Screening for eligibility in the study of antihypertensive medication in children: experience from the Ziac Pediatric Hypertension Study

Blood Pressure in Children in the 21st Century: What Do We Know and Where Do We Go From Here?

The association between hypertension in adulthood and cardiovascular morbidity and death is well known. Based on that association, a diagnosis of elevated blood pressure in children has been clinically interpreted as early cardiovascular disease. The objective of this review is to discuss historical data and new research on the relationship between elevated blood pressure and early preclinical and later adult cardiovascular disease. After summarizing the evidence, we will address the gaps in knowledge around Pediatric hypertension in an effort to stimulate research into the important role that control of blood pressure in youth may play in preventing adult cardiovascular disease.

Burden of Hypertension and Abnormal Glomerular Permeability in Hypertensive School Children

Background

Childhood hypertension has been associated with target-organ damage in young adults. It is often asymptomatic in both children and adolescents; when persistent, and long-standing, it could be a significant risk factor for kidney damage and increased glomerular permeability.

Objectives

Burden of hypertension and its impact on glomerular permeability were prospectively determined in randomly recruited primary school children.

Patients and Methods

Blood pressure (BP) measurement was performed by the auscultation method, and abnormal glomerular permeability was assessed by dipstick testing of urine for persistent proteinuria and/or hematuria for ≥ three months in hypertensive children.

Results

Of 1,335 pupils aged 10.0 ± 2.4 (6.0 - 14.0) years, 33 (2.5%) were hypertensive. Overall mean systolic/diastolic BP was 125.6 ± 6.5/81.7 ± 3.3 (range: 114.0 - 140.0/80.0 - 90.0) mmHg. Nine (27.3%) had combined systolic and diastolic hypertension, 126.7 ± 5.7/80.0 - 80.0 ± 0.0 (120.0 - 130.0/80.0 - 80.0) mmHg. Isolated systolic hypertension, 125.4 ± 6.7 (114.0 - 140.0) mmHg, was present in 14 (42.4%), whereas 10 (30.3%) had isolated diastolic hypertension, 82.0 ± 3.5 (80.0 - 90.0) mmHg. Mean systolic and diastolic BP were 131.0 ± 3.3 (130.0 - 140.0) mmHg and 86.5 ± 4.43 (80.0 - 90.0) mmHg, respectively. According to the dipstick test, none of the hypertensive pupils showed urinalysis evidence of proteinuria and/or hematuria after three months of testing.

Conclusions

Although the burden of hypertension was 2.5%, the dipstick method did not detect any hypertension-related abnormal glomerular permeability in the school children.

Effect of placebo on ambulatory blood pressure monitoring in children

BACKGROUND

Ambulatory blood pressure monitoring (ABPM) has been proposed as a useful tool for more accurately diagnosing hypertension (HTN) and evaluating blood pressure (BP) response in pediatric anti-hypertensive trials. ABPM captures multiple BP measurements during routine daily activities and is thus an excellent method for identifying white-coat HTN. Additionally, ABPM measurements in adults do not demonstrate the placebo effect commonly seen with casual BP measurements, although this has yet to be evaluated in children. Therefore,, the aim of this study was to assess the effect of placebo on ABPM measurements in children.

METHODS

A total of 141 children aged 5-16 years with elevated BP were randomized into a multi-center, single-blind, cross-over trial. Subjects received a placebo pill prior to wearing a 24-h ABPM device at one of two visits separated by 1-2 weeks. Study procedures were otherwise identical at both visits.

RESULTS

Mean systolic and diastolic BP for all measured time periods were similar between visits, as was the number of children diagnosed with HTN at each visit.

CONCLUSION

Having confirmed HTN at baseline did not affect the impact of placebo on mean BP. If confirmed, this lack of placebo effect on ABPM measurements may allow for the design of direct comparison pediatric anti-hypertensive trials without a placebo arm.

