Prevalence, risk factors, and consequences of overweight in children and adolescents who underwent renal transplantation--short- and medium-term analysis

Incidence and Risk Factors of Obesity in Childhood Solid-Organ Transplant Recipients

BACKGROUND

Obesity is a significant public health concern; however, the incidence post solid-organ transplantation is not well reported.

METHODS

This study determined the incidence and risk factors of obesity among pediatric solid-organ transplant recipients (heart, lung, liver, kidney, multiorgan) at The Hospital for Sick Children (2002-2011), excluding prevalent obesity. Follow-up occurred from transplantation until development of obesity, last follow-up, or end of study. Incidence of obesity was determined overall, by baseline body mass index, and organ group. Risk factors were assessed using Cox proportional-hazards regression.

RESULTS

Among 410 (55% male) children, median transplant age was 8.9 (interquartile range [IQR]: 1.0-14.5) years. Median follow-up time was 3.6 (IQR: 1.5-6.4) years. Incidence of obesity was 65.2 (95% confidence interval [CI]: 52.7-80.4) per 1000 person-years. Overweight recipients had a higher incidence, 190.4 (95% CI: 114.8-315.8) per 1000 person-years, than nonoverweight recipients, 56.1 (95% CI: 44.3-71.1). Cumulative incidence of obesity 5-years posttransplant was 24.1%. Kidney relative to heart recipients had the highest risk (3.13 adjusted hazard ratio [aHR]; 95% CI: 1.53-6.40) for obesity. Lung and liver recipients had similar rates to heart recipients. Those with higher baseline body mass index (z-score; 1.72 aHR; 95% CI: 1.39-2.14), overweight status (2.63 HR; 95% CI: 1.71-4.04), and younger transplant age (y; 1.18 aHR; 95% CI: 1.12-1.25) were at highest risk of obesity. Higher cumulative steroid dosage (per 10 mg/kg) was associated with increased risk of obesity after adjustment.

CONCLUSIONS

Among all transplanted children at The Hospital for Sick Children, 25% developed obesity within 5-years posttransplant. Kidney recipients, younger children, those overweight at transplant, and those with higher cumulative steroid use (per 10 mg/kg) were at greatest risk. Early screening and intervention for obesity are important preventative strategies.

Changes in body mass index after pediatric renal transplantation

Significant weight gain following renal transplantation is common in adult and pediatric recipients and mostly depends on receiving higher doses of steroids, changes in mood and feelings, as well as their level of physical activities. This study was performed to evaluate body weight and body mass index (BMI) before and after kidney transplantation in children and adolescents. In this cross-sectional study, 71 pediatric renal transplant recipients (42 boys and 29 girls) were included. World Health Organization criteria were used for comparing Z-score BMI for age in our cases. Overweight was defined as Z-score BMI >+1 SD (standard deviation) and obesity as >+2 SD. At the time of transplantation, the mean age was 10.8 ± 3 years (5-16 years) and based on BMIZ-score, the patients were found to be thin (BMIZs <-2 SD) in 16.9%, normal (BMIZs = -2 to +1 SD) in 67.6%, overweight (>+1 SD to +2 SD) in 9.9%, and obese (BMIZs >+2 SD) in 5.6%.The mean follow-up duration after transplantation was 3.57 ± 1.68 years (1-7 years) and at the time of reevaluation after transplant, their mean age was 14.4 years (6-18 years). The mean BMI was 22 ± 5.3 kg/m², and for BMI grouping, the patients were thin in 7%, normal in 54.9%, overweight in 21.1%, and obese in 17%. Pretransplant thinness (BMIZs <-2 SD) was found in 12 patients (16.9%), equally in boys and girls, and in most of them (83.3%), BMIZs changed to normal or even >+1 SD after transplant. Chronic continuous decrease of glomerular filtration rate (CCD/GFR) was found in 27 cases (38%); 74.1% were male (P = 0.045), hypertriglyceridemia was found in 74.1% (P = 0.023%), hypercholesterolemia in 63% (P = 0.032),and obesity in 18.5% (p = 0.5). The incidence of obesity has tripled after kidney transplantation. It was not a risk factor for graft or patient survival in our experience, whereas pretransplant obesity had some effects on long-term graft outcome.

Can childhood obesity influence later chronic kidney disease?

