Intima media thickness in children undergoing dialysis

Long-term Effects of Kidney Transplantation Compared With Dialysis on Intima-media Thickness in Children-Results From the 4C-T Study

BACKGROUND

Children requiring kidney replacement therapy experience high burden of cardiovascular (CV) disease leading to increased mortality. Intima-media thickness (IMT) indicating atherosclerosis is a validated surrogate marker for future CV events.

METHODS

We investigated the effect of different treatment modalities (dialysis, preemptive kidney transplantation (KTx), late KTx after dialysis) on IMT by multivariable linear mixed-effect modeling. Patients were enrolled in a prospective cohort study.

RESULTS

A total of 261 analyzed children had a mean follow-up of 3 y. Children after preemptive and late KTx had lower levels of IMT when compared with dialysis. Using an interaction term, a significant progression of IMT over time was seen during dialysis (β = 0.0053 mm/y, P   =  0.004). IMT before the start of therapy was the most influential determinant in all models. Low IMT was associated with maintenance steroid treatment after preemptive KTx. High IMT on dialysis was associated with higher systolic blood pressure, lower body mass index, lower serum albumin, and lower bicarbonate.

CONCLUSIONS

IMT remained rather stable in children several years after KTx. In contrast, children on dialysis had higher IMT values, which increased over time. In these children, blood pressure control, calorie and protein intake, and acid-base homeostasis seem important. Taken together, children might profit from early transplantation to limit accumulation of CV risk.

Cardiovascular risk factors in children on dialysis: an update

Cardiovascular disease (CVD) is a life-limiting comorbidity in patients with chronic kidney disease (CKD). In childhood, imaging studies have demonstrated early phenotypic characteristics including increases in left ventricular mass, carotid artery intima-media thickness, and pulse wave velocity, which occur even in young children with early stages of CKD. Vascular calcifications are the signature of an advanced phenotype and are mainly found in adolescents and young adults treated with dialysis. Association studies have provided valuable information regarding the significance of a multitude of risk factors in promoting CVD in children with CKD by using intermediate endpoints of measurements of surrogate parameters of CVD. Dialysis aggravates pre-existing risk factors and accelerates the progression of CVD with additional dialysis-related risk factors. Coronary artery calcifications in children and young adults with CKD accumulate in a time-dependent manner on dialysis. Identification of risk factors has led to improved understanding of principal mechanisms of CKD-induced damage to the cardiovascular system. Treatment strategies include assessment and monitoring of individual risk factor load, optimization of treatment of modifiable risk factors, and intensified hemodialysis if early transplantation is not possible.

Interdialytic weight gain and vasculopathy in children on hemodialysis: a single center study

BACKGROUND

Increased interdialytic weight gain (IDWG) has been associated with poor outcomes in adults, but its impact on hemodialysis vasculopathy in children is unknown.

METHODS

Nineteen patients (age 9 to 19 years old) with a median hemodialysis duration of 10.4 months were enrolled. Cardiovascular evaluation included left ventricular mass index (LVMI), pulse wave velocity (PWV), and carotid intima-media thickness (cIMT) measurements. PWV and cIMT were expressed as z-scores based on reference values in healthy children. Blood pressure (BP) evaluation consisted in a 24-h ambulatory BP monitoring. Mean IDGW and residual urine output during the 6 months prior to cardiovascular examination were calculated.

RESULTS

Increased cIMT, LVMI, and PWV was observed in 11 (57.9%), 7 (36.8%), and 5 (26.3%) patients respectively, while BP was normal in all patients. Median IDWG was 3.5% (1.8-6.7). Residual urine output and BP status did not significantly differ between patients with IDWG ≥ or < 4%. After linear regression, IDWG was correlated to cIMT z-score (r² = 0.485, p = 0.001), but not to PWV z-score (r² = 0.04, p = 0.415) and LVMI (r² = 0.092, p = 0.206). After univariate logistic regression, IDWG ≥ 4% was significantly associated to increased cIMT (above 1.65 SDS) (odds ratio 12.25, 95% confidence interval 1.08-138.988). The trend toward an increased cIMT with IDWG ≥ 4% was observed in both patients with short and long dialysis vintage.

