Longitudinal Follow-Up on Cardiopulmonary Exercise Capacity Related to Cardio-Metabolic Risk Factors in Children With Renal Transplants

Abstract

Background: Children with chronic kidney disease, including those treated with kidney transplantation (KT), have an increased risk of cardiovascular disease. The aim of this study was to examine the cardiopulmonary exercise capacity after KT compared to matched controls, to relate the results to physical activity, blood pressure and biochemical findings and to follow exercise capacity over time.Methods: Patients with KT (n = 38, age 7.7–18 years), with a mean time from transplantation of 3.7 years (0.9–13.0) and mean time in dialysis 0.8 years, were examined at inclusion and annually for up to three years. Healthy controls (n = 17, age 7.3–18.6 years) were examined once. All subjects underwent a cardiopulmonary exercise test, resting blood pressure measurement, anthropometry and activity assessment. Patients also underwent echocardiography, dual-energy X-ray absorptiometry (DXA), 24-h ambulatory BP measurements (ABPM), assessment of glomerular filtration rate (GFR) and blood sampling annually.Results: As compared to healthy controls, KT patients showed decreased exercise capacity measured both as VO2peak (34.5 vs. 43.9 ml/kg/min, p < 0.001) and maximal load (2.6 vs. 3.5 W/kg, p < 0.0001), similarly as when results were converted to z-scores. No significant difference was found in weight, but the KT patients were shorter and had higher BMI z-score than controls, as well as increased resting SBP and DBP z-scores. The patient or parent reported physical activity was significantly lower in the KT group compared to controls (p < 0.001) In the combined group, the major determinants for exercise capacity z-scores were activity score and BMI z-score (β = 0.79, p < 0.0001 and β = −0.38, p = 0.007, respectively). Within the KT group, low exercise capacity was associated with high fat mass index (FMI), low activity score, low GFR and high blood lipids. In the multivariate analysis FMI and low GFR remained predictors of low exercise capacity. The longitudinal data for the KT patients showed no change in exercise capacity z-scores over time.Conclusion: Patients with KT showed decreased exercise capacity and increased BP as compared to healthy controls. Exercise capacity was associated to GFR, physical activity, FMI and blood lipids. It did not improve during follow-up.

Physical performance capacity after pediatric kidney transplant and clinical parameters associated with physical performance capacity

“…It is of note that most of the clinical parameters in the transplant recipients were within normal range and GFR was relatively good, which has to be taken account when interpreting the results. This is one of the few prospective studies reporting physical performance in pediatric transplant recipients and the influence of clinical parameters upon it [21][22][23][24][25].…”

“…The relationship between kidney function and physical performance has remained controversial [ 10 , 23 ]. CKD-related metabolic disorders, chronic inflammation, anemia, and malnutrion are generally accepted risk factors for frailty and attenuated physical performance [ 24 , 25 , 29 , 30 ].…”

“…CKD-related metabolic disorders, chronic inflammation, anemia, and malnutrion are generally accepted risk factors for frailty and attenuated physical performance [ 24 , 25 , 29 , 30 ]. A recent study by Westphal Ladfors et al [ 23 ] reported a significant correlation between GFR and exercise capacity in pediatric kidney transplant recipients, with low GFR predicting low exercise capacity. Our present study, however, did not find a correlation between GFR and exercise capacity, but the fact that mGFR was relatively good among all study subjects may have influenced our findings.…”

Physical activity and the ‘pediatric inactivity triad’ in children living with chronic kidney disease: a narrative review

“…In Sweden, Westphal Ladfors et al 25 found, compared to healthy controls, 38 KTx recipients (median age 13.6 years, 3.7 years post-KTx) had decreased exercise capacity measured by VO 2peak (34.5 vs 43.9 mL/kg/min, respectively). Lower exercise capacity was associated with higher fat mass index, lower physical activity, lower kidney function, and higher blood lipids.…”

“…Similarly, physical activity levels assessed via IPAQ were reportedly lower in 38 KTx patients (median age 13.6 years) compared to a non-CKD healthy group. 25 A study from Italy 26 showed 63% (10/16) of KTx recipients (mean age 16.0 years) had inadequate physical exercise levels, defined as <3 h/week. This was also significantly greater than a matched healthy control group.…”