Association of Pre‐Living Kidney Donation Body Mass Index with Post‐Donation Estimated Glomerular Filtration Rate Decline

Abstract

IntroductionObesity is one of the risk factors for chronic kidney disease (CKD). Whether body mass index (BMI) at pre‐living kidney donation is associated with worsening kidney function of the remaining kidney after donation is unclear. We aim to examine the association between pre‐donation BMI and change in post‐donation estimated glomerular filtration rate (eGFR) in living kidney donors.MethodsA single‐center retrospective cohort study included 14 living kidney donors. Associations between pre‐donation BMI and percentage of eGFR decline at 2 and 7 days post‐donation were examined by multiple linear regression.ResultsOf all 14 living kidney donors, mean age±SD was 52.64±13.46 years old and 50% was female. Mean BMI was 26.90±2.66 kg/m2. The majority were overweight (72%) followed by normal weight (21%) and obese (7%). eGFR at 2‐ and 7‐day post‐donation were significantly lower than pre‐donation eGFR (55.59±12.48 vs. 55.29±11.33 vs. 93.39±14.62, p <0.001; Figure 1). Every 1 kg/m2 increase in pre‐donation BMI was associated with 0.1% greater decline in eGFR at 2‐day post‐donation, while eGFR decline was up to 1.4% at 7‐day post‐donation (β2day±SE 0.149±0.716, p 0.861, 95%CI ‐1.668, 1.966; Figure 2A and β7day ±SE 1.368±0.834, p 0.080, 95%CI ‐0.191, 2.928; Figure 2B). After adjusted for age, gender, ethnicity, pre‐donation eGFR, and interaction term between age and pre‐donation eGFR, the magnitude of eGFR decline post‐donation were greater for both 2‐ and 7‐day post‐donation; however, only the 7‐day post‐donation eGFR decline was statistically significant without the interaction between age and pre‐donation eGFR (β2day±SE 0.653±0.977, p 0.525, 95%CI ‐1.657, 2.963, pinteraction 0.045 and β7day±SE 2.068±0.800, p 0.036, 95%CI 0.176, 3.959, pinteraction 0.541).ConclusionsHigher pre‐donation BMI is associated with greater eGFR decline at 7‐day, but not 2‐day, post‐donation. Pathological glomerular hyperfiltration from overweight or obesity may counteract with physiological glomerular hyperfiltration from acquired solitary kidney post‐donation leading to worsening post‐donation eGFR decline.