Background: The influence of recipient body mass index (BMI) on pediatric-donor kidney transplant outcomes is unclear. We aimed to determine graft survival and functional outcomes of pediatric-donor kidneys compared with adult kidneys stratified by recipient BMI group.
Methods: Scientific Registry of Transplant Recipients data for recipients from 1996 to 2010 were reviewed. Donors were categorized by transplant type, pediatric single kidney transplant (SKT, n=3712), en bloc kidney transplant (EBK, n=1517), or adult standard criteria donor (SCD, n=66,741). Recipients were stratified by BMI tertiles (<24, 24-29, and >29 kg/m).
Results: SKT and EBK from donors ≤40 kg conferred similar risks of adjusted death-censored graft survival relative to SCDs regardless of recipient BMI except for EBK transplants in recipients with BMI <24 where the effect was protective (adjusted hazard ratio [aHR] 0.71, 95% confidence interval [CI] 0.56-0.94). SKT from donors ≤20 kg conferred worse death-censored graft survival in recipients with BMI <24 (aHR 1.3, 95% CI 1.0-1.6) and BMI >29 (aHR 1.5, 95% CI 1.1-2.0); however, most of the risk appeared early, and the effect was abrogated with reanalysis conditional on 1-year graft survival. Compared with SCDs, 1-year glomerular filtration rates of SKT from donors ≤20 kg were significantly higher when transplanted into recipients with BMI <24 (P<0.01) and similar in the other BMI groups.
Conclusion: Increasing recipient BMI is not a clear risk factor for outcomes or graft function after transplantation with small pediatric-donor kidneys.