Estimated Glomerular Filtration Rate Less Than 90 mL/min/1.73m² in Living Donor Candidates Under 30 Years Old and Long-Term Outcomes

Background: Traditionally, glomerular filtration rate (GFR) ≥80 mL/min/1.73 m² has been the threshold for living kidney donor (LKDs) acceptance. Recently, the threshold has been lowered for older donors. There is consideration of raising it for younger donors. Methods: We compared long-term outcomes for LKDs age 18–29 with predonation eGFR < 90 to those with eGFR ≥ 90. LKDs with eGFR <90 were matched 1:3 to LKDs with eGFR ≥ 90 using nearest neighbor propensity score matching. Propensity scores were estimated using logistic regression with covariates for age; systolic blood pressure; glucose; BMI; sex; donation year; relationship to recipient, smoking status; and family history of diabetes, hypertension, and cardiovascular disease (CVD). Incidence of death, eGFR < 45, hypertension, diabetes, and CVD were compared between groups using Cox proportional hazards (for death) and Fine-Gray regression models treating death as a competing risk. Results: Of 965 LKDs age 18–29 with follow-up information, median [quartiles] age at donation was 25.4 [22.5, 27.6]; 54.0% were female, 91.6% White, 87% non-Hispanic; 158 (16.4%) had predonation eGFR < 90. LKDs with eGFR < 90 tended to donate during an earlier era (median year: 1982 vs. 1990, p < 0.001) to a first degree relative (86.7% vs. 75.3%, p = 0.008) and have a family history of diabetes (53.8% vs. 40.6%, p = 0.009). During a median follow-up of 25 [12, 37] years no associations were detected between low predonation eGFR and death, eGFR < 45, hypertension, diabetes, or CVD. Results among LKDs age < 25 were similar. Conclusions: Our data do not support increasing the eGFR threshold among young White non-Hispanic donor candidates, reducing one barrier to living donation.