Effect of BMI on allograft function and survival in pediatric renal transplant recipients

Changes in graft outcomes in recipients <10 kg over 25 years of pediatric kidney transplantation in the United States

BACKGROUND

Kidney transplant (KT) was initially associated with poor outcomes, especially in smaller recipients. However, pediatric transplantation has evolved considerably over time. We investigated the impact of weight at the time of transplant and whether outcomes changed over 25 years for <10 kg recipients.

METHODS

Using the UNOS database, pediatric recipient outcomes were analyzed between 1/1/99 and 12/31/14. KT weight was stratified: <8.6 kg (mean weight of recipients <10 kg), 8.6-9.9 kg, 10-14.9 kg, 15-29.9 kg, and ≥30 kg. Outcomes in recipients <10 kg were then compared between 1990-1999 and 2000-2014.

RESULTS

17 314 pediatric KT recipients were included; 518 (3%) had a transplant weight <10 kg. The highest rates of allograft loss and death were in recipients <8.6 kg and ≥30 kg. Recipients <8.6 kg also had higher rates of delayed graft function, rejection, and longer hospital length of stay. In the multivariable Cox regression model, transplant weight was not a predictor of allograft loss. When compared with recipients <8.6 kg, patient survival hazard ratios associated with recipient weight of 10-14.9 kg, 15-29.9 kg, and ≥30 kg were 0.61 (95%CI: 0.4, 1), 0.42 (95%CI: 0.3, 0.7) and 0.32 (95%CI: 0.2, 0.6), respectively. In the later era of transplant, recipients <10 kg had improved outcomes on univariate analysis; however, the era of transplantation was not an independent predictor of allograft loss or patient survival in Cox regression models.

CONCLUSIONS

Outcomes in children weighing 8.6-9.9 kg at the time of KT were similar to higher weight groups and improved over time; however, special precautions should be taken for recipients <8.6 kg at the time of transplant.

Associations of body mass index (BMI) and BMI change with progression of chronic kidney disease in children

BACKGROUND

Obesity is prevalent among children with chronic kidney disease (CKD) and is associated with cardiovascular disease and reduced quality of life. Its relationship with pediatric CKD progression has not been described.

METHODS

We evaluated relationships between both body mass index (BMI) category (normal, overweight, obese) and BMI z-score (BMIz) change on CKD progression among participants of the Chronic Kidney Disease in Children study. Kaplan-Meier survival curves and multivariable parametric failure time models depict the association of baseline BMI category on time to kidney replacement therapy (KRT). Additionally, the annualized percentage change in estimated glomerular filtration rate (eGFR) was modeled against concurrent change in BMIz using multivariable linear regression with generalized estimating equations which allowed for quantification of the effect of BMIz change on annualized eGFR change.

RESULTS

Participants had median age of 10.9 years [IQR: 6.5, 14.6], median eGFR of 50 ml/1.73 m2 [IQR: 37, 64] and 63% were male. 160 (27%) of 600 children with non-glomerular and 77 (31%) of 247 children with glomerular CKD progressed to KRT over a median of 5 years [IQR: 2, 8]. Times to KRT were not significantly associated with baseline BMI category. Children with non-glomerular CKD who were obese experienced significant improvement in eGFR (+ 0.62%; 95% CI: + 0.17%, + 1.08%) for every 0.1 standard deviation concurrent decrease in BMI. In participants with glomerular CKD who were obese, BMIz change was not significantly associated with annualized eGFR change.

CONCLUSION

Obesity may represent a target of intervention to improve kidney function in children with non-glomerular CKD. A higher resolution version of the Graphical abstract is available as Supplementary information.

Malnutrition Patterns in Children with Chronic Kidney Disease

Malnutrition is frequent in children with chronic kidney disease (CKD). Apart from undernutrition and protein energy wasting (PEW), overnutrition prevalence is rising, resulting in fat mass accumulation. Sedentary behavior and unbalanced diet are the most important causal factors. Both underweight and obesity are linked to adverse outcomes regarding renal function, cardiometabolic risk and mortality rate. Muscle wasting is the cornerstone finding of PEW, preceding fat loss and may lead to fatigue, musculoskeletal decline and frailty. In addition, clinical data emphasize the growing occurrence of muscle mass and strength deficits in patients with fat mass accumulation, attributed to CKD-related wasting processes, reduced physical activity and possibly to obesity-induced inflammatory diseases, leading to sarcopenic obesity. Moreover, children with CKD are susceptible to abdominal obesity, resulting from high body fat distribution into the visceral abdomen compartment. Both sarcopenic and abdominal obesity are associated with increased cardiometabolic risk. This review analyzes the pathogenetic mechanisms, current trends and outcomes of malnutrition patterns in pediatric CKD. Moreover, it underlines the importance of body composition assessment for the nutritional evaluation and summarizes the advantages and limitations of the currently available techniques. Furthermore, it highlights the benefits of growth hormone therapy and physical activity on malnutrition management.

