Blood pressure in children with chronic kidney disease: a report from the Chronic Kidney Disease in Children study

Pharmacokinetics of olmesartan medoxomil in pediatric patients with hypertension

BACKGROUND

The prevalence and importance of hypertension in younger patients is becoming increasingly recognized; however, only a limited number of clinical trials have been conducted in the pediatric population.

OBJECTIVE

The aim of this study was to characterize the pharmacokinetics and short-term safety of olmesartan medoxomil in children and adolescents with hypertension.

METHODS

An open-label, multicenter, single-dose study was conducted in children and adolescents aged 12 months-16 years who were receiving treatment for hypertension or, if not currently treated for hypertension, had either a systolic blood pressure (SBP) or diastolic blood pressure (DBP).≥95th percentile, or SBP or DBP ≥90th percentile if diabetic or with a family history of hypertension. Patients were stratified by age: 12-23 months (Group 1; none enrolled), 2-5 years (Group 2; n = 4), 6-12 years (Group 3; n = 10), and 13-16 years (Group 4; n = 10). All patients received a single oral dose of olmesartan medoxomil based on the individual's age and bodyweight. Patients aged <6 years received an oral suspension of olmesartan medoxomil at a dose of 0.3 mg/kg of bodyweight (not to exceed 20 mg), those aged ≥6 years who weighed ≥35 kg received olmesartan medoxomil 40 mg tablets, and those who weighed <35 kg received olmesartan medoxomil 20 mg tablets.

RESULTS

In Groups 2, 3, and 4, the weight-adjusted apparent total body clearance (CL/F) of olmesartan medoxomil was 0.100 ± 0.034, 0.062 ± 0.020, and 0.072 ± 0.022 L/h/kg, respectively, and the weight-adjusted apparent volume of distribution (Vd/F) was 0.32 ± 0.16, 0.33 ± 0.14, and 0.49 ± 0.23 L/kg, respectively. CL/F and Vd/F in Groups 3 and 4 were not significantly different. Statistical comparisons between Groups 3 or 4 and Group 2 were not performed due to the small sample size of Group 2 (n = 4). Plasma elimination half-life and time to maximum plasma concentration were similar across the three groups. In Groups 3 and 4, considerable interindividual variability was seen in maximum plasma concentration (C(max)), area under the curve (AUC) from time zero to the last measurable concentration, and apparent clearance, with AUC and C(max) approximately 30% greater in Group 3. Four of 24 (16.7%) patients experienced treatment-emergent adverse events that were all mild in severity and considered not drug-related. No deaths, serious adverse events, or discontinuations due to adverse events occurred in the study.

CONCLUSIONS

Olmesartan medoxomil was well tolerated and demonstrated a pharmacokinetic profile in pediatric patients similar to that of adults when adjusted for body size.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00151814

Role of 11βHSD type 2 enzyme activity in essential hypertension and children with chronic kidney disease (CKD)

BACKGROUND

The mineralocorticoid receptor is protected from excess of glucocorticoids by conversion of active cortisol to inactive cortisone by enzyme 11β-hydroxysteroid dehydrogenase type 2 present in the kidney. The metabolites of cortisol and cortisone are excreted in the urine as tetrahydrocortisol (5αTHF+5βTHF) and tetrahydrocortisone (THE), respectively.

HYPOTHESIS

Patients with chronic kidney disease (CKD) and essential hypertension have a functional defect in their ability to convert cortisol to cortisone, thus leading to the activation of mineralocorticoid receptor.

OBJECTIVE

The objective of the investigation was to study the ratio of urinary steroids (5αTHF+5βTHF) to THE in patients with CKD, postrenal transplant, and essential hypertension and to compare the ratio with controls.

DESIGN/METHODS

We enrolled 44 patients (17 with CKD, eight postrenal transplant, 19 with essential hypertension) and 12 controls. We measured spot urinary 5α-THF, 5β-THF, THE, free active cortisol and inactive cortisone by gas chromatography/mass spectrometry. We collected data on age, sex, cause of kidney disease, height, weight, body mass index, blood pressure, serum electrolytes, aldosterone, and plasma renin activity. Blood pressure percentiles and z-scores were calculated. The glomerular filtration rate was calculated using the modified Schwartz formula.

RESULTS

The ratios of 5αTHF+5βTHF to THE were significantly higher in patients with CKD [mean±sd score (SDS)=1.31±1.07] as compared with essential hypertension (mean±SDS=0.59±0.23; P=0.02) and controls (mean±SDS=0.52±0.25; P=0.01). In the postrenal transplant group, the ratio was not significantly different (mean±SDS=0.71±0.55). The urinary free cortisol to free cortisone ratios were significantly higher in the hypertension and CKD groups as compared with the controls. The 5αTHF+5βTHF to THE ratio negatively correlated with the glomerular filtration rate and positively correlated with systolic and diastolic blood pressure z-scores. The correlation of the blood pressure z-scores with ratios was stronger in the CKD group than the essential hypertension and posttransplant groups.

CONCLUSIONS

We have elucidated a functional deficiency of 11β-hydroxysteroid dehydrogenase type 2 in children with CKD and a subset of essential hypertension. Urinary 5α-THF, 5β-THF, and THE analysis by gas chromatography/mass spectrometry should be a part of routine work-up of CKD and hypertensive patients.

CKiD (CKD in children) prospective cohort study: a review of current findings

Chronic kidney disease (CKD) is a life-long condition associated with substantial morbidity and premature death due to complications from a progressive decrease in kidney function. The incidence and prevalence of all stages of CKD in children continues to increase worldwide. Between 2000 and 2008, the kidney replacement therapy incidence rate in those aged 0-19 years increased 5.9% to 15 per million population, highlighting the importance of CKD research in children. Many comorbid conditions seen in adults with CKD, including cardiovascular disease and cognitive impairment, also are highly prevalent in children, implicitly demonstrating the crucial need for initiating therapy early to improve health outcomes in children with CKD. The CKiD (Chronic Kidney Disease in Children) Study is a prospective cohort study of 586 children aged 1-16 years with an estimated glomerular filtration rate of 30-90 mL/min/1.73 m(2). Since its inception, CKiD has identified risk factors for CKD progression and cardiovascular disease in children with CKD and highlighted the effects of CKD on outcomes unique to children, including neurocognitive development and growth. This review summarizes the findings to date, illustrating the spectrum of CKD-associated complications in children and emphasizing areas requiring further investigation. Taken in sum, these elements stress that initiating treatment at an early age is essential for reducing long-term morbidity and mortality in children with CKD.

