Background: Obesity is a risk factor for poor transplant outcomes in the adult population. The effect of pre-transplant weight on pediatric kidney transplantation is conflicting in the existing literature.
Methods: Data was collected from the Organ Procurement and Transplantation Network (OPTN) database on recipients aged 2-21 years who received a kidney-only transplant from 1987 to 2017. Recipients were categorized into underweight, normal, overweight, and obese cohorts. Using adjusted regression models, the relationship between recipient weight and various graft outcomes (delayed graft function [DGF], acute rejection, prolonged hospitalization, graft failure, mortality) was examined.
Results: 18,261 transplant recipients (mean age 14.1 ± 5.5 years) were included, of which 8.7% were underweight, 14.8% were overweight, and 15% were obese. Obesity was associated with greater odds of DGF (OR 1.3 95% CI 1.13-1.49, p < 0.001), acute rejection (OR 1.23 95% CI 1.06-1.43, p < 0.01), and prolonged hospitalization (OR 1.35 95% CI 1.17-1.54, p < 0.001) as well as greater hazard of graft failure (HR 1.13 95% CI 1.05-1.22, p = 0.001) and mortality (HR 1.19 95% CI 1.05-1.35, p < 0.01). The overweight cohort had an increased risk of graft failure (HR 1.08 95% CI 1.001-1.16, p = 0.048) and increased odds of DGF (OR 1.2 95% CI 1.04-1.38, p = 0.01) and acute rejection (OR 1.18 95% CI 1.01-1.38, p = 0.04). When stratified by age group, the increased risk was realized among younger and older age groups for obese and overweight. Underweight had lower risk of 1-year graft failure (HR 0.82 95% CI 0.71-0.94, p < 0.01), overall graft failure in the 13-17-yr. age group (HR 0.84 95% CI 0.72-0.99, p = 0.03) and acute rejection in the 2-5-yr. age group (OR 0.24 95% CI 0.09-0.66, p < 0.01).
Conclusion: Pre-transplant weight status and age impact pediatric kidney transplant outcomes. Recipient underweight status seems to be protective against adverse outcomes while overweight and obesity may lead to poorer graft and patient outcomes.
Keywords: Children; Obesity; Outcomes; Renal transplant; Weight.