Childhood overweight and obesity affects more and more children. Whilst associations of childhood overweight with later outcomes such as hypertension, diabetes and cardiovascular disease have been well documented, less is known about the association of childhood overweight and obesity with kidney disease. We review the existing evidence for the association of childhood obesity with markers of childhood and adult kidney disease. Whilst there is some evidence for an association, studies have not been able to distinguish between childhood being a sensitive time to develop later kidney problems, or whether observed associations of childhood obesity with poor outcomes are driven by greater lifelong exposure to obesity.

Long-Term Outcomes of Kidney Transplantation in Children

Kidney transplantation is the preferred treatment for end-stage renal disease (ESRD) in children and confers improved survival, skeletal growth, heath-related quality of life, and neuropsychological development compared with dialysis. Kidney transplantation in children with ESRD results in 10-year patient survival exceeding 90%. Therefore, the long-term management of these patients is focused on maintaining quality of life and minimizing long-term side effects of immunosuppression. Optimal management of pediatric kidney transplant recipients includes preventing rejection and infection, identifying and reducing the cardiovascular and metabolic effects of long-term immunosuppressive therapy, supporting normal growth and development, and managing a smooth transition into adulthood.

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

OBJECTIVE

To determine whether pre-transplant body mass index (BMI) affects renal allograft function and survival in pediatric renal transplant recipients.

STUDY DESIGN

This is a retrospective cohort study using the Organ Procurement and Transplantation Network data from 2000 to 2013 to compare time to total allograft loss (allograft failure or death), prevalence of delayed graft function, prevalence of acute rejection, and estimated glomerular filtration rate (eGFR) post-transplant in pediatric renal transplant recipients categorized by BMI z-score.

RESULTS

A total of 8804 kidney transplant recipients met our inclusion criteria, and of those, 6% were underweight, 14% were overweight, and 17% were obese pre-transplant. The adjusted hazard ratio (HR) for allograft failure was significantly higher for obese recipients compared to normal weight recipients (HR 1.25, 95% CI 1.1, 1.42); for every 1 point increase in BMI z-score, there was a 7% increased hazard of allograft failure (HR 1.07; 95% CI 1.03-1.1, p < 0.001). The prevalence of delayed graft function and acute rejection increased with higher BMI z-score category; however, this difference did not reach statistical significance. eGFR at 1 and 5 years post-transplant decreased with higher BMI z-score although it was only statistically significant at 1 year.

CONCLUSIONS

Obesity is prevalent in pediatric renal transplant recipients, and obese, but not overweight or underweight, pediatric renal transplant recipients have an increased risk of allograft failure. Implementation of effective obesity interventions in pediatric renal transplant recipients is of critical importance to improve longevity of the renal allograft.

Factors Associated With Anthropometric Indicators of Nutritional Status in Children With Chronic Kidney Disease Undergoing Peritoneal Dialysis, Hemodialysis, and After Kidney Transplant

OBJECTIVE

The objective of the study was to demonstrate that there are differences in the factors associated with anthropometric indicators of nutritional status, with particular emphasis on arm indicators, in children with end-stage kidney disease undergoing peritoneal dialysis (PD), hemodialysis (HD), and after kidney transplant (KT).

METHODS

An analytical cross-sectional study of consecutive cases included 130 children and adolescents with end-stage kidney disease undergoing substitutive treatment: 49 patients who underwent KT, 33 undergoing PD, and 47 undergoing HD. Socioeconomic data were obtained from all the 3 groups; anthropometric indicators of nutritional status were calculated. Student's t-test and analysis of variance were used for parametric variables. Chi-square test, Mann-Whitney U test, Kruskal-Wallis test, and odds ratio (OR) were used for nonparametric variables.

RESULTS

The number of parents living as couples was higher for patients who underwent KT (OR = 3.5 [95% confidence interval {CI} 1.34-9.0]) and undergoing PD (OR = 3.0 [95% CI 1.06-8.8]) than those undergoing HD. The number of mothers who worked outside the home was higher for patients who underwent KT and undergoing PD than the mothers of patients undergoing HD (OR = 13.7 [95% CI: 4.56-41.05]; OR = 15.4 [CI 95% 4.8-49], respectively). Family income was higher for patients who underwent KT and undergoing PD (P = .019, P = .093, respectively). More than 40% of patients in all the 3 groups had growth impairment. Body mass index, mid-upper arm circumference, tricipital and subscapular skinfolds, total arm area, and arm fat area were affected in HD and PD groups (9 to 40%), while of the patients who underwent KT, 36.7% were overweight or obese. More than 50% of patients who underwent KT and undergoing HD and PD had involvement in the arm muscular area.