Left ventricular function in children and adults after renal transplantation in childhood

BACKGROUND

Renal transplantation improves left ventricular (LV) function, but cardiovascular mortality remains elevated. The aim of this cross-sectional study was to determine whether subclinical abnormalities of LV longitudinal function also persist in patients who underwent renal transplant in childhood.

METHODS

Conventional and speckle tracking echocardiography was performed in 68 renal transplant recipients (34 children and 34 adults, median 9.8 years (range 2.0-28.4 years) after first transplantation and 68 age- and sex-matched healthy controls.

RESULTS

Mean age at first transplantation was 8.8 ± 4.8 years. Forty-three percent had a pre-emptive transplant. Of the remaining, 70% received haemodialysis and 30% peritoneal dialysis on average for 6.9 months. Thirty-one percent of paediatric and 35% of adult patients had hypertension. LV mass index was increased in adult patients (92 ± 24 vs 75 ± 11 g/m(2), P< 0.01). LV diastolic function and exercise capacity were impaired in both paediatric and adult patients. LV longitudinal peak systolic strain and strain rate were comparable in patients and controls. In multivariate analysis, systolic blood pressure and LV diastolic relaxation were the main covariates of LV peak systolic strain and strain rate (all P < 0.01).

CONCLUSIONS

Patients who underwent renal transplantation in childhood have abnormal LV diastolic function and impaired exercise capacity, despite preserved LV longitudinal systolic deformation.

Cardiovascular risk assessment in children following kidney transplantation

CV diseases are the leading cause of death among patients with ESRD. RTX decreases the CV risk; however, it still remains definitely higher than that of the general population. Large multicenter and longitudinal studies are difficult to perform and hard end-points of CV events are usually missing among pediatric population. Thus, appropriate estimation of CV risk is of crucial importance to define the potential hazards and to evaluate the effect of treatments aimed to reduce the risk. A number of validated non-invasive methods are available to assess the extent of CV damage in adults, such as calcification scores, cIMT, aPWV, 24-h ABPM, AASI, and HRV; however, they need adaptation, standardization, and validation in pediatric studies. cIMT and PWV are the most promising methods, as pediatric normative values are already present. The up-to-date treatment of ESRD aims not only to save life, but to offer the patient a life expectancy approaching that of the healthy population and to ensure a reasonable quality of life.

Losartan and enalapril are comparable in reducing proteinuria in children

Angiotensin-converting enzyme inhibitors and angiotensin II type I receptor blockers delay progression of chronic kidney disease and have antiproteinuric effects beyond their effects on blood pressure. They are routinely used in adults; however, their efficacy and safety in children, in whom the causes of chronic kidney disease are significantly different relative to adults, is uncertain. Here we assessed an open-label extension of a previous 3-month blinded trial, in which the efficacy and tolerability of losartan was compared to placebo or amlodipine in 306 normotensive and hypertensive children with proteinuria. In this study, 268 children were re-randomized to losartan or enalapril and followed until 100 patients completed 3 years of follow-up for proteinuria and renal function. The least squares percent mean reduction from baseline in the urinary protein/creatinine ratio was 30.01% for losartan and 40.45% for enalapril. The least squares mean change from baseline in eGFR was 3.3 ml/min per 1.73 m2 for losartan and 7.0 ml/min per 1.73 m2 for enalapril. The incidence of specific adverse events such as hyperkalemia and renal dysfunction was low and similar in both groups. Both were generally well tolerated and, overall, fewer drug-related adverse events occurred with losartan than with enalapril. Thus, in children with proteinuria, losartan and enalapril significantly reduced proteinuria without any appreciable changes in eGFR, effects that were maintained throughout the study. Both losartan and enalapril were generally well tolerated.

Neurocognitive alterations in hypertensive children and adolescents

Hypertensive adults demonstrate performance deficits on neuropsychological testing compared with scores of normotensive controls. This article reviews emerging preliminary evidence that children with hypertension also manifest neurocognitive differences when compared with normotensive controls. Database and single-center studies suggest that children with hypertension manifest deficits on measures of neurocognition and have an increased prevalence of learning difficulties and that children with hypertension associated with obesity may be at increased risk for depression and anxiety. Studies suggesting blunted cerebrovascular reactivity in children with hypertension are also reviewed.

Ambulatory blood pressure patterns in children with chronic kidney disease

Ambulatory blood pressure (BP) monitoring (ABPM) is the best method of detecting abnormal BP in patients with chronic kidney disease (CKD), whose hypertension may be missed with casual BP measurements. We report ABPM findings in 332 children 1 year after entry in the Chronic Kidney Disease in Children cohort study. All of the subjects underwent casual and ambulatory BP measurement. BP was categorized based on casual and ABPM results into normal (42%), white-coat (4%), masked (35%), and ambulatory (14%) hypertension. Only half of the subjects had a normal ABPM. BP load was elevated (>25%) in 52% (n = 172), whereas mean BP was elevated in 32% (n = 105). In multivariate analysis, those using an angiotensin-converting enzyme inhibitor were 89% more likely to have a normal ABPM than those who did not report using an angiotensin-converting enzyme inhibitor (odds ratio, 1.89 [95% CI, 1.17-3.04]). For every 20% faster decline in annualized glomerular filtration rate change, the odds of an abnormal ABPM increased 26% (odds ratio, 1.26 [95% CI, 0.97-1.64]). A 2.25-fold increase in urine protein:creatinine ratio annualized change was associated with a 39% higher odds of an abnormal ABPM (odds ratio, 1.39 [95% CI, 1.06-1.82]). Abnormalities on ABPM are common in children with chronic kidney disease and are strongly associated with known risk factors for end-stage renal disease. Individuals on angiotensin-converting enzyme inhibitors were less likely to have abnormal ABPM, suggesting a possible therapeutic intervention. ABPM should be used to monitor risk and guide therapy in children with chronic kidney disease.

