The prevalence of hypertension in children ranges from 2% to 5%; however, children frequently go undiagnosed.
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This is largely due to omission of blood pressure (BP) measurement or, when BP is measured, the failure to correctly recognise hypertensive values. Up to 70% of pediatric physicians measure BP only when risk factors for hypertension are present.5
In addition, when BP is measured and meets hypertensive criteria, up to 74% of patients are not diagnosed with hypertension.3
This may be because pediatric physicians often do not compare measured BP with the diagnostic BP tables.5
These tables are cumbersome to use in clinical practice because they contain hundreds of values and also require that a child’s height is known. It has been suggested that the difficulty of using these tables contributes to the underdiagnosis of hypertension.3
Defining the Problem … Is a Problem
In recent decades, pediatric hypertension has been defined as a BP above the 95th percentile for age, sex, and height.
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Before 1996, BP norms were based only on age and sex, but it was noted that increasing height is associated with increasing BP in children, and as such height centile was added to the normative tables.8
Normative values were determined by examining the distribution of blood pressures among more than 60,000 children in the United States and have been updated over the years.National High Blood Pressure Education Program Working Group on Hypertension Control in Children and Adolescents. Update on the 1987 Task Force Report on High Blood Pressure in Children and Adolescents: a working group report from the National High Blood Pressure Education Program.
Pediatrics. 1996; 98: 649-658
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,National High Blood Pressure Education Program Working Group on Hypertension Control in Children and Adolescents. Update on the 1987 Task Force Report on High Blood Pressure in Children and Adolescents: a working group report from the National High Blood Pressure Education Program.
Pediatrics. 1996; 98: 649-658
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The 2017 Clinical Practice Guideline published by the American Academy of Pediatrics (AAP) updated the 4th Report normative values based on data obtained from only normal-weight children.9
This was done because it is recognised that overweight and obese children often have higher BP than their normal-weight counterparts. The AAP guideline also recommends using threshold cutoffs of ≥ 120 systolic but < 80 diastolic to define elevated BP, and ≥ 130/80 to define hypertension in children 13 years of age and older to be consistent with the adult American Heart Association/American College of Cardiology BP recommendations.9
Unfortunately, the childhood classifications are based on population norms and not on hypertensive target organ damage or trial outcome measures, which are needed to better refine the pediatric BP definitions.Evaluating Static Blood Pressure Cutoffs
There is limited research examining whether use of static BP cutoffs link to cardiovascular outcomes in children. Static BP cutoffs are threshold values to define hypertension, used across multiple age groups, and not dependent on height. In this issue of the Canadian Journal of Cardiology, Yang et al. report on the ability of static BP cutoffs to determine elevated carotid intima-media thickness (cIMT) in an international pediatric cohort.
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They compared the performance of these static cutoffs to the 95th percentile cutoffs outlined in the AAP 2017 Clinical Practice Guideline. For children aged 6-12 years, they used a BP of ≥ 110/70 mm Hg to define elevated blood pressure and BP ≥ 120/80 mm Hg to define hypertension. For adolescents aged 13 years or above, BP ≥ 120/< 80 mm Hg defined elevated BP and ≥ 130/80mm Hg was classified as hypertension.This was an international cross-sectional study including 4280 children aged 6-17 years.