CONCLUSIONS

Socioeconomic conditions are more influential for children in the HD program. The nutritional status of children after KT improves; however, not all anthropometric indicators are fully recovered. Children after KT are up to 9 times more likely to be overweight or obese.

Obesity in pediatric kidney transplant recipients and the risks of acute rejection, graft loss and death

BACKGROUND

Obesity is prevalent in children with chronic kidney disease (CKD), but the health consequences of this combination of comorbidities are uncertain. The aim of this study was to evaluate the impact of obesity on the outcomes of children following kidney transplantation.

METHODS

Using data from the ANZDATA Registry (1994-2013), we assessed the association between age-appropriate body mass index (BMI) at the time of transplantation and the subsequent development of acute rejection (within the first 6 months), graft loss and death using adjusted Cox proportional hazards models.

RESULTS

Included in our analysis were 750 children ranging in age from 2 to 18 (median age 12) years with a total of 6597 person-years of follow-up (median follow-up 8.4 years). Overall, at transplantation 129 (17.2%) children were classified as being overweight and 61 (8.1%) as being obese. Of the 750 children, 102 (16.2%) experienced acute rejection within the first 6 months of transplantation, 235 (31.3%) lost their allograft and 53 (7.1%) died. Compared to children with normal BMI, the adjusted hazard ratios (HR) for graft loss in children who were underweight, overweight or diagnosed as obese were 1.05 [95% confidence interval (CI) 0.70-1.60], 1.03 (95% CI 0.71-1.49) and 1.61 (95% CI 1.05-2.47), respectively. There was no statistically significant association between BMI and acute rejection [underweight: HR 1.07, 95% CI 0.54-2.09; overweight: HR 1.42, 95% CI 0.86-2.34; obese: HR 1.83, 95% CI 0.95-3.51) or patient survival (underweight: HR 1.18, 95% CI 0.54-2.58, overweight: HR 0.85, 95% CI 0.38-1.92; obese: HR 0.80, 95% CI 0.25-2.61).

CONCLUSIONS

Over 10 years of follow-up, pediatric transplant recipients diagnosed with obesity have a substantially increased risk of allograft failure but not acute rejection of the graft or death.

Metabolic consequences of modern immunosuppressive agents in solid organ transplantation

Among other factors, sophistication of immunosuppressive (IS) regimen accounts for the remarkable success attained in the short- and medium-term solid organ transplant (SOT) survival. The use of steroids, mycophenolate mofetil and calcineurin inhibitors (CNI) have led to annual renal graft survival rates exceeding 90% in the last six decades. On the other hand, attrition rates of the allograft beyond the first year have remained unchanged. In addition, there is a persistent high cardiovascular (CV) mortality rate among transplant recipients with functioning grafts. These shortcomings are in part due to the metabolic effects of steroids, CNI and sirolimus (SRL), all of which are implicated in hypertension, new onset diabetes after transplant (NODAT), and dyslipidemia. In a bid to reduce the required amount of harmful maintenance agents, T-cell-depleting antibodies are increasingly used for induction therapy. The downsides to their use are greater incidence of opportunistic viral infections and malignancy. On the other hand, inadequate immunosuppression causes recurrent rejection episodes and therefore early-onset chronic allograft dysfunction. In addition to the adverse metabolic effects of the steroid rescue needed in these settings, the generated proinflammatory milieu may promote accelerated atherosclerotic disorders, thus setting up a vicious cycle. The recent availability of newer agent, belatacept holds a promise in reducing the incidence of metabolic disorders and hopefully its long-term CV consequences. Although therapeutic drug monitoring as applied to CNI may be helpful, pharmacodynamic tools are needed to promote a customized selection of IS agents that offer the most benefit to an individual without jeopardizing the allograft survival.