Predictors of blood pressure and its control in pediatric patients receiving dialysis

OBJECTIVE

To evaluate and characterize the degree of blood pressure (BP) control in children on chronic dialysis and to identify significant predictors of hypertension and BP control in these patients.

STUDY DESIGN

Linear and logistic regression models were used to examine trends in BP and BP control in a cross-sectional sample of patients on chronic dialysis aged 1-21 years enrolled in the North American Pediatric Renal Trials and Collaborative Studies registry from 1992-2008.

RESULTS

At 6 months after dialysis initiation, 67.9% of patients had uncontrolled or untreated hypertension, and 57.8% were prescribed antihypertensive medications. More recent year of dialysis initiation was associated with a higher use of antihypertensive medication and lower systolic BP and diastolic BP z scores (P < .001) measured over time from 6 months to 3 years post dialysis initiation. Other factors associated with higher BP included black race, glomerular disease, younger age, hemodialysis (systolic BP only), and antihypertensive use. There were significant differences in BP control by dialysis modality and disease etiology, with patients on hemodialysis or those with glomerular diseases having the highest percentage of uncontrolled hypertension.

CONCLUSIONS

Despite widespread antihypertensive use, many pediatric patients on dialysis are at risk for untreated or uncontrolled hypertension. Additional efforts are needed to improve management of hypertension in these children.

Control of hypertension in treated children and its association with target organ damage

BACKGROUND

The aim of our study was to investigate the control of hypertension (HT) in treated children using ambulatory blood pressure (BP) monitoring (ABPM).

METHODS

We retrospectively reviewed all ABPM studies in our center. Controlled HT was defined as systolic and diastolic BP index (patients' BP divided by the 95th percentile) at daytime and nighttime <1.0 or alternatively as BP load (percentage of BP readings above the 95th percentile) <25% in children on antihypertensive therapy.

RESULTS

A total of 195 ABPM studies were included. The mean age was 13.6 ± 4.0 years. One hundred and thirty two children had renoparenchymal HT, 10 renovascular (RVH), 10 endocrine, 4 cardiovascular, 29 primary (PH) and 5 children other forms of HT. 53% of all children had controlled HT. There was no difference in the prevalence of controlled HT between primary and secondary HT (52% and 53%) using the BP index criterion. Children with renoparenchymal HT had significantly better control of HT than children with RVH (58% vs. 20% P = 0.02). The use of angiotensin-converting enzyme inhibitors (ACEI) monotherapy was significantly more effective in controlling HT than the use of calcium-channel blockers (CCB, P = 0.02). The prevalence of left ventricular hypertrophy in children with uncontrolled HT (assessed in 58 patients) was significantly higher than in children with controlled HT (46% vs. 13%, P < 0.01).

CONCLUSIONS

This is the first pediatric study, to our knowledge, on BP control in hypertensive children using ABPM. It indicates that control of HT is inadequate in ~50% of treated children. Inadequate control of HT is associated with target organ damage in this population.

Cardiovascular disease in children with chronic kidney disease

More than a decade ago, cardiovascular disease (CVD) was recognized as a major cause of death in children with advanced CKD. This observation has sparked the publication of multiple studies assessing cardiovascular risk, mechanisms of disease, and early markers of CVD in this population. Similar to adults, children with CKD have an extremely high prevalence of traditional and uremia-related CVD risk factors. Early markers of cardiomyopathy, such as left ventricular hypertrophy and dysfunction, and early markers of atherosclerosis, such as increased carotid artery intima-media thickness, carotid arterial wall stiffness, and coronary artery calcification, are frequently present in these children, especially those on maintenance dialysis. As a population without preexisting symptomatic cardiac disease, children with CKD potentially receive significant benefit from aggressive attempts to prevent and treat CVD. Early CKD, before needing dialysis, is the optimal time to both identify modifiable risk factors and intervene in an effort to avert future CVD. Slowing the progression of CKD, avoiding long-term dialysis and, if possible, conducting preemptive transplantation may represent the best strategies to decrease the risk of premature cardiac disease and death in children with CKD.

Reliability of resting blood pressure measurement and classification using an oscillometric device in children with chronic kidney disease

OBJECTIVE

To compare the reliability of blood pressure (BP) readings obtained with an oscillometric device with those obtained by auscultation and assess for differences in BP status classification based on the 2 techniques.

STUDY DESIGN

Resting BP was measured by auscultation and with an oscillometric device at the same encounter in 235 subjects enrolled in the Chronic Kidney Disease in Children study. Resting auscultatory BP values were averaged and compared with averaged oscillometric readings. BP agreement by the 2 methods was assessed using Bland-Altman plots, and BP status classification agreement was assessed by calculation of kappa statistics.

RESULTS

Oscillometric BP readings were higher than auscultatory readings, with a median paired difference of 9 mm Hg for systolic BP (SBP) and 6 mm Hg for diastolic BP (DBP). Correlation for mean SBP was 0.624 and for mean DBP was 0.491. The bias for oscillometric BP measurement was 8.7 mm Hg for SBP (P < .01) and 5.7 mm Hg for DBP (P < .01). BP status classification agreement was 61% for SBP and 63% for DBP, with Kappa values of .31 for SBP and .20 for DBP.

CONCLUSIONS

Compared with auscultation, the oscillometric device significantly overestimated both SBP and DBP, leading to frequent misclassification of BP status.

Epidemiology of chronic kidney disease in children

In the past 30 years there have been major improvements in the care of children with chronic kidney disease (CKD). However, most of the available epidemiological data stem from end-stage renal disease (ESRD) registries and information on the earlier stages of pediatric CKD is still limited. The median reported incidence of renal replacement therapy (RRT) in children aged 0-19 years across the world in 2008 was 9 (range: 4-18) [corrected] per million of the age-related population). [corrected] The prevalence of RRT in 2008 ranged from 18 to 100 per million of the age-related population. Congenital disorders, including congenital anomalies of the kidney and urinary tract (CAKUT) and hereditary nephropathies, are responsible for about two thirds of all cases of CKD in developed countries, while acquired causes predominate in developing countries. Children with congenital disorders experience a slower progression of CKD than those with glomerulonephritis, resulting in a lower proportion of CAKUT in the ESRD population compared with less advanced stages of CKD. Most children with ESRD start on dialysis and then receive a transplant. While the survival rate of children with ERSD has improved, it remains about 30 times lower than that of healthy peers. Children now mainly die of cardiovascular causes and infection rather than from renal failure.

