.73 m2 and female sex; and group 3, eGFR &lt;90 mL/min/1.73 m2 and male sex. The Kaplan–Meier curves and Cox proportional hazards multivariable regression were used for survival analysis, and linear mixed regression was used to evaluate the annual slope of the recipient's eGFR.

RESULTS
We studied 210 donor-recipient pairs. The average age at the time of transplant was 48.0 ± 10.6 years for donors and 41.3 ± 13.3 years for recipients. Pre-donation eGFR was 100.1 ± 14.2 mL/min/1.73 m2 and most donors (78%) were in group 1 (eGFR 105.9 ± 9.4 mL/min/1.73 m2).
We found two independent predictors of death censored graft failure: the occurrence of rejection episode(s) during the first year (HR: 4.99, CI: 1.44–17.26, P = 0.011) and having a donor from group 3 (HR: 5.14, CI: 1.49–17.75, P &lt; 0.010). The independent predictors of global graft loss were rejection episode(s) during the first year (HR: 4.002, CI: 1.224–13.086, P = 0.022), calculated PRA &gt; 0% (HR: 3.802, CI: 1.387–10.489, P = 0.010) and donor from group 3 (HR: 3.514, CI: 1.087–11.355, P = 0.036).
At 1-year after transplant, the recipients from group 1 had a significantly higher eGFR than patients from group 2, but did not differ from group 3 (respectively, 60.8 versus 54.4 [P &lt; 0.05], versus 55.2 mL/min/1.73 m2 [P = 0.328]). However, when analyzing the slope of annual decline in the recipients’ eGFR beyond 1-year post-transplant, the groups 1 and 2 did not differ (decline rate of -1.0 mL/min/1.73 m2 in both groups, P = 0.978), but there was a statistical difference between groups 1 and 3 (decline rates of, respectively, −1.0 versus −2.7 mL/min/1.73 m2 P = 0.003).

CONCLUSION
This study suggests that in LDKT, when donors’ eGFR is borderline (&lt;90 mL/min/1.73 m2), donors’ sex has an important impact on recipient outcomes. In fact, we observed that having a male donor is a strong predictor of graft failure (both death-censored and global) and that there is a steeper decline in the annual kidney function of these recipients after the first year. Thus, we suggest that donors’ eGFR should be clinically balanced with other determinants of kidney function, particularly in the presence of a male donor, with careful selection of both donors and recipients.