#2348 Paradoxical association of pre-donation estimated glomerular filtration rate with kidney function decline in living kidney donors
Authors: Tantisattamo Ekamol , Kookanok Chutawat , Noree Wanprapit , Rodsom Kamonluk , Rochanaroon Voramol , Chuenchaem Urairat , Wanichwecharungruang Nisha , Vutthikraivit Possawat , Naunsil Piengpich , Kulthamrongsri Thames , Jariyayothin Irin , Wattanachayakul Phuuwadith 
Published: May 2024

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 &lt;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 &lt; 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 &lt; 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 &lt;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.