Hypertension and future cardiovascular health in pediatric end-stage renal disease patients

BACKGROUND

There are now numerous studies that have documented an increased risk of cardiovascular morbidity and mortality in young adults who had childhood-onset end-stage renal disease (ESRD). Since the number of such patients surviving to adulthood is increasing, strategies to reduce this risk are urgently needed.

METHODS

The various risk factors contributing to adult cardiovascular disease in this population will be reviewed, with an emphasis on hypertension and its control. Data demonstrating the prevalence of hypertension in childhood chronic kidney disease as well as the results of improved blood pressure control in ESRD will also be presented.

CONCLUSIONS

Hypertension is exceedingly common in pediatric ESRD patients and frequently poorly controlled. Efforts to improve blood pressure control in this patient population could potentially reduce future cardiovascular morbidity and mortality.

Ambulatory blood pressure monitoring in children: imperfect yet essential

There has been increasing emphasis on hypertension and early cardiovascular disease in the pediatric age group over the past decade as a result of various factors, including the obesity epidemic and publication of new clinical guidelines. A key component of identifying children and adolescents with definite or potential hypertension is proper blood pressure (BP) measurement. While ambulatory blood pressure monitoring (ABPM) offers the potential for improved detection of youths at increased cardiovascular risk, it has not been widely adopted. This commentary highlights the crucial role of ABPM in the context of current trends, while at the same time identifying the current barriers to more widespread application of this technique. Chief among these is the lack of a robust, universally applicable database of pediatric ABPM normative values. Even in the absence of ideal normative data, ABPM can and should be widely applied, and a potential algorithm for such an approach is presented.

Hypertension in pediatric patients with childhood-onset chronic kidney disease: much to be learned, more to be done

Pediatric patients with chronic kidney disease are increasingly recognized as being at increased risk of developing cardiovascular disease as adults. Numerous risk factors contribute, hypertension being one of the most identifiable and potentially modifiable. Despite this, numerous studies have demonstrated that hypertension is common and is frequently underrecognized and/or undertreated in this population. Greater efforts are needed to identify and effectively treat hypertension in these vulnerable patients to reduce the future burden of adult cardiovascular disease.

Serum adiponectin complexes and cardiovascular risk in children with chronic kidney disease

In contrast to the general population, patients with chronic kidney disease (CKD) experience increased total adiponectin levels despite an increased prevalence of cardiovascular disease. Adiponectin circulates as trimer, low molecular weight (LMW), and high molecular weight (HMW) complexes. The distribution and role of each subfraction in CKD is unknown. This cross-sectional analysis examined the association of serum adiponectin and its subfractions with known cardiovascular risk factors in 105 children (median age 12 years; 56% male) enrolled into the Chronic Kidney Disease in Children (CKiD) study, an observational cohort study of children with CKD stage 2-4.HMW accounted for 46% of total adiponectin, followed by LMW (34%) and trimer (20%). In multivariable analysis, LMW was independently associated with iohexol glomerular filtration rate (GFR) (p = 0.004) and was higher in pubertal versus prepubertal children (p = 0.005). HMW/LMW ratio was independently associated with age and iohexol GFR (all p < 0.001). Unexpectedly, systolic blood pressure was positively correlated with HMW (p = 0.01), and HMW/LMW ratio (p = 0.007) and inversely correlated with LMW (p = 0.009). Among subfractions, only LMW was significantly correlated with left ventricular mass (LVM) index (p = 0.05). In multivariable analysis, decreased LMW was independently associated with higher LVM index [β= -0.25, 95% confidence interval (CI) -0.50, -0.03, p=0.04) after adjustment for body mass index (BMI), age, and blood pressure.The higher total adiponectin levels in children with CKD are associated with higher HMW and lower LMW. This imbalance may be an important biomarker for increased cardiovascular risk despite higher levels of total adiponectin in children with CKD.

Prevalence and correlates of multiple cardiovascular risk factors in children with chronic kidney disease

BACKGROUND AND OBJECTIVES

Although prevalence of traditional cardiovascular risk factors (CVRF) has been described in children with CKD, the frequency with which these CVRF occur concomitantly and the clinical characteristics associated with multiple CVRF are unknown. This study determined the prevalence and characteristics of multiple CVRF in children in the Chronic Kidney Disease in Children study.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using cross-sectional data from first follow-up visits, we determined the prevalence of four CVRF: hypertension (casual BP >95(th) percentile or self-reported hypertension with concurrent use of anti-hypertensive medication), dyslipidemia (triglycerides >130 mg/dl, HDL <40 mg/dl, non-HDL >160 mg/dl, or use of lipid-lowering medication), obesity (BMI >95(th) percentile), and abnormal glucose metabolism (fasting glucose >110 mg/dl, insulin >20 μIU/ml, or HOMA-IR >2.20, >3.61, or >3.64 for those at Tanner stage 1, 2 to 3, or 4 to 5, respectively) in 250 children (median age 12.2 years, 74% Caucasian, median iohexol-based GFR 45.2 ml/min per 1.73 m(2)).

RESULTS

Forty-six percent had hypertension, 44% had dyslipidemia, 15% were obese, and 21% had abnormal glucose metabolism. Thirty-nine percent, 22%, and 13% had one, two, and three or more CVRF, respectively. In multivariate ordinal logistic regression analysis, glomerular disease and nephrotic-range proteinuria were associated with 1.96 (95% confidence interval, 1.04 to 3.72) and 2.04 (95% confidence interval, 0.94 to 4.43) higher odds of having more CVRF, respectively.

CONCLUSIONS

We found high prevalence of multiple CVRF in children with mild to moderate CKD. Children with glomerular disease may be at higher risk for future cardiovascular events.

