Kidney transplantation from small pediatric donors: does recipient body mass index matter?

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.

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).

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.

Increasing recipient BMI is not a clear risk factor for outcomes or graft function after transplantation with small pediatric-donor kidneys.