Long-term indapamide retard therapy in adolescents with Stage I arterial hypertension

Aim. To study the dynamics of office blood pressure (BP) levels, autonomic balance, endothelial dysfunction, and vascular remodelling in adolescents with Stage I arterial hypertension (AH), treated with indapamide retard (IR). Material and methods. In total, the study included 41 adolescent boys, aged 16-18 years, with Stage I AH (main group, MG), and 27 healthy adolescents (control group, CG). The MG participants received, IR (1,5 mg/day) for 6 months. At baseline and in the end of the study, all participants underwent office BP measurement, echocardiography, veloergometry, and the assessment of heart rate variability (HRV), endothelial dysfunction (reactive hyperemia test, endotelin-1 levels), microalbuminuria (MAU), and vascular parameters, such as large artery rigidity and intima-media thickness. Results. Target BP levels were achieved in all MG patients by Week 4 of the treatment, with normal BP values registered throughout the follow-up period. Indapamide therapy was associated with decreased hemodynamic cardiovascular load, normalized endothelial function, and MAU disappearance. IR monotherapy had beneficial effects on HRV, due to moderate parasympathetic stimulation. Conclusion. IR is an effective and safe medication for long-term treatment of adolescents with Stage I AH.

Obesity hypertension in adolescents: epidemiology, evaluation, and management

The prevalence of hypertension among all adolescents is approximately 3.5%, with somewhat higher rates of prehypertension. Obesity affects approximately 20% of adolescents in the United States, and the prevalence of hypertension is much higher among obese adolescents compared with nonobese adolescents. As in other populations, the evaluation of elevated blood pressure in obese adolescents should begin with a confirmation of the blood pressure elevation, followed by a focused diagnostic work-up to detect possible secondary causes of hypertension. Primary therapy for obesity-related hypertension in adolescents begins with weight loss, and may include antihypertensive medications if target-organ damage or other indications for drug therapy are present. The emphasis of management should be reduction of future cardiovascular risk.

Concepts guiding therapy for hypertension in children

Increasing attention has been focused on identifying children with prehypertension and hypertension (HTN). Obesity and low birthweight are two risk factors that predispose children to develop HTN during their childhood years or later as adults. Early onset of pre-HTN and HTN increases the lifetime risk for cardiovascular sequelae. Lifestyle modification should be part of the initial recommendations for management of all hypertensive children. In those children requiring pharmacologic therapy, the choice of medication should be guided by the etiology of HTN, the needs of the child and the risk and benefit profiles of the various drug classes. The long-term impact of antihypertensive therapy in children is not known. Concerns regarding the effects of HTN and its treatment on cognitive function are of particular importance in the growing child and warrant further study. Ongoing investigations that offer promise for innovative therapeutic approaches in the future are discussed.

Waist circumference and fat intake are associated with high blood pressure in Mexican children aged 8 to 10 years

BACKGROUND

Elevated blood pressure at a young age is a predictor of blood pressure elevation later in life and has been associated with being overweight. However, it seems that there are other factors related to hypertension in childhood.

OBJECTIVE

To determine the anthropometric, physical activity, and dietary factors associated with both systolic and diastolic hypertension in a group of Mexican school-aged children.

DESIGN

In this cross-sectional descriptive study, blood pressure, anthropometrics, physical activity, and dietary intake (assessed with a multiple-pass 24-hour dietary recall) evaluations were performed on school-aged children from September 2005 to July 2006.

SUBJECTS

Children aged 8 to 10 years (626 boys and 613 girls) from a convenience sample of 23 public schools of low socioeconomic status in Mexico City were included. Systolic and diastolic hypertension were defined as blood pressure > or = 95th percentile for age, sex, and height, without diastolic or systolic prehypertension or hypertension, respectively. Mixed hypertension was defined as the presence of both systolic and diastolic hypertension.

STATISTICAL ANALYSIS

Descriptive statistics, chi(2) tests, analysis of variance, post hoc analysis with Bonferroni method, and logistic regression analysis were performed. Continuous variables are presented as mean+/-standard deviation, categorical variables as percentages, and the association measures as adjusted odds ratios (ORs). A P value < 0.05 was considered statistically significant, and 95% confidence intervals were calculated for adjusted ORs.

RESULTS

The dietary intake analysis showed that both boys and girls had low fiber intake (< 25 g/day) as well as an excessive mean consumption of total and saturated fat (> 35% and > 10% of daily energy, respectively). From the total group of children, 3.6% had systolic hypertension, 14.2% diastolic hypertension, and 22.8% mixed hypertension. The higher values of weight, body mass index, waist circumference, and prevalence of overweight and obesity were more commonly seen among children with mixed hypertension, followed by children in the systolic group. Subjects with diastolic and mixed hypertension had an elevated intake of dietary total fat (37.7% and 38.2% of daily energy intake, respectively). Moreover, an adjusted OR of 1.06 (95% confidence interval 1.01 to 1.11) for systolic hypertension per increase of 1 cm in waist diameter was found and total fat intake > 35% of the daily energy showed an adjusted OR of 2.61 (95% confidence interval 1.27 to 5.36) for diastolic hypertension.

