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Hypertension Among Youths – United States, 2001-2016

Hypertension is an important modifiable risk factor for cardiovascular morbidity and mortality, and hypertension in adolescents and young adults is associated with long-term negative health effects (1,2).* In 2017, the American Academy of Pediatrics (AAP) released a new Clinical Practice Guideline (3), which updated 2004 pediatric hypertension guidance with new thresholds and percentile references calculated from a healthy-weight population. To examine trends in youth hypertension and the impact of the new guideline on classification of hypertension status, CDC analyzed data from 12,004 participants aged 12–19 years in the 2001–2016 National Health and Nutrition Examination Survey (NHANES). During this time, prevalence of hypertension declined, using both the new (from 7.7% to 4.2%, p<0.001) and former (from 3.2% to 1.5%, p<0.001) guidelines, and declines were observed across all weight status categories. However, because of the new percentile tables and lower threshold for hypertension (4), application of the new guideline compared with the former guideline resulted in a weighted net estimated increase of 795,000 U.S. youths being reclassified as having hypertension using 2013–2016 data. Youths who were older, male, and those with obesity accounted for a disproportionate share of persons reclassified as having hypertension. Clinicians and public health professionals might expect to see a higher prevalence of hypertension with application of the new guideline and can use these data to inform actions to address hypertension among youths. Strategies to improve cardiovascular health include adoption of healthy eating patterns and increased physical activity (3).

NHANES is a nationally representative survey of noninstitutionalized persons in the United States. The survey includes an in-person examination with up to three brachial systolic blood pressure (SBP) and diastolic blood pressure (DBP) readings taken by certified examiners. Mean SBP and DBP values were used.§ Among 13,523 participating youths during 2001–2016, those missing SBP or DBP (999), or body mass index (BMI [kg/m2]) (136) were excluded. In addition, youths classified as underweight (BMI-for-age <5th percentile; 384) were excluded because of insufficient sample size, leaving 12,004 persons aged 12–19 years in the analytic sample.

Elevated blood pressure (BP) and hypertension were defined according to age-specific thresholds established in both the former and new guidelines. To apply the former guideline, among those aged 12–17 years, elevated BP (formerly “prehypertension”) was defined as BP ≥90th to <95th percentile or ≥120/80 mmHg to <95th percentile; hypertension was defined as BP ≥95th percentile (using 2004 age, sex, and height-specific percentile tables) or reported antihypertensive medication use (only available for persons aged >15 years) (Supplementary Table 1, https://stacks.cdc.gov/view/cdc/56579). Among persons aged 18–19 years, elevated BP was defined as SBP ≥120 mmHg to <140 mmHg or DBP ≥80 mmHg to <90 mmHg; hypertension was defined as BP ≥140/90 mmHg or reported antihypertensive medication use.

The new guideline used new percentile tables (from a reference population excluding youths with overweight/obesity). To apply the new guideline, among adolescents aged 12–17 years, elevated BP was defined as BP ≥90th to <95th percentile or SBP ≥120 mmHg to <95th percentile; hypertension was defined as BP ≥95th percentile, BP ≥130/80 mmHg, or reported antihypertensive medication use. For persons aged 18–19 years, elevated BP was defined as SBP ≥120 mmHg to <130 mmHg and DBP <80 mmHg; hypertension was defined as BP ≥130/80 mmHg or antihypertensive medication use. The new guideline thresholds for persons aged 18–19 years align with recommendations in the 2017 Hypertension Clinical Practice Guideline for persons aged ≥18 years.**

Weight status was categorized using age- and sex-specific reference values from the 2000 CDC growth charts†† (healthy weight: BMI-for-age ≥5th to <85th percentiles; overweight: ≥85th to <95th; obesity: ≥95th). In addition, a subset of the group with obesity (severe obesity, defined as BMI-for-age ≥120% of the 95th percentile) was examined (5). Race/ethnicity was classified as non-Hispanic white, non-Hispanic black, Mexican American, and other.§§

Participant characteristics across survey years were compared using Satterthwaite chi-squared tests and t-tests. Estimated prevalence of elevated BP, hypertension, and the combination of these were calculated in 4-year increments (to assure sufficient sample size) from 2001 to 2016, and trends were assessed using survey logistic regression adjusted for age, sex, and race/ethnicity. Using prevalence estimates from 2013 to 2016, population-level estimates of the number of youths classified as having hypertension were calculated. Bootstrap methodology with 1,000 resamples was used to estimate 95% confidence intervals for the percentage of the population reclassified as having hypertension. All analyses used exam sample weights and statistical procedures for complex surveys, and all tests were two-sided.

Population characteristics were mostly consistent from 2001 to 2016, although the prevalence of obesity increased from 17.8% (2001–2004) to 21.8% (2013–2016) (p = 0.016), as did the prevalence of severe obesity (5.7% to 8.8%, p = 0.003) (Table 1). During 2001–2016, the prevalence of hypertension declined, according to both the new (from 7.7% to 4.2%, p<0.001) and former (from 3.2% to 1.5%, p<0.001) guidelines (Figure) (Supplementary Table 2, https://stacks.cdc.gov/view/cdc/56580). This decline occurred across all BMI categories, although the prevalence of hypertension was consistently highest among persons with obesity and severe obesity. During 2013–2016, using the new guideline, the prevalence of elevated BP was approximately 10%, and the prevalence of combined elevated BP or hypertension was nearly 15% (Figure).

Compared with the former guideline, the new guideline classified fewer youths with elevated BP and more youths as having hypertension (Figure). Using data from 2013 to 2016, an additional 2.6% of U.S. youths aged 12–19 years would be reclassified as having hypertension, which translates to a net increase of approximately 795,000 persons (Table 2). Youths aged 18–19 years would account for approximately half of the net increase, and males would account for over two thirds. Nearly half of the net increase in new diagnoses of hypertension among youths would be among those with obesity (Table 2), although less than one quarter of U.S. youths have obesity (Table 1).

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