Postdonation Weight Gain Is Associated with Lower Likelihood of Recovering Predonation eGFR

Background: Living kidney donors with obesity (body mass index (BMI) ≥ 30 kg/m2) at donation have a lower likelihood of recovery of estimated glomerular filtration rate (eGFR) post-donation. We sought to understand whether early post-donation changes in weight are also associated with the likelihood of eGFR recovery. Methods: Using data from the Scientific Registry of Transplant Recipients, we examined 91,653 adult living kidney donors (1999-2023) with pre-operative serum creatinine and height/weight measurements and at least one creatinine and weight measurement post-donation. We utilized the 2021 CKD-EPI equation to estimate eGFR, and Cox proportional hazards regression with a time-varying covariate for change in BMI was utilized to estimate the likelihood of recovering at least 60% of pre-donation eGFR, censoring for last creatinine measurement. Results: Among a cohort that was majority female (63%) and white (85%), donors were median age 43 years (IQR: 33-52) and median BMI 26.6 kg/m2 (IQR: 24.0-29.6). Median pre-donation serum creatinine was 0.80 mg/dL (IQR: 0.70-0.93), with a median mean arterial pressure of 90 mmHg (IQR: 83.3-96.3). On unadjusted analyses, gaining > 5% BMI (a clinically relevant threshold for risk of cardiovascular and obesity-related complications) was associated with a 7% lower likelihood of recovering 60% of pre-donation eGFR (HR: 0.93, 95% CI: 0.92-0.94, p< 0.001), while losing > 5% BMI was positively associated with recovery (HR: 1.02, 95% CI: 1.00-1.03, p=0.01). After adjusting for relevant baseline factors, gaining > 5% BMI remained significantly associated with a lower likelihood of eGFR recovery (aHR: 0.91, 95% CI: 0.90-0.93, p < 0.001) (Figure). Conclusion: Weight change in the early post-donation period is a modifiable factor that is associated with recovery of kidney function. These findings highlight the need for a greater commitment to support living donors in maintaining healthy lifestyles post-donation and prospective studies of living donor follow-up. Funding: NIDDK Support