CONCLUSIONS

High IDWG is associated with increased cIMT in hemodialyzed children independently of BP control and dialysis vintage. This observation reinforces the importance of interventions to avoid IDWG in hemodialyzed children.

Risk of Stroke in Elderly Dialysis Patients

Despite the current knowledge about the risk of stroke and its related factors in general population, this issue in elderly patients receiving dialysis remains unresolved. Firstly, to compare the risk of stroke between hemodialysis (HD) and peritoneal dialysis (PD), data on 13,065 incident dialysis patients (aged ≥ 65 years; 10,675 in HD and 2,390 in PD) were retrieved from the Korean Health Insurance dataset. Secondly, to identify the risk factors of stroke amongst various clinical and laboratory parameters in HD, 980 elderly patients were retrospectively analyzed using an independent prospective cohort from 31 dialysis centers. For a mean duration of 1.8 years (maximum of 5 years), the risk of all cardiovascular diseases (ischemic heart disease and stroke) did not differ between HD and PD. However, when analyses were conducted separately by subtype, the risk of stroke, not ischemic heart disease, was significantly higher in HD patients than in PD patients. When the risk factors of stroke were probed after HD for a mean duration of 2.6 years (maximum of 7 years), the absolute dependence on social support, a previous history of cardiovascular disease, high levels of low-density lipoprotein cholesterol, and the use of a high number of anti-hypertensive drugs were identified as being significant. Based on the discrepancy of stroke risk between modalities and the HD-tailored risk factors of stroke, the monitoring and management of these factors may be a key strategy to reduce the risk of stroke in elderly patients receiving dialysis.

Hemoglobin of 12 g/dl and above is not associated with increased cardiovascular morbidity in children on hemodialysis

In adults on chronic hemodialysis, achieving a hemoglobin concentration of 12g/dl and above with erythropoiesis stimulating agents leads to increased cardiovascular events and mortality, but this may not be true in children. Therefore, we conducted a retrospective cohort study of pediatric patients (under 18) from the Centers for Medicare and Medicaid Services End Stage Renal Disease (ESRD) Clinical Performance Measures (CPM) project (2000 to 2008) merged with the United States Renal Data System. Hemoglobin was determined from the Clinical Performance Measures data, and beginning annually on January 1st of the next year, patients were followed for up to 1 year. We determined the outcomes (mortality, hospitalization, and cardiovascular events) during follow-up by hemoglobin group at baseline. Models were adjusted for demographic and clinical characteristics of 1569 children studied. The hemoglobin 12 g/dl and above group was older, had fewer years of ESRD, and was more often transplanted. Inpatient and outpatient visits for congestive heart failure, cardiomyopathy, and valvular heart disease were most common in the hemoglobin under 10g/dl group and the frequency of these diagnoses decreased with increasing hemoglobin. The hazard ratio of all-cause mortality (0.33, 95% confidence interval 0.14-0.81) and the adjusted relative rate of all-cause hospitalizations (0.81, 0.74-0.89) were significantly lower in the hemoglobin 12 g/dl and above group. Cardiovascular hospitalizations were significantly higher in the hemoglobin under 10g/dl group (1.31, 1.05-1.64). Thus, in children on hemodialysis, hemoglobin 12g/dl and above is not associated with increased cardiovascular visits, mortality, or all-cause and cardiovascular-related hospitalizations.

The impact of dialysis modality on novel markers of stress reaction, matrix remodeling and endothelial damage in children on chronic dialysis

BACKGROUND/AIMS

Dialysis triggers stress reaction, matrix remodeling and endothelial damage, but little is known about the changes it induces on selected heat shock proteins (Hsp90α), adhesion molecules (E-cadherin, sE-selectin), metalloproteinases (MMP-8) and their extracellular inducer (EMMPRIN). The aim of this study was to assess serum concentrations of the above-mentioned parameters in children on chronic dialysis.

METHODS

19 patients on hemodialysis (HD), 22 children on peritoneal dialysis (PD) and 30 age-matched controls were examined. Serum concentrations of parameters were assessed by ELISA.

