#2348 Paradoxical association of pre-donation estimated glomerular filtration rate with kidney function decline in living kidney donors

Abstract Background and Aims Living kidney donors (LKD) are at risk for chronic kidney disease (CKD). Whether differences in pre-donation estimated glomerular filtration rates (eGFR) are associated with differences in the rate of post-donation eGFR decline is unclear. We aim to examine the association between pre-donation eGFR and the risk of kidney function decline post-donation. Method A retrospective cohort study using the Organ Procurement and Transplantation Network (OPTN) and Scientific Registry of Transplant Recipients (SRTR) database included LKD with pre- and early post-donation eGFR as well as eGFR at 6, 12, and 24 months after donation. The association between the quartile (Q) of pre-donation eGFR and time to ≥35% decline in post-donation eGFR compared to pre-donation eGFR was examined by competing-risks survival regression with death serving as a competing risk variable. Results Of 129,943 LKD ≥18 years old undergoing donation between October 1987 and September 2022, mean ± SD age was 42 ± 12 years and 61% were female. Mean overall pre-donation eGFR was 95.76 ± 29.80 mL/min/1.732 and mean pre-donation eGFR of LKD in Q1, 2, 3, and 4 were 63.50 ± 8.86, 83.05 ± 4.53, 100.30 ± 5.72, and 136.22 ± 23.69 mL/min.1.73 m2, respectively (Ptrend 0.001). Compared to pre-donation eGFR, the mean eGFR at early post-donation was significantly decreased to 53.56 ± 39.81 mL/min.1.73 m2 (mean eGFRpost-pre −43.38 mL/min.1.73 m2; P 0.001), but mean post-donation eGFR at 6, 12, and 24 months continued trending up to 57.58 ± 45.37, 59.28 ± 43.25, and 61.05 ± 42.51 mL/min.1.73 m2, respectively which were significantly greater than early post-donation eGFR (mean eGFR 6mo-post 4.28, eGFR12mo-post 6.01, and eGFR24mo-post 7.82 mL/min.1.73 m2; P 0.001; Fig. 1). Median survival for ≥35% decline in post-donation eGFR was 6.43 months (5.50, 11.30) with an incidence rate of 0.08 person-months. Among 75,220 LKD with follow-up data, 58,985 (78%) had the event and 15 (0.02%) died. Compared to LKD with pre-donation eGFR in Q1, LKD in other Q had a significantly higher risk for ≥35% decline in post-donation eGFR with a positively graded association (HR (95% CI)Q2 1.28 (1.23, 1.32); HRQ3 1.41 (1.36, 1.46); and HRQ4 1.60 (1.55, 1.65)). After adjusting for age, gender, race, body mass index, history of hypertension, diabetes, U.S. citizen status, education, and the interaction term between the quartile pre-donation eGFR and race, the magnitude of the association increased but the direction remained (HR (95%C I)Q2 1.41 (1.36, 1.47) HRQ3 1.72 (1.65, 1.79), and HRQ4 2.11 (2.02, 2.20). In addition, race was identified as an effect modifier with an increased risk for ≥35% decline in post-donation eGFR observed in Hispanic/Latino LKD (Pinteraction Q 2, Q3, Q4 0.025, 0.005, and 0.001). Conclusion Higher pre-donation eGFR is associated with a greater risk for post-donation eGFR decline especially among Hispanic/Latino LKD. Candidacy for living kidney donation should not be declined based only on eGFR; while some racial-ethnic minorities may be at greater risk even having higher pre-donation eGFR.