A revised classification table for pediatric hypertension has increased the estimated prevalence of elevated blood pressure (BP) in children and adolescents by 20%, new data show.
Further analysis indicate there is a clustering of other risk factors, such as obesity and dyslipidemia, among the youth whose risk is upgraded under the new guidelines, which one expert says is “somewhat reassuring.”
In 2017, the American Academy of Pediatrics published new clinical practice guidelines for pediatric hypertension. The revised guidelines, which replaced those developed in 2004 by the National Institute of Health’s National Heart, Lung, and Blood Institute, include new normative BP tables that lower abnormal BP cutoffs for most age groups by several mm Hg.
The change effectively reclassifies a percentage of BPs that had been deemed normal as abnormal, Atul K. Sharma, MD, FRCPC, from the Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, Manitoba, Canada, and colleagues report in an article published online April 23 in JAMA Pediatrics.
To determine the degree to which the reclassification would influence the prevalence of children and adolescents with elevated BP and hypertension, the investigators applied the previous and new classifications to the same data drawn from the National Health and Nutrition Examination Surveys (from January 1, 1999, to December 31, 2014).
According to the 2004 guidelines, the estimated weighted population prevalence of elevated BP among 15,647 generally healthy, low-risk children aged 5 to 18 years in the study population was 11.8% (95% confidence interval, 11.1%-13.0%). With the 2017 reclassification, 14.2% (95% confidence interval, 13.4%-15.0%) of this population had BPs considered to be abnormal, the authors write.
Moreover, nearly 6% of children in the study (905 of 15,584) were reclassified upward under the revised guidelines, including 381 who had been considered normotensive by National Heart, Lung, and Blood Institute standards but are now considered to have elevated BP (368 children) or stage 1 levels (13 children) by American Academy of Pediatrics criteria. Further, 470 children previously classified as prehypertensive were reclassified as having stage 1 hypertension, and 54 who had been deemed stage 1 hypertensive were reclassified as stage 2, the authors report.
Of the full cohort, 13,207 children (84.8%) had BPs in the normal range based on both classification systems. When the research compared this group with those who were reclassified under the new system in an sex-, age-, and height-matched analysis, they found that those in the reclassified group were significantly more likely to be overweight or obese based on a body mass index z score higher than 1 (55.9% vs 35.0%), and obese based on a body mass index z score higher than 2 (23.5% vs 11.6%).
Differences in lipid profiles were also observed. According to established clinical cutpoints, the children and adolescents who were reclassified upward were more likely to have elevated concentrations of total cholesterol (12.4% vs 9.3%; P = .06), low-density lipoprotein cholesterol (12.2% vs 3.9%; P = .002), triglycerides (22.6% vs 10.7%; P < .001), and hemoglobin A1c (3.4% vs 0.6%; P = .02).
To determine the prevalence of concurrent cardiac risk factors, the researchers conducted a comparative analysis of patients for whom complete data on all of these measures was available (126 in the case group and 140 in the control group) and determined that 67.5% of cases with complete data had risk factors above and beyond elevated BP and 19.0% had more than 2 additional risk factors, compared with 35% and 3.6%, respectively, among the control group.
“Based on recommendations from the 2017 [American Academy of Pediatrics] subcommittee report, the mean of multiple ausculatory BP readings at a single visit is used to formulate follow-up instructions; for these children, reclassification has consequences,” the authors write.
The additional disease burden associated with the upward classification is not trivial, they emphasize. “For those with elevated BP, lifestyle modifications are recommended (healthy diet, sleep, and physical activity), and the BP is to be reassessed after 6 months instead of 1 year as in children with normal BP. Similarly, asymptomatic children with stage 1 levels should be reassessed in 1 to 2 weeks, and those with stage 2 levels require more urgent evaluation or referral to a subspecialist within the week.”
The increased likelihood of upward classification among children who were overweight or obese, and the increased prevalence of additional cardiac risk factors in otherwise healthy children and adolescents, suggests that cardiovascular risk has been underestimated in the pediatric population, the authors write: “Clustering of risk factors suggests that reclassified children represent a high-risk population, which serves to validate the new, more stringent 2017 guidelines.”
The study has certain limitations that prevent a truly accurate estimation of the prevalence of hypertension in children, cautions Stephen R. Daniels, MD, PhD, from the Department of Pediatrics, University of Colorado School of Medicine, Aurora, in an accompanying editorial.
The use of National Health and Nutrition Examination Surveys data, in particular, is a “major disadvantage” because it is a single cross-sectional set of measures, he writes. “This is problematic for the evaluation of hypertension, as diagnosis of hypertension in pediatric patients requires blood pressure to be persistently elevated across multiple occasions.”
The sample size also limits the usefulness of the findings because it “does not permit meaningful assessment of age-, race-, and sex-specific differences, which may be important in comparing the previous approach with the new one,” Daniels continues.
The question that needs an answer, according to Daniels, is how to identify children and adolescents who have a high lifetime risk of developing cardiovascular disease. “Unfortunately, at present, we are left with using the best evidence available, which does not allow clear identification of lifetime risk of [cardiovascular disease],” he states, stressing that more research is warranted.
That said, the clustering of risk factors is “somewhat reassuring,” he writes. “We know from the Bogalusa Heart Study that clustering of [cardiovascular disease] risk factors in childhood is associated with greater development of atherosclerotic lesions in adolescence and young adulthood.”
“While we wait for additional studies, clinicians should use the new American Academy of Pediatrics Clinical Practice Guidelines in their practice,” Daniels states. “There are many elements that make the new guidelines easier to use than the old ones. In addition, use in practice will provide important clinical data that can ultimately contribute to improvements in our clinical approach to pediatric hypertension.”
The authors of the study and accompanying editorial have disclosed no relevant financial relationships.
JAMA Pediatr. Published online April 23, 2018. Article full text, Editorial extract
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