A Single-Center Retrospective Study to Identify Causes of Sex Differences in the Living Kidney Donor Evaluation Process

Key Points Female overrepresentation in living kidney donation stems from higher self-referral rates, not differences in approval or follow-through. Male volunteers are not more likely to be declined as donors due to medical contraindications, contrary to common assumptions. Engaging more male volunteers in living donation could expand access to kidney transplantation and reduce waitlist times. Background Multiple studies have shown that female volunteers are living donors (LDs) for kidney transplantation at higher rates than male volunteers. However, the underlying reasons for this observation are not well understood. We examined the LD evaluation process to determine the point at which sex imbalance arises. On the basis of a previous study, we hypothesized that both sexes are equally likely to become approved as LDs, but female volunteers are more likely to follow through with donation. Methods This is a single-institution retrospective chart review of self-referrals for LD evaluation between January 2009 and December 2022. Self-referrals were identified using the Organ Transplant Tracking Record database and cross-referenced with billing data. Exclusion at each stage of evaluation was recorded and compared between sexes using log binomial regression; unadjusted and adjusted (for donor age, race, ethnicity, relationship to recipient, and recipient sex) risk ratios with 95% confidence interval were determined. Results One thousand eight hundred sixty-one self-referrals were reviewed, including 1214 female (65.2%) and 647 male (34.8%) volunteers, resulting in 146 approvals and 125 donations (76/125, 60.8% female, 49/125, 39.2% male). Adjusted risk ratios indicated no significant differences between sexes in completing medical and/or psychosocial workup, having medical and/or psychosocial contraindications, being approved for donation, and proceeding with donation. The top medical contraindications for both sexes were obesity, hypertension, and nephrolithiasis. Conclusions Female overrepresentation among LDs is likely due to the 1.9 times higher rate of self-referral for evaluation. After this point, both sexes were equally likely to complete workup, be approved, and follow through with donation. Increased efforts to engage male volunteers at the initial self-referral stage has the potential to expand access to LD kidney transplantation. Podcast This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/K360/2024_12_26_KID0000000581.mp3