Methods for characterizing differences in longitudinal glomerular filtration rate changes between children with glomerular chronic kidney disease and those with nonglomerular chronic kidney disease

The rate of decline of glomerular filtration rate (GFR) in children with chronic kidney disease (CKD) can vary, even among those with similar diagnoses. Classic regression methods applied to the log-transformed GFR (i.e., lognormal) quantify only rigid shifts in a given outcome. The generalized gamma distribution offers an alternative approach for characterizing the heterogeneity of effect of an exposure on a positive, continuous outcome. Using directly measured GFR longitudinally assessed between 2005 and 2010 in 529 children enrolled in the Chronic Kidney Disease in Children Study, the authors characterized the effect of glomerular CKD versus nonglomerular CKD diagnoses on the outcome, measured as the annualized GFR ratio. Relative percentiles were used to characterize the heterogeneity of effect of CKD diagnosis across the distribution of the outcome. The rigid shift assumed by the classic mixed models failed to capture the fact that the greatest difference between the glomerular and nonglomerular diagnosis' annualized GFR ratios was in children who exhibited the fastest GFR declines. Although this difference was enhanced in children with an initial GFR level of 45 mL/minute/1.73 m(2) or less, the effect of diagnosis on outcome was not significantly modified by level. Generalized gamma models captured heterogeneity of effect more richly and provided a better fit to the data than did conventional lognormal models.

Hypertension and CKD

Hypertension is found in more than 50% of pediatric patients with CKD. However, its prevalence varies according to the cause of CKD. It is relatively infrequent in children with structural disorders. Acquired renal disorders are associated with an increased prevalence of hypertension, similar to that of adults. Recent studies using ambulatory blood pressure monitoring indicate that children with CKD also have a high prevalence of masked hypertension. Similar to adults, long-standing and uncontrolled hypertension in children is associated with the progression of CKD and development of end-organ damage including early cardiomyopathy and premature atherosclerosis. Aggressive treatment of hypertension should be an essential part of pediatric CKD care, not just to prevent the development of symptomatic cardiovascular disease but also to delay progression of CKD. Recent findings from the European Effect of Strict Blood Pressure Control and ACE Inhibition on Progression of Chronic Renal Failure in Pediatric Patients (ESCAPE) trial have shown that the aggressive treatment of blood pressure, to below the 50th percentile, has even greater benefit in children with CKD, unlike results seen in adult studies.

Insights from the Chronic Kidney Disease in Children (CKiD) study

Over the last 5 years, the Chronic Kidney Disease in Children (CKiD) prospective cohort study has enrolled close to 600 children ages 1 to 16 years with mild to moderate chronic kidney disease (CKD). The main purpose of this interim report is to review the initial cross-sectional data and conclusions derived from the clinical studies conducted within CKiD in the context of findings from other pediatric CKD and end-stage renal disease (ESRD) registry and cohort studies. In particular, special emphasis was placed on studying four aspects of chronic kidney disease in children, including the identification of risk factors related to disease progression, the impact of CKD on neurocognition and quality of life (QoL), the cardiovascular morbidity associated with CKD, and identifying the causes and effects of growth failure in the context of mild to moderate kidney failure.

Casual blood pressure and neurocognitive function in children with chronic kidney disease: a report of the children with chronic kidney disease cohort study

BACKGROUND AND OBJECTIVES

Children with chronic kidney disease (CKD) are at risk for cognitive dysfunction, and over half have hypertension. Data on the potential contribution of hypertension to CKD-associated neurocognitive deficits in children are limited. Our objective was to determine whether children with CKD and elevated BP (EBP) had decreased performance on neurocognitive testing compared with children with CKD and normal BP.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a cross-sectional analysis of the relation between auscultatory BP and neurocognitive test performance in children 6 to 17 years enrolled in the Chronic Kidney Disease in Children (CKiD) project.

RESULTS

Of 383 subjects, 132 (34%) had EBP (systolic BP and/or diastolic BP ≥90(th) percentile). Subjects with EBP had lower mean (SD) scores on Wechsler Abbreviated Scales of Intelligence (WASI) Performance IQ than those with normal BP (normal BP versus EBP, 96.1 (16.7) versus 92.4 (14.9), P = 0.03) and WASI Full Scale IQ (97.0 (16.2) versus 93.4 (16.5), P = 0.04). BP index (subject's BP/95(th) percentile BP) correlated inversely with Performance IQ score (systolic, r = -0.13, P = 0.01; diastolic, r = -0.19, P < 0.001). On multivariate analysis, the association between lower Performance IQ score and increased BP remained significant after controlling for demographic and disease-related variables (EBP, β = -3.7, 95% confidence interval [CI]: -7.3 to -0.06; systolic BP index, β = -1.16 to 95% CI: -2.1, -0.21; diastolic BP index, β = -1.17, 95% CI: -1.8 to -0.55).

CONCLUSIONS

Higher BP was independently associated with decreased WASI Performance IQ scores in children with mild-to-moderate CKD.

Effectiveness and safety of valsartan in children aged 6 to 16 years with hypertension

The effectiveness and safety of valsartan have not been assessed in hypertensive children. Therefore, hypertensive patients aged 6 to 16 years (n=261) were randomized to receive weight-stratified low- (10/20 mg), medium- (40/80 mg), or high-dose (80/160 mg) valsartan for 2 weeks. After 2 weeks, patients were randomized to a 2-week placebo-controlled withdrawal phase. Dose-dependent reductions in sitting systolic blood pressure (SSBP) and sitting diastolic blood pressure (SDBP) were observed after 2 weeks (low dose, -7.9/-4.6 mm Hg; medium dose, -9.6/-5.8 mm Hg; high dose, -11.5/-7.4 mm Hg [P<.0001 for all groups]). During the withdrawal phase, SSBP and SDBP were both lower in the pooled valsartan group than in the pooled placebo group (SSBP, -2.7 mm Hg [P=.0368]; SDBP, -3.0 mm Hg [P=.0047]). Similar efficacy was observed in all subgroups. Valsartan was well tolerated and headache was the most commonly observed adverse event during both the double-blind and 52-week open-label phases.

