Abstract Body: Background: Although BP is associated with kidney outcomes, its clinical significance in living kidney donors (LKD) is unknown. We aim to examine the association between pre-donation BP and the risk of kidney function decline in LKD.

Methods: A retrospective cohort study using OPTN/SRTR including adult LKD, who underwent donation between 6/1972 and 9/2022, was utilized to examine the association of quartile (Q) of pre-donation SBP and DBP with time-to-event of ≥35% decline in post-donation eGFR from pre-donation eGFR by multiple Cox regression.

Results: Of 174,311 adult LKD, mean±SD age was 41±12 years and 60% were female. Mean pre-donation SBP and DBP were 122±13 and 74±9 mmHg, respectively. Mean pre-donation SBP in Q 1, 2, 3, and 4 were 106±6, 117±2, 126±3, and 140±9 mmHg, respectively and the corresponding DBP were 62±5, 71±2, 78±2, and 86±5 mmHg, respectively. The median (IQR) of pre-donation eGFR was 91 (75, 111) mL/min/1.73 m². Median(IQR) eGFR at immediate post-donation, 6-, 12-, and 24-months post-donation were 50 (40, 62), 54 (44, 67), 55 (45, 68), and 57 (47, 70) mL/min/1.73 m², respectively. Out of 38,780 LKD with post-donation eGFR data at 6, 12, or 24 months, 31,054 had the event of ≥35% decline in post-donation eGFR from pre-donation eGFR with a median time to follow-up of 6.77 months(IQR 5.93, 12.67). The incidence rate of the event was 0.08 person-months. Compared to patients with SBP in Q 1, those with SBP in Q 2, 3, and 4 had a significantly increased risk for the event(HR_{SBP Q2,3,4} 1.05, 1.08, and 1.15; P <0.001 – 0.003) but only patients with DBP in Q 3 and 4 had a significantly increased risk for the event (HR_{SBP Q3,4} 1.04 and 1.09). After adjusting for age, gender, race/ethnicity, U.S. citizenship, education level, history of pre-donation HTN, diabetes, pre-donation BMI, DBP, and urine protein:creatinine ratio, there was a J-shaped association between pre-donation SBP and post-donation eGFR decline and only patients in the Q 2 became significantly associated with lower the risk for the event (HR 0.87, 95%CI 0.76, 0.99; Fig1). The pre-donation DBP – post-donation eGFR association was similar to the SBP – eGFR association but there was no statistically significant in all Q (Fig2). There was no effect-measured modifier for all covariates.

Conclusions: Pre-donation SBP in a normal range(113 - 120 mmHg) is associated with the lowest risk for a post-donation eGFR decline. BP control in the normal range should be achieved for potential LKD.