Investigating the controversial link between pediatric obesity and graft survival in kidney transplantation.

Background: Childhood obesity is a significant public health concern, particularly amongst children with chronic kidney disease requiring kidney transplant (KT). Obesity, defined as a body mass index (BMI) of 30 kg/m² or greater, is prevalent in this population and is associated with disease progression. While BMI influences adult KT eligibility, its impact on pediatric transplant outcomes remains unclear. This study investigates the effect of BMI on graft survival and patient outcomes, addressing gaps in the literature and examining disparities across BMI classifications.

Aim: To assess the impact of BMI classifications on graft and patient survival following KT.

Methods: A retrospective cohort study analyzed 23081 pediatric transplant recipients from the Standard Transplant Analysis and Research database (1987-2022). Patients were grouped into six BMI categories: Underweight, healthy weight, overweight, and Class 1, 2, and 3 obesity. Data were analyzed using one-way way analysis of variance, Kruskal-Wallis tests, Chi-squared tests, Kaplan-Meier survival analysis with log-rank tests, and Cox proportional hazard regressions. Statistical significance was set at P < 0.05.

Results: Class 3 obese recipients had lower 1-year graft survival (88.7%) compared to healthy-weight recipients (93.1%, P = 0.012). Underweight recipients had lower 10-year patient survival (81.3%, P < 0.05) than healthy-weight recipients. Class 2 and 3 obese recipients had the lowest 5-year graft survival (67.8% and 68.3%, P = 0.013) and Class 2 obesity had the lowest 10-year graft survival (40.7%). Cox regression identified increases in BMI category as an independent predictor of graft failure [hazard ratio (HR) = 1.091, P < 0.001] and mortality (HR = 1.079, P = 0.008). Obese patients experienced longer cold ischemia times (11.6 and 13.1 hours vs 10.2 hours, P < 0.001). Class 3 obesity had the highest proportion of Black recipients (26.2% vs 17.9%, P < 0.001).

Conclusion: Severe obesity and underweight status are associated with poorer long-term outcomes in pediatric KT recipients, emphasizing the need for nuanced transplant eligibility criteria addressing obesity-related risks and socioeconomic disparities.