Clinical utility of valsartan in the treatment of hypertension in children and adolescents

Valsartan is a potent antagonist of the type 1 angiotensin receptor (AT(1)). By blocking the actions of angiotensin II on the AT(1), it inhibits vasoconstriction and synthesis of aldosterone thus lowering systemic blood pressure. Valsartan has been approved by the FDA for the treatment of hypertension in children aged 6 years and older. Valsartan can be dosed once a day with a sustained 24-hour effect on blood pressure reduction. The starting dose recommended in children is 1.3 mg/kg once daily (maximum 40 mg) which needs adjustment according to blood pressure response (dose range 1.3-2.7 mg/kg daily; up to 160 mg). A suspension form (4 mg/mL) is available for children who cannot swallow tablets. In patients aged 6 to 16 years, valsartan treatment (from a low dose of 10-20 mg to a high dose of 80-160 mg) resulted in dose-dependent reductions of 7.9-11.5 mmHg in systolic blood pressure and 4.6-7.4 mmHg in diastolic blood pressure. In 1- to 5-year-olds, valsartan (from a low dose of 5-10 mg to a high dose of 40-80 mg) reduced the systolic blood pressure by 8.4-8.6 mmHg and the diastolic blood pressure by 5.5 mmHg. Similar to adults and other antihypertensive medications, the most frequent side effect in children subsequent to valsartan use is headache. Current studies have not shown adverse effects on linear growth, weight gain, head growth, or development in children aged 1 to 5 years subsequent to valsartan use. Based on limited pediatric data, valsartan appears to be well tolerated and efficacious in reducing elevated blood pressure.

Preliminary findings of serum creatinine and estimated glomerular filtration rate (eGFR) in adolescents with intellectual disabilities

The present study aimed to describe the kidney function profile - serum creatinine and estimated glomerular filtration rate (eGFR), and to examine the relationships of predisposing factors to abnormal serum creatinine in people with intellectual disabilities (ID). Data were collected by a cross-sectional study of 827 aged 15-18 years adolescents with ID who participated in annual health examinations as they enrolled into special education schools in Taiwan. We used serum samples to determine participants' creatinine profiles, and the Cockcroft-Gault formula to calculate the data of eGFR to present the chronic kidney disease. The results found 22% of the participants have abnormal serum creatinine value (creatinine>1.0mg/dl) and 59.6%, 36.4% and 4.0% at chronic kidney disease (CKD) stage 1, 2 and 3 cases accordingly based on the Cockcroft-Gault formula. No CKD stage 4 and 5 cases in this study. That is, there were 4% CKD cases (eGFR <60 mL/min/1.73 m(2); CKD stage 3, 4 and 5) in adolescents with ID in this study. The results also indicated that gender and BMI could significantly predict abnormal creatinine condition in multivariate logistic regression analysis. Those boys with ID were more likely to have abnormal creatinine value than girls with ID (OR=10.13, 95% CI=5.96-17.23). In term of BMI, those underweight adolescents with ID were less likely to have high creatinine value compared to normal weight group (OR=0.45, 95% CI=0.28-0.72). In summary, this study provides the preliminary information of creatinine and estimated GFR in people with ID; we suggest the public health policy should initiate appropriate management strategies to monitor kidney function and to improve treatment outcomes of chronic kidney disease for this vulnerable population.

Longitudinal relations between obesity and hypertension following pediatric renal transplantation

Obesity and hypertension frequently complicate renal transplantation (RTxp). The objective was to assess relations among obesity, hypertension, and glucocorticoids in pediatric RTxp recipients. A retrospective cohort study was carried out in 141 RTxp recipients, 2-21 years of age, with >or=12 months of follow-up. Body mass index Z-score (BMI-Z), systolic and diastolic blood pressure Z-scores (SBP-Z and DBP-Z), and medications at 1, 3, 6, and 12 months and annually thereafter were recorded. Quasi-least squares regression analysis was used. The prevalence of obesity (BMI>or=95th percentile) increased from 13% at baseline to >30% from 3 months onward. Greater glucocorticoid exposure (mg/kg/day) was associated with greater increases in BMI-Z (p<0.001). This association was greater in males, younger recipients, and those with lower baseline BMI-Z (all interactions p<0.02). The prevalence of systolic hypertension (SBP>or=95th percentile) was 73% at 1 month and >or=40% at all follow-up visits. Greater glucocorticoid exposure (p<0.001) and increases in BMI-Z (p=0.005) were independent determinants of SBP-Z over time. Cyclosporine (versus tacrolimus) was independently associated with greater SBP-Z and DBP-Z (p=0.001). Sustained obesity and hypertension frequently complicated pediatric RTxp. Obesity was an independent determinant of systolic hypertension. Strategies are needed to prevent obesity and its impact on hypertension, cardiovascular disease, and allograft survival.

Pediatric hypertension update

PURPOSE OF REVIEW

The field of childhood hypertension has been changing rapidly since publication of the most recent consensus guidelines contained in the 2004 'Fourth Report'.

RECENT FINDINGS

Several epidemiologic studies have indicated that the prevalence of hypertension in children and adolescents is on the increase. A major factor behind this increase is the childhood obesity epidemic. There is substantial new information on the frequency of hypertensive target-organ damage in the young, including vascular, cardiac and renal effects. These data have led some authorities to recommend changes in how hypertension is evaluated and managed in the young.

SUMMARY

There has been significant new knowledge gained about many aspects of childhood hypertension over the past 5 years. Clinicians who care for children and adolescents with high blood pressure should familiarize themselves with these new data and incorporate them into their clinical decision-making.

Early origins of cardiovascular disease in pediatric chronic kidney disease

The importance of cardiovascular disease in adults with chronic kidney disease is now well recognized. For children who develop chronic kidney disease, cardiovascular disease is also a leading cause of eventual morbidity and mortality. Although the clinical manifestations of cardiovascular disease may not be apparent until later, early subclinical findings can be observed even during childhood. This review updates the reader on the epidemiology of cardiovascular disease in pediatric chronic kidney disease, discusses risk factors and potential mechanisms of accelerated cardiovascular disease, reviews evidence of early manifestations of cardiovascular disease in pediatric chronic kidney disease, and briefly discusses prevention and treatment strategies.