RESULTS

Hsp90α, MMP-8, EMMPRIN and E-cadherin concentrations were significantly increased in children on dialysis vs. controls and higher levels were in HD than PD patients. There was no difference in the level of sE-selectin between HD and PD modalities. A single HD session diminished Hsp90α, MMP-8, EMMPRIN and E-cadherin values, but had no impact on sE-selectin levels.

CONCLUSIONS

Hemodialysis evokes stress reaction, matrix and endothelium destruction, to a greater extent than peritoneal dialysis. Single hemodialysis influences circulating cells rather than endothelial cells.

Carotid intima media thickness, oxidative stress, and inflammation in children with chronic kidney disease

OBJECTIVE

We evaluated the association between inflammation and oxidative stress with carotid intima media thickness (cIMT) and elasticity increment module (E(inc)) in pediatric patients with chronic kidney disease (CKD).

METHODS

This analytical, cross-sectional study assessed 134 children aged 6-17 years with CKD. Anthropometric measurements and biochemistry of intact parathyroid hormone (iPTH), high-sensitivity C-reactive protein (CRP), interleukin (IL)-6, IL-1β, reduced glutathione (GSH), malondialdehyde, nitric oxide, and homocysteine were recorded. Bilateral carotid ultrasound (US) was taken. Patients were compared with controls for cIMT and E(inc) using ≥ 75 percentile (PC).

RESULTS

Mean cIMT was 0.528 ± 0.089 mm; E(inc) was 0.174 ± 0.121 kPa × 10(3); cIMT negatively correlated with phosphorus (r -0.19, p =0.028) and the calcium × phosphorus (Ca × P) product (r -0.26, p =0.002), and positively with iPTH (r 0.19,p =0.024). After adjusting for potential confounders, hemodialysis (HD) (β=0.111, p =<0.001), automated peritoneal dialysis (APD) (β=0.064, p =0.026), and Ca x P product(β=-0.002, p =0.015) predicted cIMT (R(2)=0.296). In patients on dialysis, HD (β=0.068, p =0.010), low-density lipoprotein cholesterol (LDL-C) (β=0.001, p =0.048), and GSH(β=-0.0001, p=0.041) independently predicted cIMT (R(2)=0.204); HD, hypoalbuminemia, and high iPTH increased the risk of increased cIMT. In dialysis, E(inc) was inversely associated with GSH, and in predialysis, Ca × P correlated with/predicted E(inc) (β=0.001, p =0.009).

CONCLUSIONS

cIMT and E(inc) strongly associate with several biochemical parameters and GSH but not with other oxidative stress or inflammation markers.

Phosphate is a vascular toxin

Elevated phosphate (P) levels are seen in advanced renal failure and, together with dysregulated calcium, parathyroid hormone and vitamin D levels, contribute to the complex of chronic kidney disease-mineral and bone disease (CKD-MBD). Converging evidence from in vitro, clinical and epidemiological studies suggest that increased P is associated with vascular calcification and mortality. When vessels are exposed to high P conditions in vitro, they develop apoptosis, convert to bone-like cells and develop extensive calcification. Clinical studies in children on dialysis show that high P is associated with increased vessel wall thickness, arterial stiffness and coronary calcification. Epidemiological studies in adult dialysis patients demonstrate a significant and independent association between raised P and mortality. Importantly, raised P is associated with cardiovascular changes even in pre-dialysis CKD, and also in subjects with normal renal function but high P. All P binders can effectively reduce serum P, and this decrease is linked to improved survival. Raised serum P triggers the release of fibroblast growth factor 23 (FGF-23), which has the beneficial effect of increasing P excretion in early CKD, but is increased several 1,000-fold in dialysis, and may be an independent cardiovascular risk factor. Both FGF-23 and its co-receptor Klotho may have direct effects on the vasculature leading to calcification. Fascinatingly, disturbances in FGF-23-Klotho and raised P have also been associated with premature aging. These data suggest that high P levels have adverse vascular effects and that maintaining the serum P levels in the normal range reduces cardiovascular risk and mortality.