CONCLUSIONS

In a sample of Mexican children of low socioeconomic status, the prevalence of hypertension was high. Waist circumference was the main factor associated with systolic hypertension, and higher intake of total fat was related to diastolic hypertension.

[Hypertension in obese children and adolescents]

Obesity, especially upper body fat distribution, has become an increasingly important medical problem in children and adolescents. Outcomes related to childhood obesity include, as in adult population, hypertension, type 2 diabetes mellitus, dyslipidemia, left ventricular hypertrophy, obstructive sleep apnea, orthopedic and socio-psychological problems. Obese children are at approximately 3-fold higher risk for hypertension from non-obese ones. Obesity-hypertension appears to be characterized by a preponderance of isolated systolic hypertension, increased heart rate and blood pressure variability, increased levels of plasma catecholamine and aldosterone, and salt-sensitivity. Lifestyle changes of weight loss, healthier diet and regular physical exercise are effective in obesity-hypertension control, though pharmacological treatment is frequently necessary. Screening for dyslipidemia and impaired glucose tolerance should be performed in paediatric patients with obese hypertension on regular basis, at least once annually or semiannually to discover metabolic syndrome and to prevent its increased cardiovascular risk. Of course, prevention of obesity is the primary goal.

Home and office blood pressure in children and adolescents: the role of obesity. The Arsakeion School Study

Obesity is related to office blood pressure (OBP). Important discrepancies exist between OBP and home blood pressure (HBP), providing complementary information for the management of hypertension. The association between obesity and HBP has not been investigated in children. The evidence on the role of obesity in the predominance of systolic blood pressure (SBP) over diastolic (DBP) in paediatric hypertension is limited. A total of 778 healthy subjects aged 6-18 years were recruited in this study. OBP and HBP were measured using electronic devices validated in children. Anthropometric measurements were measured and expressed as z-scores for height or age. Among all indices of obesity (z-scores), body mass index (BMI) showed the best association with BP. The effect of obesity (BMI) was more pronounced on: (i) SBP than DBP and (ii) H-SBP than O-SBP (O-SBP: r2=0.09, O-DBP: r2=0.05, H-SBP: r2=0.12, H-DBP: r2=0.06). The prevalence of systolic hypertension was higher than that of diastolic hypertension. This difference was significant only in office readings and independent from obesity (normal weight: 6.3% systolic hypertension versus 1.2% diastolic; obese: 37.9% versus 6.9%, P<0.05 for both). These data imply that in children and adolescents the z-score of BMI is the most appropriate index of the association between BP and obesity. It also suggests that obesity is probably more closely associated with home than office BP. Finally, although obesity appears to affect SBP more than DBP, these results suggest that the predominance of systolic hypertension in children and adolescents might not be only related to obesity but also to the measurement setting (office).

High blood pressure and hypertension in children with newly diagnosed acute leukemia and lymphoma

Little has been published on the rate of prehypertension (HBP) and hypertension (HTN) in children with hematologic malignancies. This study was preformed to determine the prevalence and predictors of HBP and HTN in newly diagnosed acute leukemia and lymphoma patients. Retrospectively, blood pressure (BP) values were followed from admission until normalization in 102 children. HBP and HTN were defined as either a systolic or diastolic value > or = the 90th and 95th percentile BP measurement, respectively. HBP and HTN were identified in 68.6% and 52.9% of children prior to chemotherapy and 78.4% and 67.3% postchemotherapy, respectively. Mean time to BP normalization was 54 days. Only ten children (15% of HTN patients) received antihypertensive therapy. Logistic regression determined that the only predictor for HBP and HTN was the estimated glomerular filtration rate (eGFR) at the time of admission -- every 10 ml/min per 1.73 m(2) increase led to a 16% and 14% decrease in the odds of postchemotherapy HBP (p = 0.02) and HTN (p = 0.03), respectively. A surprisingly high prevalence of BP abnormalities was identified and lower eGFR predicted HBP and HTN in children with newly diagnosed hematologic malignancies. Better recognition and serious consideration for treatment should be given to this cardiovascular abnormality.