A double-blind, dose-response study of the efficacy and safety of olmesartan medoxomil in children and adolescents with hypertension

The current study investigated the efficacy and safety of olmesartan medoxomil in children with hypertension, defined as systolic blood pressure measured at or above the 95th percentile (90th percentile for patients with diabetes, glomerular kidney disease, or family history of hypertension) for age, gender, and height while off any antihypertensive medication. The active treatment phase was conducted in 2 periods, with 2 cohorts in each period (cohort A, 62% white; cohort B, 100% Black). In period 1, patients stratified by weight received low-dose (2.5 or 5 mg) or high-dose (20 or 40 mg) olmesartan medoxomil daily for 3 weeks. In period 2, patients maintained their olmesartan medoxomil dose or initiated placebo washout for an additional 2 weeks. Period 1 efficacy results showed a dose-dependent, statistically significant reduction in seated trough systolic and diastolic blood pressure for both cohorts, with mean blood pressure reductions numerically smaller in cohort B than in cohort A. The olmesartan medoxomil dose response remained statistically significant when adjusted for body weight. In period 2, blood pressure control decreased in those patients switching to placebo, whereas patients continuing to receive olmesartan medoxomil therapy maintained consistent blood pressure reduction. Adverse events were generally mild and unrelated to study medication. Olmesartan medoxomil was safe and efficacious in children with hypertension, resulting in significant blood pressure reductions.

Risk factors for progression of chronic kidney disease

PURPOSE OF REVIEW

The present review provides an overview of the identified risk factors for chronic kidney disease (CKD) progression emphasizing the pediatric population.

RECENT FINDINGS

Over the past 10 years, there have been significant changes to our understanding and study of preterminal kidney failure. Recent refinements in the measurement of glomerular filtration rate and glomerular filtration rate estimating equations are important tools for identification and association of risk factors for CKD progression in children. In pediatric CKD, lower level of kidney function at presentation, higher levels of proteinuria, and hypertension are known markers for a more rapid decline in glomerular filtration rate. Anemia and other reported risk factors from the pregenomic era require further study and validation. Genome-wide association studies have identified genetic loci that have provided novel genetic risk factors for CKD progression.

SUMMARY

With cohort studies of children with CKD becoming mature, they have started to yield important refinements to the assessment of CKD progression. Although many of the traditional risk factors for renal progression will certainly be assessed, such cohorts will be important for evaluating novel risk factors identified by genome-wide studies.

Randomized, double-blind, controlled study of losartan in children with proteinuria

BACKGROUND AND OBJECTIVES

No large, randomized, double-blind trials in children with proteinuria treated with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers have previously been reported.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This 12-week, double-blind, multinational study investigated the effects of losartan 0.7 to 1.4 mg/kg per day compared with placebo (normotensive stratum) or amlodipine 0.1 to 0.2 mg/kg per day up to 5 mg/d (hypertensive stratum) on proteinuria (morning-void urinary protein-creatinine ratio, baseline > or =0.3 g/g) in 306 children up to 17 years of age.

RESULTS

Twelve weeks of treatment with losartan significantly reduced proteinuria compared with amlodipine/placebo: losartan -35.8% (95% confidence interval: -27.6% to -43.1%) versus amlodipine/placebo 1.4% (95% confidence interval: -10.3% to 14.5%), P < or = 0.001. Significance remained after adjustment for differences across treatment groups in change in BP (losartan produced incremental systolic and diastolic BP reductions versus amlodipine of 5.4 and 4.6 mmHg, respectively; and versus placebo of 3.8 and 4.0 mmHg, respectively). Proteinuria reduction was consistently observed in the normotensive (-34.4% losartan; 2.6% placebo) and hypertensive (-41.5% losartan; 2.4% amlodipine) strata, and in all prespecified subgroups, including age, gender, race, Tanner stage, weight, prior therapy with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, as well as among the most common etiologies of proteinuria. Adverse event incidence was low and comparable in all groups.

CONCLUSIONS

Losartan significantly lowered proteinuria and was well tolerated after 12 weeks in children aged 1 to 17 years with proteinuria with or without hypertension, a population that has not previously been rigorously studied.

Masked hypertension associates with left ventricular hypertrophy in children with CKD

Left ventricular hypertrophy (LVH) associates with increased risk for cardiovascular disease. Hypertension leads to LVH in adults, but its role in the pathogenesis of LVH in children is not as well established. To examine left ventricular mass and evaluate factors associated with LVH in children with stages 2 through 4 chronic kidney disease (CKD), we analyzed cross-sectional data from children who had baseline echocardiography (n = 366) and underwent ambulatory BP monitoring (n = 226) as a part of the observational Chronic Kidney Disease in Children (CKiD) cohort study. At baseline, 17% of children had LVH (11% eccentric and 6% concentric) and 9% had concentric remodeling of the left ventricle. On the basis of a combination of ambulatory and casual BP assessment (n = 198), 38% of children had masked hypertension (normal casual but elevated ambulatory BP) and 18% had confirmed hypertension (both elevated casual and ambulatory BP). There was no significant association between LVH and kidney function. LVH was more common in children with either confirmed (34%) or masked (20%) hypertension compared with children with normal casual and ambulatory BP (8%). In multivariable analysis, masked (odds ratio 4.1) and confirmed (odds ratio 4.3) hypertension were the strongest independent predictors of LVH. In conclusion, casual BP measurements alone are insufficient to predict the presence of LVH in children with CKD. The high prevalence of masked hypertension and its association with LVH supports early echocardiography and ambulatory BP monitoring to evaluate cardiovascular risk in children with CKD.

Strict blood-pressure control and progression of renal failure in children

BACKGROUND

Although inhibition of the renin-angiotensin system delays the progression of renal failure in adults with chronic kidney disease, the blood-pressure target for optimal renal protection is controversial. We assessed the long-term renoprotective effect of intensified blood-pressure control among children who were receiving a fixed high dose of an angiotensin-converting-enzyme (ACE) inhibitor.