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The cohort included children from 6 countries—Brazil, China, Greece, Italy, Spain, and the United Kingdom. BP, cIMT, demographic data, and other cardiometabolic risk factors were recorded during 1 study visit, and there was no long-term follow-up. Yang et al. demonstrate that pediatric hypertension is associated with elevated cIMT. With the use of static cutoffs, hypertension was associated with elevated cIMT with an odds ratio of 1.65 (confidence interval [CI] 1.25-2.17) after adjusting for potential confounding factors. The AAP guidelines’ 95th percentile tables had a slightly lower odds ratio of 1.46 (CI 1.15-1.86) for risk of elevated cIMT. This study provides evidence that static threshold values have a correlation similar to complex BP tables for childhood hypertensive target organ damage, with the implication that the easier-to-use cutoff BP values may be equally useful clinically.Despite the study’s robustness, it has a few limitations. First, although multiple BP measurements were taken, they were all from a single clinic visit instead of the multiple occasions that are required to demonstrate persistence of elevated BP readings in children. cIMT was measured and recorded slightly differently at some of the study sites, and different devices were used for BP and cIMT across study sites. The multisite and international nature of their study makes the results of the paper more applicable to a wide pediatric population, yet the individual cohorts differed in their rates of hypertension and obesity. One must also keep in mind, as with all cross-sectional studies, that association does not prove causality. Yet it is rare in pediatric studies to be able to analyse data from such large cohorts. Another unique feature of this paper is that they used a static BP cutoff for younger children, whereas much of the previous literature has used static cutoffs only for adolescents. Having static cutoffs for younger children in addition to adolescents has the potential to increase the early recognition of BP abnormalities in children and has been included in Hypertension Canada’s 2020 guideline recommendations.
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There has been increasing literature to suggest that using static cutoffs to diagnose pediatric hypertension may be appropriate. In addition to the contribution by Yang et al., a couple of studies have examined how static BP cutoffs correlate with short-term end-organ damage in childhood.
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The International Childhood Vascular Function Evaluation Consortium examined the ability of static BP cutoffs to identify elevated pulse-wave velocity compared with the 2017 AAP guideline.12
The consortium used the same BP cutoffs as Yang et al. and found that hypertension was associated with increased arterial stiffness and that static BP cutoffs performed equally well to identify elevated pulse-wave velocity.12
In addition, Khoury et al. reported a comparison of the 4th Report percentile BP tables with the AAP BP classification to detect cardiovascular end-organ damage in adolescent overweight and diabetic patients.13
They found that the AAP threshold BP definition had improved sensitivity to detect target-organ damage, including increased left ventricular mass, pulse-wave velocity, and cIMT.13
There have also been a few studies examining the ability of childhood BP thresholds to predict adulthood cardiovascular outcomes. Xi et al. examined the ability of static BP cutoffs to predict adulthood increased cIMT, pulse-wave velocity, and left ventricular hypertrophy in the Bogalusa Heart Study cohort.
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In that cohort of 1225 children and adolescents with 27-year follow-up data, threshold BP cutoffs were able to predict composite adverse adult cardiovascular outcomes equally as well as the 4th Report percentile tables.14
Also analysing the Bogalusa Heart Study participants from childhood to adulthood, Du et al. reported on the risk of developing adulthood hypertension, left ventricular hypertrophy, or metabolic syndrome using the 4th Report compared with the AAP guidelines, including adolescent thresholds, to define pediatric hypertension.15
Of the 3940 study participants, 325 were reclassified to a higher BP category with the use of the AAP classification, and those patients were at higher risk of adverse adult cardiovascular outcomes than their normotensive counterparts.15
Using data from the Cardiovascular Risk in Young Finns Study, Aatola et al. examined the association of childhood BP by simplified cutoff thresholds and complex percentiles with the development of adulthood elevated pulse-wave velocity. They found that age-specific cutoffs were able to predict adult elevated pulse-wave velocity with accuracy similar to the percentile tables.16
So, Do Cutoffs Make the Cut?
Yang et al. have made a substantial contribution to the evidence that supports using static cutoffs for defining pediatric hypertension. We now have evidence that during childhood, threshold BP values are as associated with cardiovascular target-organ damage, including increased cIMT and pulse-wave velocity, as the complex BP tables.
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There is also evidence that threshold BP values in childhood are equally predictive of adulthood cardiovascular disease, including hypertension, metabolic syndrome, left ventricular hypertrophy, increased cIMT, and arterial stiffness.14
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The strength of the evidence in the studies is likely the best we can expect because we are unlikely to ever have a study of long enough duration to link childhood BP values to adulthood cardiovascular mortality while controlling for all confounding factors over a lifetime.In fact, the most recent pediatric guidelines from the AAP, European Society of Hypertension, and Hypertension Canada all recommend using threshold BP values to define hypertension during childhood or adolescence.
