Body mass index as a predictor of outcomes among pediatric kidney transplant recipient

Abstract

Controversies exist regarding the impact of obesity on patients undergoing kidney transplantation. We sought to estimate the association between BMI and patient outcomes (survival and graft function) among pediatric kidney transplant patients in the USA. We conducted a retrospective analysis of the United Network for Organ Sharing database (1987-2013), which revealed 13 014 pediatric patients (<18 years old) who underwent primary kidney transplantation. Patients were stratified into five BMI categories established by the World Health Organizations according to their Z score, which is based on age, gender and BMI. The -2, 0, and +2 categories were collapsed and served as the reference group, while the -3 (thin) and +3 (obese) categories were evaluated for differences in graft and patient survival. The survival rates between these categories were compared using the Kaplan-Meier estimator. Cox proportional hazards models were constructed to adjust for recipient and donor characteristics to estimate the risk of graft loss and mortality associated with BMI. Logistic regression models were estimated to evaluate whether there was an association between BMI and DGF. There were no differences in overall patient (P=.1655) or graft (P=.1688) survival between the severely thin, normal, and obese patients. Adjusted models also revealed no statistically significant differences in graft or patient survival. There were no differences in the odds of DGF (both unadjusted and adjusted) among the three groups. The prevalence of obesity is increasing among children who present for kidney transplant in the USA. In this national study of pediatric kidney transplant recipients, there was no difference in graft or patient survival and no differences in rates of DGF among obese children compared to normal and underweight children undergoing kidney transplantation.

Effect of pre and post-transplant body mass index on pediatric kidney transplant outcomes

“…Also, Winnicki et al showed that obese recipients had an increased risk of graft failure compared to normal weight recipients [ 4 ]. On the contrary, Dick et al found no difference in mortality, graft survival, or DGF among children < 18 years classified as severely thin, normal weight, and severely obese using World Health Organization (WHO) criteria which came in contrast to our results [ 22 ]. Mitsnefes et al as well reported that obese children had an equivalent risk of developing acute rejection as normal weight children in the first year post-transplant [ 3 ].…”

Malnutrition and immune cell subsets in children undergoing kidney transplantation

“…Additionally, children who were overweight at baseline, or who were exposed to steroids, were most likely to develop obesity post‐kidney transplantation 8 . Finally, obesity has also been associated with worse post‐transplant outcomes including increases in rates of delayed graft function (DGF), acute rejection and increased hospitalizations as well as decreased graft, and patient survival 7,15–17 …”

“…8 Finally, obesity has also been associated with worse post-transplant outcomes including increases in rates of delayed graft function (DGF), acute rejection and increased hospitalizations as well as decreased graft, and patient survival. 7,[15][16][17] With regard to undernutrition, chronically ill children in general are at higher risk for undernutrition with one study finding that greater than 30% of chronically ill children attending outpatient visits are malnourished. 9 Furthermore, end-stage renal disease is associated with undernutrition with approximately 20%-45% of children classified with this malnourished state.…”

The Conundrum of High Body Mass Index in Kidney Transplant Patients

“…In addition, there is evidence of a direct causal connection between obesity and CKD, with a faster progression of CKD to end-stage renal disease (ESRD), due to the underlying renal hyperfiltration driven by the weight excess [5]. However, literature has shown that ESRD obese patients benefit from transplantation as do non-obese patients [6][7][8], and even in the paediatric population, no difference in graft or patient survival are reported among different BMI categories [9].…”