METHODS

After a 6-month run-in period, 385 children, 3 to 18 years of age, with chronic kidney disease (glomerular filtration rate of 15 to 80 ml per minute per 1.73 m(2) of body-surface area) received ramipril at a dose of 6 mg per square meter of body-surface area per day. Patients were randomly assigned to intensified blood-pressure control (with a target 24-hour mean arterial pressure below the 50th percentile) or conventional blood-pressure control (mean arterial pressure in the 50th to 95th percentile), achieved by the addition of antihypertensive therapy that does not target the renin-angiotensin system; patients were followed for 5 years. The primary end point was the time to a decline of 50% in the glomerular filtration rate or progression to end-stage renal disease. Secondary end points included changes in blood pressure, glomerular filtration rate, and urinary protein excretion.

RESULTS

A total of 29.9% of the patients in the group that received intensified blood-pressure control reached the primary end point, as assessed by means of a Kaplan-Meier analysis, as compared with 41.7% in the group that received conventional blood-pressure control (hazard ratio, 0.65; confidence interval, 0.44 to 0.94; P=0.02). The two groups did not differ significantly with respect to the type or incidence of adverse events or the cumulative rates of withdrawal from the study (28.0% vs. 26.5%). Proteinuria gradually rebounded during ongoing ACE inhibition after an initial 50% decrease, despite persistently good blood-pressure control. Achievement of blood-pressure targets and a decrease in proteinuria were significant independent predictors of delayed progression of renal disease.

CONCLUSIONS

Intensified blood-pressure control, with target 24-hour blood-pressure levels in the low range of normal, confers a substantial benefit with respect to renal function among children with chronic kidney disease. Reappearance of proteinuria after initial successful pharmacologic blood-pressure control is common among children who are receiving long-term ACE inhibition. (ClinicalTrials.gov number, NCT00221845.)

Hypertension in pediatric long-term hemodialysis patients in the United States

BACKGROUND AND OBJECTIVES

Data are limited regarding BP distribution and the prevalence of hypertension in pediatric long-term dialysis patients. This study aimed to examine BP distribution in U.S. pediatric long-term hemodialysis patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This cross-sectional study of all U.S. pediatric (aged 0-< 18 yr, n = 624) long-term hemodialysis patients was performed as part of the Centers for Medicare & Medicaid Services End-Stage Renal Disease (ESRD) Clinical Performance Measures Project. BP and clinical information were collected monthly in October, November, and December 2001. Hypertension was defined as the mean of pre- and postdialysis systolic or diastolic BP above the 95th percentile for age, height, and sex, or antihypertensive medication use. Results were calculated by age, sex, race, ethnicity, ESRD duration, body mass index percentile, primary cause of ESRD, and laboratory data.

RESULTS

Hypertension was present in 79% of patients; 62% used antihypertensive medication. Five percent of patients were prehypertensive (mean BP at 90th to 95th percentile). Hypertension was uncontrolled in 74% of treated patients. Characteristics associated with hypertension included acquired kidney disease, shorter duration of ESRD, and lower mean hemoglobin and calcium values. Characteristics associated with uncontrolled hypertension were younger age and shorter duration of ESRD.

CONCLUSIONS

Hypertension is common in U.S. pediatric long-term hemodialysis patients, uncontrolled in 74% of treated patients, and untreated in 21% of hypertensive patients. It is concluded that a more aggressive approach to treatment of hypertension is warranted in pediatric long-term hemodialysis patients.

Cardiovascular disease in CKD in children: update on risk factors, risk assessment, and management

In young adults with onset of chronic kidney disease in childhood, cardiovascular disease is the most common cause of death. The likely reason for increased cardiovascular disease in these patients is a high prevalence of traditional and uremia-related cardiovascular disease risk factors during childhood chronic kidney disease. Early markers of cardiomyopathy, such as left ventricular hypertrophy and left ventricular dysfunction, and early markers of atherosclerosis, such as increased carotid artery intima-media thickness, carotid arterial wall stiffness, and coronary artery calcification, frequently are found in this patient population. The purpose of this review is to provide an update of recent advances in the understanding and management of cardiovascular disease risks in this population.

Current advances in chronic kidney disease in children: growth, cardiovascular, and neurocognitive risk factors

Linear growth and neurocognitive development are two of the most important differences between adults and children, in terms of clinical issues that must be addressed in patients with chronic kidney disease (CKD). Correction of metabolic acidosis, nutritional deficiency, and renal osteodystrophy improve linear growth, but many children require administration of growth hormone to achieve normal growth. A variety of neurocognitive deficits occur in children with CKD, although there has been an improvement in outcome via improved dialysis, correction of malnutrition, and decreased aluminum exposure. Although growth and neurocognitive development are delayed, cardiovascular complications are accelerated in children with CKD, and are reflected in a dramatic increase in cardiovascular mortality compared with healthy children. Other early cardiovascular complications in children with CKD include left ventricular hypertrophy, cardiac dysfunction, and vascular calcifications.

Cardiovascular disease in children with CKD or ESRD

Cardiovascular disease accounts for 40% of all deaths among pediatric patients with end-stage renal disease (ESRD). ESRD has a particularly large influence on the cardiovascular system in children, as indicated by the more than 700-fold increased risk of cardiac death in affected individuals compared with healthy children of the same age. The prevalence of ESRD is low in children, however, and, consequently, few cardiac deaths occur. As a result, prospective follow-up studies of cardiac risk factors in the pediatric setting are lacking. Nevertheless, cross-sectional data on cardiac disease in children with ESRD have started to emerge. Arterial medial calcification is more prominent in children than classic atherosclerotic intimal calcification. Current data suggest that endothelial dysfunction appears early in renal failure in children, and is followed by arterial medial calcification. This calcification causes arterial wall stiffening and subsequently left ventricular hypertrophy. High systolic blood pressure and serum concentrations of intact parathyroid hormone, calcium and phosphate, as well as long-term dialysis, seem to be important risk factors for cardiovascular disease in pediatric patients with ESRD. These features are important targets for preventive intervention. This Review summarizes the currently available data on cardiovascular disease in children with renal failure.