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The trouble is that each guideline recommends slightly different BP cutoffs because the evidence to support the thresholds is new and evolving. Yet given the high rates of underdiagnosis of hypertension in children, it is time to start using threshold BP cutoffs in pediatrics. And while we use the cutoffs, we need to continue to evaluate the utility of the thresholds to identify hypertension, to predict target-organ damage, and to better determine the most accurate static values to use.Funding Sources
The authors have no funding sources to declare.
Disclosures
The authors have no conflicts of interest to disclose.
References
- Overweight, ethnicity, and the prevalence of hypertension in school-aged children.Pediatrics. 2004; 113: 475-482
- Body mass index and blood pressure screening in a rural public school system: the Healthy Kids Project.Prev Chronic Dis. 2006; 3: A114
- Underdiagnosis of hypertension in children and adolescents.JAMA. 2007; 298: 874-879
- Patient-, provider-, and clinic-level predictors of unrecognized elevated blood pressure in children.Pediatrics. 2010; 125: e1286-e1293
- Why pediatricians fail to diagnose hypertension: a multicenter survey.J Pediatr. 2014; 164: 173-177.e7
- National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents.Pediatrics. 2004; 114: 555-576
- Hypertension Canada’s 2018 guidelines for diagnosis, risk assessment, prevention and treatment of hypertension in adults and children.Can J Cardiol. 2018; 34: 506-535
- National High Blood Pressure Education Program Working Group on Hypertension Control in Children and Adolescents. Update on the 1987 Task Force Report on High Blood Pressure in Children and Adolescents: a working group report from the National High Blood Pressure Education Program.Pediatrics. 1996; 98: 649-658
- Clinical practice guideline for screening and management of high blood pressure in children and adolescents.Pediatrics. 2017; 140e20171904
- Use of static cutoffs of hypertension to determine high cIMT in children and adolescents: An international collaboration study.Can J Cardiol. 2020; 36: 1467-1473
- Hypertension Canada’s 2020 comprehensive guidelines for the prevention, diagnosis, risk assessment, and treatment of hypertension in adults and children.Can J Cardiol. 2020; 36: 596-624
- Static cut-points of hypertension and increased arterial stiffness in children and adolescents: the International Childhood Vascular Function Evaluation Consortium.J Clin Hypertens. 2019; 21: 1335-1342
- Clinical implications of the revised AAP pediatric hypertension guidelines.Pediatrics. 2018; 142e20180245
- Can pediatric hypertension criteria be simplified? A prediction analysis of subclinical cardiovascular outcomes from the Bogalusa Heart Study.Hypertension. 2017; 69: 691-696
- 2017 pediatric hypertension guidelines improve prediction of adult cardiovascular outcomes.Hypertension. 2019; 73: 1217-1223
- Simplified definitions of elevated pediatric blood pressure and high adult arterial stiffness.Pediatrics. 2013; 132: e70-e76
- Evidence gaps in the identification and treatment of hypertension in children.Can J Cardiol. 2020; 36: 1384-1393
Article info
Publication history
Published online: May 24, 2020
Accepted:
May 20,
2020
Received:
May 1,
2020
Footnotes
See article by Yang et al., pages 1467–1473 of this issue.
See page 1334 for disclosure information.
Identification
Copyright
© 2020 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.
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- Use of Static Cutoffs of Hypertension to Determine High cIMT in Children and Adolescents: An International Collaboration StudyCanadian Journal of CardiologyVol. 36Issue 9
- PreviewPediatric hypertension is typically defined as blood pressure ≥ sex-, age-, and height-specific 95th percentile (high) cutoffs. Given the number of strata, there are hundreds of cutoffs for defining elevated and high blood pressure that make it cumbersome to use in clinical practice. This study aimed to evaluate the utility of the static cutoffs for pediatric hypertension (120/80 mm Hg for children and 130/80 mm Hg for adolescents) in determining high carotid intimamedia thickness (cIMT) in children and adolescents.
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