New American guidelines result in more children with hypertension
Prevalence and Severity of High Blood Pressure Among Children Based on the 2017 American Academy of Pediatrics GuidelinesSharma AK, Metzger DL, Rodd CJ. - JAMA Pediatr 2018; published online ahead of print
Introduction and methods
When blood pressure (BP) was redefined for adults, the proportion of US adults with elevated BP was increased from 32% to 46% [1,2]. New guidelines for the diagnosis and management of elevated BP in children were also published recently, in which the percentile values were recalculated after excluding individuals who are overweight or obese. As a result, the percentile values were lowered by about 2 or 3 mm Hg across the range of percentiles. For adolescents aged 13 years or older, what was previously called pre-hypertension is now called elevated BP, since the adult cut-points apply now for adolescents as well [3,4]. The net effect of changes in population percentiles and diagnostic cut-offs is not known.
In this analysis, the consequences of the new guidelines on the prevalence and severity of elevated BP was assessed in an unselected and generally healthy sample of 15,647 children aged 5-18 years from the 1999-2014 National Health and Nutrition Examination Surveys (NHANES) . Moreover, clinical and laboratory risk factors were evaluated for children whose BP level was reclassified upward. Auscultatory BP was measured in a single ambulatory sitting.
- The sample prevalence of high BP increased from 2006 of 15,647 children under the previous definition (12.8%; 95%CI: 12.3%-13.0%) to 2337 of 15,584 children with the new definition (15.0%; 95%CI: 14.4%-16.0%) (P <0.001).
- The estimated population prevalence increased from 11.8% (95%CI: 11.1%-13.0%) to 14.2% (95%CI: 13.4%-15.0%).
- Overall 5.8% of children were reclassified upward under the new guidelines compared with the 2004 guidelines, whereas 470 children with pre-hypertension were reclassified as stage 1 hypertension, and an additional 54 children with previously stage 1 hypertension were reclassified as stage 2 hypertension.
- 84.8% of children were normotensive by both criteria.
- Compared with the normotensive children, those reclassified upward were more likely to be male (62.7% vs 47.6%; P <0.001) and slightly taller (height z score: 0.44±0.95 vs 0.11±1.0; P<0.001).
- The mean age of those reclassified upward was 12.2±3.4 years vs 13.2±2.8 years for controls with normal BP (P<0.001).
- The proportion of children who were overweight or obese (BMI z score >1) was 55.9% among those reclassified upward vs. 35.0% among controls with normal BP (P<0.001), and the proportion who were obese (BMI z score >2) was 23.5% among those reclassified upward vs. 11.6% among controls (P<0.001).
- Compared to normotensive children, those whose BP was reclassified upward with the new guidelines had also higher total cholesterol levels (164.9±1.0 vs 159.9±1.0 mg/dL; P=0.001), and higher hemoglobin A1c levels (3.4±1.0% vs 0.6±0.4%; P=0.02).
Based on the new BP definitions for children, the estimated population prevalence increased from 11.8% to 14.2%. Children whose BP was reclassified upward were more likely to be male, taller, younger, overweight or obese, and have higher cholesterol and hemoglobin A1c levels. The authors conclude that the new guidelines allow for early CV prevention in more children at higher risk.
In his editorial article, Daniels  criticizes the use of the NHANES database for this study, because the diagnosis of hypertension in children requires a persistent elevation of BP, but multiple BP measurements are not available in NHANES. Therefore, he notes that the prevalence of hypertension in children will be lower than that calculated by Sharma et al. The author also notes that ‘These “new” cases of elevated blood pressure were more likely to be found among children who were overweight or obese and those with abnormal lipid profiles and increased hemoglobin A1c levels (prediabetes). So, how should we evaluate whether the new clinical practice guidelines provide the best estimate of the prevalence of elevated blood pressure or not?’, and he concludes: ‘However, to know how much lower this prevalence will be will require future studies with longitudinal measurements. While we wait for additional studies, clinicians should use the new American Academy of Pediatrics Clinical Practice Guidelines in their practice. 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.’