Pediatric antihypertensive trial failures: analysis of end points and dose range

Historically, drugs prescribed for children have not been studied in pediatric populations. Since 1997, however, a 6-month extension of marketing rights is granted if manufacturers conduct Food and Drug Administration-defined pediatric trials. In nearly half of the drugs studied, there were unexpected results in dosing, safety, or efficacy compared with adult studies, including failure of half of the antihypertensive dose-response trials, which are pivotal for deriving dosing recommendations. We sought to define design elements that might have contributed to these trial failures by combining patient-level data from 6 dose-ranging antihypertensive efficacy trials completed for pediatric exclusivity and submitted to the Food and Drug Administration from 1998 to 2005. We evaluated dosing, primary end point, and other components to assess underlying reasons for failure to show efficacy in children. Of 6 trials examined, 3 showed a dose response; 3 did not. Eligibility criteria were similar across studies, as were subject demographics. Successful studies showed large differences in doses, with little or no overlap between low, medium, and high doses; failed trials used narrow dose ranges with considerable overlap. Successful trials also provided pediatric formulations and used reduction in diastolic, not systolic, blood pressure as the primary end point. Careful attention to pediatric pharmacology and selection of primary end points can improve trial performance. We found poor dose selection, lack of acknowledgement of differences between adult and pediatric populations, and lack of pediatric formulations to be associated with failures. More importantly, our ability to combine data across trials allowed us to evaluate and potentially improve trial design.

Overweight, ethnicity, and the prevalence of hypertension in school-aged children

OBJECTIVES

To describe the current prevalence of pediatric hypertension and the relationships between gender, ethnicity, overweight, and blood pressure.

METHODS

School-based screening was performed in 5102 children (13.5 +/- 1.7 years) from May through November 2002. Age, gender, ethnicity, weight, and height were ascertained, and body mass index (BMI) was calculated as weight (kg)/height (m2). Overweight was defined as BMI > or =95th percentile. Students with blood pressure >95th percentile on the first screening underwent a second screening 1 to 2 weeks later, and then a third screening if blood pressure was >95th percentile at the second screening.

RESULTS

Ethnicity distribution was 44% white, 25% Hispanic, 22% African American, and 7% Asian. Overall, overweight prevalence was 20%, which varied significantly by ethnicity (31% Hispanic, 20% African American, 15% white, and 11% Asian). The prevalence of elevated blood pressure after first, second, and third screenings was 19.4%, 9.5%, and 4.5%, respectively. Elevated blood pressure on first screening was highest among Hispanics (25%) and lowest among Asians (14%). Ethnic differences in the prevalence of hypertension (elevated blood pressure on 3 screenings) were not significant after controlling for overweight. The prevalence of hypertension increased progressively as the BMI percentile increased from < or =5th percentile (2%) to > or =95th percentile (11%). After adjustment for gender, ethnicity, overweight, and age, the relative risk of hypertension was significant for gender (relative risk: 1.50; confidence interval: 1.15, 1.95) and overweight (relative risk: 3.26; confidence interval: 2.50, 4.24).

CONCLUSIONS

These results confirm an evolving epidemic of cardiovascular risk in youth, as evidenced by an increase in the prevalence of overweight and hypertension, notably among ethnic minority children.

Ethics of placebo use in pediatric clinical trials: the case of antihypertensive drug studies

Industry-sponsored pediatric clinical trials of antihypertensive medications have greatly increased in number since passage of the Food and Drug Modernization Act of 1997. This development should ultimately benefit the treatment of hypertensive children by increasing the amount of scientific knowledge regarding the efficacy and safety of antihypertensive agents in children. However, the designs of many of these trials raise ethical questions related to the inclusion of placebo controls, a practice that has largely been abandoned in trials of antihypertensives in adults because of the well-known adverse consequences of untreated hypertension. This is an especially important issue in pediatric hypertension, as many hypertensive children have either secondary forms of hypertension or hypertension-induced target organ damage, potentially increasing the risk of harm during exposure to placebo. Against this background, and with a strong emphasis on protection of this vulnerable patient population, a strict set of conditions for use of placebos in pediatric antihypertensive trials is proposed.