An ethical analysis of obesity as a contraindication of pediatric kidney transplant candidacy

The inclusion of body mass index (BMI) as a criterion for determining kidney transplant candidacy in children raises clinical and ethical challenges. Childhood obesity is on the rise and common among children with kidney failure. In addition, obesity is reported as an independent risk factor for the development of CKD and kidney failure. Resultantly, more children with obesity are anticipated to need kidney transplants. Most transplant centers around the world use high BMI as a relative or absolute contraindication for kidney transplant. However, use of obesity as a relative or absolute contraindication for pediatric kidney transplant is controversial. Empirical data demonstrating poorer outcomes following kidney transplant in obese pediatric patients are limited. In addition, pediatric obesity is distributed inequitably among groups. Unlike adults, most children lack independent agency to choose their food sources and exercise opportunities; they are dependent on their families for these choices. In this paper, we define childhood obesity and review (1) the association and impact of obesity on kidney disease and kidney transplant, (2) existing adult guidelines and rationale for using high BMI as a criterion for kidney transplant, (3) the prevalence of childhood obesity among children with kidney failure, and (4) the existing literature on obesity and pediatric kidney transplant outcomes. We then discuss ethical considerations related to the use of obesity as a criterion for kidney transplant.

Malnutrition and immune cell subsets in children undergoing kidney transplantation

BACKGROUND

Malnutrition, including obesity and undernutrition, among children is increasing in prevalence and is common among children on renal replacement therapy. The effect of malnutrition on the pre-transplant immune system and how the pediatric immune system responds to the insult of both immunosuppression and allotransplantation is unknown. We examined the relationship of nutritional status with post-transplant outcomes and characterized the peripheral immune cell phenotypes of children from the Immune Development of Pediatric Transplant (IMPACT) study.

METHODS

Ninety-eight patients from the IMPACT study were classified as having obesity, undernutrition, or normal nutrition-based pre-transplant measurements. Incidence of infectious and alloimmune outcomes at 1-year post-transplantation was compared between nutritional groups using Gray's test and Fine-Gray subdistribution hazards model. Event-free survival was estimated by Kaplan-Meier method and compared between groups. Differences in immune cell subsets between nutritional groups over time were determined using generalized estimating equations accounting for the correlation between repeated measurements.

RESULTS

We did not observe that nutritional status was associated with infectious or alloimmune events or event-free survival post-transplant. We demonstrated that children with obesity had distinct T-and B-cell signatures relative to those with undernutrition and normal nutrition, even when controlling for immunosuppression. Children with obesity had a lower frequency of CD8 Tnaive cells 9-month post-transplant (p < .001), a higher frequency of CD4 CD57 + PD1- T cells, and lower frequencies of CD57-PD1+ CD8 and CD57-PD1- CD8 T cells at 12-month transplant (p < .05 for all).

CONCLUSIONS

Children with obesity have distinct immunophenotypes that may influence the tailoring of immunosuppression.

Epidemiology of pediatric chronic kidney disease/kidney failure: learning from registries and cohort studies

Although the concept of chronic kidney disease (CKD) in children is similar to that in adults, pediatric CKD has some peculiarities, and there is less evidence and many factors that are not clearly understood. The past decade has witnessed several additional registry and cohort studies of pediatric CKD and kidney failure. The most common underlying disease in pediatric CKD and kidney failure is congenital anomalies of the kidney and urinary tract (CAKUT), which is one of the major characteristics of CKD in children. The incidence/prevalence of CKD in children varies worldwide. Hypertension and proteinuria are independent risk factors for CKD progression; other factors that may affect CKD progression are primary disease, age, sex, racial/genetic factors, urological problems, low birth weight, and social background. Many studies based on registry data revealed that the risk factors for mortality among children with kidney failure who are receiving kidney replacement therapy are younger age, female sex, non-White race, non-CAKUT etiologies, anemia, hypoalbuminemia, and high estimated glomerular filtration rate at dialysis initiation. The evidence has contributed to clinical practice. The results of these registry-based studies are expected to lead to new improvements in pediatric CKD care.