Improved cardiovascular risk factors in pediatric renal transplant recipients on steroid avoidance immunosuppression: A study of the Midwest Pediatric Nephrology Consortium

Several centers have examined the implementation of immunosuppression protocols that minimize steroid exposure. This study retrospectively examined cardiovascular risk factors in 70 pediatric renal transplant recipients on steroid avoidance-based immunosuppression over three yr compared to matched pediatric patients maintained on chronic corticosteroids. Although higher rates of acute rejection were noted in the steroid-avoidant group (22% vs. 16%, p = 0.034), graft function was similar (67 + 10 mL/min/1.73 m(2) vs. 72 + 12 mL/min/1.73 m(2)) (p = 0.053). The steroid-avoidant group demonstrated improved growth (height z-score -0.41 + 5.9 vs. -1.1 + 0.041) with a decrease in the prevalence of obesity (24% vs. 34%, p = 0.021). Indexed systolic blood pressures were lower beginning at six months post-transplant in the steroid-avoidant group (1.21 + 0.15 vs. 1.51 + 0.22, p = 0.020). Indexed diastolic blood pressures were lower beginning at 12 months post-transplant (0.91 + 0.11 vs. 1.12 + 0.18, p = 0.037). Differences in total serum cholesterol values and serum glucose values were not statistically significant. Beginning at 12 months, a statistically significant decrease in left ventricular mass index (39.2 + 11.3 vs. 49.4 + 14.5, p = 0.014) was noted in patients on steroid-avoidant immunosuppression, which corresponded to a significant decrease in the prevalence of left ventricular hypertrophy in these patients by two yr post-transplant (35% vs. 48%, p = 0.012). Systolic blood pressure and BMI were independent predictors of left ventricular hypertrophy.

Long-term effects of paediatric kidney transplantation

Renal transplantation in paediatric patients usually provides excellent short-term and medium-term results. Early diagnosis of chronic kidney disease and active therapy of end-stage renal disease before and after transplantation enables the majority of children to grow and develop normally. The adverse effects of immunosuppressive medication and reduced graft function might, however, hamper long-term outcomes in these patients and can lead to metabolic complications, cardiovascular disease, reduced bone health, and malignancies. The neurocognitive development and quality of life of paediatric transplant recipients largely depend on the primary diagnosis and on graft function. Poor adherence to immunosuppression is an important risk factor for graft loss in adolescents, and controlled transition to adult care is of utmost importance to ensure a continued normal life. In this Review, we discuss the outcomes and long-term effects of renal transplantation in paediatric recipients, including consequences on growth, development, bone, metabolic, and cardiovascular disorders. We discuss the key problems in the care of paediatric renal transplant recipients and the remaining challenges that should be the focus of future research.

Anorexia nervosa in a pediatric renal transplant recipient and its reversal with cyclosporine

We report a 16-yr-old female who developed AN within a month after renal transplantation and its resolution after switching from tacrolimus to cyclosporine. Her initial maintenance immunosuppressive regimen after renal transplantation consisted of tacrolimus, mycophenolate, and steroid. She had 7 kg weight loss within the first month of transplant with subsequent 10, 12, 17, and 19 kg loss after three, five, seven, and nine months of transplant, respectively. Besides weight loss and disturbances in body image, the patient developed alopecia, bradycardia, and persistent secondary amenorrhea. Upon switching to cyclosporine from tacrolimus nine months after transplant, she started regaining weight with 5 kg gain within two months and 10 kg after four months. She restarted her menstrual cycle, alopecia and bradycardia resolved, and her body image disturbance improved. Here, we describe a very unusual neuropsychiatric side effect of tacrolimus and its resolution with another calcineurin inhibitor, cyclosporine, in an adolescent renal transplant recipient.

Metabolic risk factors and long-term graft function after paediatric renal transplantation

The aim of this study was to evaluate metabolic risk factors and their impact on long-term allograft function in paediatric renal transplant (RTx) patients. We reviewed the medical records of 210 RTx patients who underwent transplantation at a median age of 4.5 years (range 0.7-18.2) and a median follow-up of 7.0 years (range 1.5-18.0). Data on lipid and glucose metabolism, uric acid levels, weight and blood pressure were collected up to 13 years post-RTx, and the findings were correlated with the measured glomerular filtration rate (GFR). Beyond the first year, GFR showed gradual deterioration with a mean decline of 2.4 ml/min/1.73 m(2)/year. Metabolic syndrome, overweight, hypertension and type 2 diabetes were diagnosed in 14-19%, 20-23%, 62-87% and 3-5% of the patients, respectively. These entities showed only mild association with the concomitant or long-term GFR values. Dyslipidaemia was common and hypertriglyceridaemia associated with a lower GFR at 1.5 and 5 years post-RTx (P = 0.008 and P = 0.017, respectively). Similarly, hyperuricaemia was frequent and associated significantly with GFR (P < 0.001). Except for hyperuricaemia and hypertriglyceridaemia, metabolic risk factors beyond the first postoperative year associated modestly with the long-term kidney graft function in paediatric RTx patients.