Clinical trial of extended-release felodipine in pediatric essential hypertension

Essential hypertension in pediatric patients may require pharmacological treatment. There is a need for efficacious, safe, and well-tolerated antihypertensive agents with a once-a-day dosing regimen in children and adolescents. The aim of the trial was to evaluate the dose-response and tolerability of the dihydropyridine calcium channel blocker, felodipine extended-release tablets (felodipine ER), given once daily to pediatric patients with essential hypertension. A randomized double-blind, parallel-group, multi-center clinical study comparing felodipine ER (2.5, 5, or 10 mg once daily) and placebo was performed on pediatric patients with a baseline systolic (SBP) or diastolic blood pressure (DBP) above the 95th percentile for age, sex, and height. Of 133 randomized patients, 128 (96.2%) completed the 3 weeks of double-blind treatment. The study population included 50% children 6-12 years of age or Tanner stage <or=3, 39% black, and 40% female patients. All doses of felodipine ER and placebo decreased both SBP and DBP. The 5-mg dose of felodipine ER resulted in a significant decline in trough sitting, standing, and supine DBP (placebo-adjusted, -4.6, -5.06, and -5.05 mmHg, respectively, P<0.05) compared with placebo. However, there was no significant decline in SBP. The 2.5- and 10-mg doses showed no significant differences compared with placebo in lowering BP. The effect of felodipine ER was comparable in patient subgroups by age, race, and gender. The drug was well tolerated. The study failed to show a dose response of felodipine ER in pediatric patients with essential hypertension. This finding might be explained in part by the limitations of study design. The spectrum of side effects in pediatric patients was comparable with that in adults, except for a lower incidence of peripheral edema. Further studies are needed to clarify the role of felodipine ER in the management of children and adolescents with essential hypertension.

Obesity hypertension in children: a problem of epidemic proportions

Obesity has become an increasingly important medical problem in children and adolescents. In national surveys from the 1960s to the 1990s, the prevalence of overweight in children grew from 5% to 11%. Outcomes related to childhood obesity include hypertension, type 2 diabetes mellitus, dyslipidemia, left ventricular hypertrophy, nonalcoholic steatohepatitis, obstructive sleep apnea, orthopedic problems, and psychosocial problems. Once considered rare, primary hypertension in children has become increasingly common in association with obesity and other risk factors, including a family history of hypertension and an ethnic predisposition to hypertensive disease. Obese children are at approximately a 3-fold higher risk for hypertension than nonobese children. In addition, the risk of hypertension in children increases across the entire range of body mass index (BMI) values and is not defined by a simple threshold effect. As in adults, a combination of factors including overactivity of the sympathetic nervous system (SNS), insulin resistance, and abnormalities in vascular structure and function may contribute to obesity-related hypertension in children. The benefits of weight loss for blood pressure reduction in children have been demonstrated in both observational and interventional studies. Obesity in childhood should be considered a chronic medical condition that is likely to require long-term management. Ultimately, prevention of obesity and its complications, including hypertension, is the goal.

Pediatric hypertension 2001

During the past decade, there has been a surge of interest in childhood and adolescent hypertension. The current review summarizes work published during the past year in the following areas: prenatal and early postnatal causes of hypertension; new information on the genetics of childhood hypertension; the relation of obesity, insulin resistance, and diabetes to hypertension; the use of ambulatory blood pressure monitoring to evaluate childhood hypertension; and advances in drug therapy for children with hypertension. The information obtained during the past year has improved our understanding of the pathogenesis, diagnosis, and treatment of childhood hypertension.

Isolated systolic hypertension, obesity, and hyperkinetic hemodynamic states in children

OBJECTIVE

To determine the factors that contribute to the pathogenesis of isolated systolic hypertension in children.

METHODS

School-based measurement was performed of blood pressure (BP), heart rate, weight, and height in 2460 students (49% Hispanic, 31% black, 13% white) 12 to 16 years of age in 8 urban public schools. An independent group of 71 untreated children underwent 24-hour ambulatory BP monitoring (ABPM) to confirm clinic hypertension and assess circadian BP patterns.

RESULTS

Hypertension and obesity were found in 17% and 23% of students, respectively. Among hypertensive students, 88% (363/413) had isolated systolic hypertension. Hypertension was more prevalent in obese than nonobese students (33% vs 11%, P <.0001). Obese hypertensive students had higher resting heart rate than nonobese normotensive patients (85.9 vs 79.6 beats/min, P <.001). Among patients who underwent ABPM, isolated systolic hypertension was found in 51% (36/71) by clinic BP and in 62% (18/29) with confirmed hypertension by ABPM. Blood pressure variability during daytime and sleep periods was higher in obese than nonobese patients for systolic BP (P <.01) and diastolic BP (P <.05).

CONCLUSIONS

The findings of increased heart rate and BP variability in obese children with isolated systolic hypertension suggest that sympathetic nervous system hyperactivity may contribute to its pathogenesis.