Body Fat Distribution, Adipocytokines Levels and Variability in Associated Genes and Kidney Transplant Outcomes

Introduction: Body fat distribution is known to contribute to a variety of pathologies. Research Questions: We aimed to assess whether this distribution is associated with clinical outcomes in renal transplant recipients (RTR) and to examine its relationship with leptin and adiponectin gene variants and plasma concentrations. Design: Bioelectrical impedance analyses were performed in 236 RTR. Leptin/adiponectin levels were measured by immunoassay and relevant polymorphisms in the leptin receptor (LEPR) and adiponectin (ADIPOQ) genes were identified. Associations were assessed by logistic regression modeling. Results: The waist-to-height ratio (WHr) displayed a significant association with delayed graft function, acute rejection and post-transplant diabetes mellitus, with OR values of 2.04 (1.02-4.08) p = 0.045; 3.08 (1.22-7.79) p = 0.017 and 2.79 (1.16-6.74) p = 0.022, respectively. Waist circumference was linked to delayed graft function [OR = 1.03 (1.01-1.05), p = 0.025] and AR [OR = 1.041 (1.01-1.07), p = 0.009]. Leptin levels were significantly higher in patients who experienced rejection [19.91 ± 23.72 versus 11.22 ± 16.42 ng/ml; OR = 1.021 (1.01-1.04), p = 0.017]. The ADIPOQ rs1501299TT genotype showed a significant association with higher WHr (0.63 ± 0.11 vs 0.59 ± 0.87 for GG/GT genotypes; p = 0.015) and WC values (102.3 ± 14.12 vs 96.38 ± 14.65 for GG/GT genotypes; p = 0.021). Conclusion: WC, and especially WHr, are associated with adverse outcomes in renal transplantation and are affected by variability in the ADIPOQ gene.

Pediatric kidney transplant and cardiometabolic risk: a cohort study

INTRODUCTION

Patients with chronic kidney disease (CKD) are known to have increased cardiovascular risk but there are few data on the risk of pediatric kidney transplant recipients. We aimed to assess the impact of pre- and post-transplant overweight on allograft function and to characterize the evolution of several cardiovascular risk variables over time and their impact.

METHODS

A retrospective analysis of the records of 23 children/adolescents followed at a tertiary center after kidney transplant was conducted. Data on anthropometry and cardiometabolic variables were analyzed before transplant, six and 12 months after the transplant, and at the last follow-up visit. The impact of the variables on allograft function (glomerular filtration rate (GFR)) was estimated by creatinine-based revised Schwartz formula (Cr-eGFR) and was evaluated using nonparametric tests. Results: The 23 patients included in the study had a median age of 6.3 (4.4-10.1) years. Both systolic and diastolic BP z-score values significantly decreased between BMI groups [1.2 (-0.2 - 2.3) vs. 0.3 (-0.4 - 0.6), p=0.027 and 0.8 (-0.4 - 1.3) vs. 0.1 (-0.6 - 0.7), p=0.028, pre-transplant and at the final evaluation, respectively]. During follow-up, GFR values decreased (Cr-GFR: 68.9 (57.7-76.8) vs. 58.6 (48.9-72.9), p=0.033 at 6-months and at the end, respectively). Significant negative correlations between triglycerides and cystatin C-based eGFR (ρ=-0.47, p=0.028) and Cr-Cys-eGFR (ρ=-0.45, p=0.043) at the end of the study were found.

CONCLUSION

Our study showed a high number of overweight children undergoing kidney transplant. A negative correlation between triglycerides and GFR was found, which highlights the importance of managing nutritional status and regular blood lipids evaluation after kidney transplant.

Association of obesity with mortality and clinical outcomes in children and adolescents with transplantation: A systematic review and meta-analysis

Obesity might be associated with mortality and clinical outcomes following transplantation; however, the direction of this relationship has not been well-recognized in youth. The aim of this systematic review and meta-analysis was to investigate the association of obesity with post-transplant mortality and clinical outcomes in children and adolescents. Following a systematic search of observational studies published by December 2018 in PubMed, Scopus, Embase, and Cochrane library, 15 articles with total sample size of 50,498 patients were included in the meta-analysis. The main outcome was mortality and secondary outcomes included acute graft versus host disease (GVHD), acute rejection, and overall graft loss. The pooled data analyses showed significantly higher odds of long term mortality (OR 1.30, 95% CI 1.15-1.48, P < 0.001, I² = 50.3%), short term mortality (OR 1.79, 95% CI 1.19-2.70, P = 0.005, I² = 59.6%), and acute GVHD (OR 2.13, 95% CI 1.5-3.02, P < 0.001, I² = 1.7%) in children with obesity. There were no significant differences between patients with and without obesity in terms of acute rejection (OR 1.07, 95% CI 0.98-1.16, P = 0.132, I² = 7.5%) or overall graft loss (OR 1.04, 95% CI 0.84-1.28, P = 0.740, I² = 51.6%). This systematic review and meta-analysis has stated higher post-transplant risk of short and long term mortality and higher risk of acute GVHD in children with obesity compared to those without obesity. Future clinical trials are required to investigate the effect of pre-transplant weight management on post-transplant outcomes to provide insights into the clinical application of these findings. This may in turn lead to establish guidelines for the management of childhood obesity in transplantations.

