Patient-Level and Center-Level Factors Associated with Required Predonation Weight Loss among Obese Living Kidney Donors.

BACKGROUND:The proportion of overweight/mildly obese living kidney donors has increased in the past few decades, with significant center variation in the BMI of LKDs. The purpose of this study was to examine factors associated with required pre-donation weight loss among obese (body mass index, BMI, >30kg/m2) living kidney donors (OLKDs). METHODS:This retrospective cohort study surveyed 1097 OLKDs (1979-2020) (mean BMI 33 kg/m2) about their donation experience. Bivariate analyses compared donor demographic and center characteristics by whether the donor reported pre-donation weight loss requirement. Generalized estimating equations (GEE) with logit link were employed to estimate marginal effects of patient and center-level factors. Multiple imputation using chained equations was implemented to account for missing values. RESULTS:Of 1097 OLKDs surveyed, 340 (31.0%) reported pre-donation weight loss requirement. Donors with a pre-donation weight loss requirement had slightly higher pre-donation BMIs and donated in more recent years, at centers performing a lower percentage of living donor nephrectomies and with a lower median BMI. In multivariable logistic regression analysis, we observed transplant year (Odds Ratio (OR): 1.04 per year donation, 95%CI: 1.01-1.07, p=0.005), preoperative BMI (OR: 1.16, 95%CI: 1.05-1.28, p<0.01), preoperative hypertension (OR: 1.61, 95%CI: 1.08-2.40, p=0.02), and center percentage of living donor kidney transplants (OR: 0.99, 95%CI: 0.98-1.00, p=0.02) as significantly associated with a pre-donation weight loss requirement. The study found no differences in likelihood of pre-donation weight loss requirement by race, gender, or age, preoperative creatinine, preoperative metabolic dysfunction, or center level median BMI of living donors. CONCLUSIONS:These results suggest that both center and patient-level factors influence whether OLKDs are required to lose weight prior to donation. Future study is needed to determine whether pre-donation weight loss is associated with improved long-term post-donation outcomes.