Recipient gender and body mass index are associated with early acute rejection in donation after cardiac death liver transplantation

BACKGROUND

Early acute rejection (EAR) is a common complication after liver transplantation (LT).

AIM

The aim of this study was to evaluate the incidence and risk factors of EAR in donation after cardiac death (DCD) liver transplantation recipients.

METHOD

We retrospectively analysed the data of 461 DCD liver transplants performed during the period from January 2010 to June 2016 to study the relationship between EAR and various clinical factors. EAR was defined as histologically proven acute cellular rejection occurring less than 90 days after transplantation.

RESULT

The median follow-up time for this study was 33.1 months (range: 0.03-92.8 months). Thirty-two (6.9%) patients developed EAR with a median period of 20.5 days (5-88 days) after transplantation. A multivariate analysis revealed that female recipient (hazard ratio: 2.801; P=0.024) and high recipient body mass index (BMI) (hazard ratio: 1.005; P=0.049) were two independent risk factors for early acute rejection.

CONCLUSIONS

In DCD liver transplantation, recipient female gender and high BMI were associated with a higher incidence of EAR, while the use of CD25-Ab and/or MMF had a protective effect.

Peritoneal dialysis catheter removal at the time of renal transplantation: Choosing the optimal candidate

INTRODUCTION

Concurrent peritoneal dialysis (PD) catheter removal during renal transplantation is controversial, with limited evidence supporting this practice. Our objective was to determine the rate of delayed graft function (DGF) in patients on preoperative PD. Additionally, we sought to identify which patients can safely have their PD catheter removed during transplantation due to a low risk of DGF.

METHODS

We conducted a retrospective observational study between June 2011 and December 2015. The primary outcome was the diagnosis of DGF, defined as the need for dialysis within the first week of transplantation. Clinical and transplant factors, including graft type and donor criteria, were assessed for association with the primary outcome. Catheter-related complication rates were also compared between post-transplant PD and hemodialysis (HD).

RESULTS

Of our cohort of 567 patients, 145 patients (25.6%) developed DGF. Obesity (odds ratio [OR] 1.06; 95% confidence interval [CI] 1.00-1.11; p=0.04) and increased perioperative blood loss (OR 1.002; 95% CI 1.000-1.003; p=0.03) were predictors of DGF. Protective factors included living donor (LD) grafts (OR 0.15; 95% CI 0.05-0.49; p=0.002) and intraoperative graft urine production (OR 0.39; 95% CI 0.23-0.65; p<0.001). In our PD cohort, only LD grafts demonstrated lower DGF rates (0 LD vs. 20.8% deceased donor; p=0.003). In terms of post-transplant renal replacement therapy, patients on PD and HD had similar duration of temporary dialysis (one day PD vs. two days HD; p=0.48) and catheter-related complication rates (4.5% PD vs. 2.6% HD; p=0.30).

CONCLUSIONS

Carefully selected patients, such as those receiving LD grafts, may benefit from concurrent PD catheter removal.

Association Between Serum Prealbumin Level and Outcomes in Prevalent Kidney Transplant Recipients

OBJECTIVE(S)

Prealbumin, a transport protein mostly synthesized in the liver, is a marker of nutrition. Although decreased prealbumin levels are associated with increased mortality in end-stage kidney disease patients, its association with mortality in kidney transplant recipients remains unknown. We evaluated the association between prealbumin levels and outcomes in kidney transplant recipients.

DESIGN

This was a prospective prevalent cohort study. This study included 991 kidney transplant recipients enrolled from December 31, 2006, to December 31, 2007, and followed over a 6-year period. Sociodemographic, past medical history, clinical, and laboratory data were collected at the study entry. Associations between prealbumin levels and death with functioning graft, all-cause mortality, and graft loss were examined using survival models.

RESULTS

Serum prealbumin levels showed significant negative correlation with estimated glomerular filtration rate (R = -0.28; P < .001) and high-sensitive C-reactive protein (R = -0.24; P < .001). Each 5 mg/dL lower serum prealbumin level was associated with 20% higher risk of death with functioning graft (subdistribution hazard ratio [95% confidence interval]: 1.20 [1.08-1.35]; P = .001), which persisted after multivariable adjustments (subdistribution hazard ratio [95% confidence interval]: 1.13 [1.00-1.28]; P = .039). Qualitatively similar trend was observed in all-cause mortality; however, there was no association between prealbumin levels and graft loss.

CONCLUSION(S)

Lower serum prealbumin level is associated with increased risk of death with functioning graft in prevalent kidney transplant recipients.

Outcomes of underweight, overweight, and obese pediatric kidney transplant recipients

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.