Elevated BP on the Rise in US Children Aged 8 to 17 Years

Laurie Barclay, MD

July 17, 2013

The risk for elevated blood pressure (BP) among children and adolescents rose 27% during a 13-year period, according to a population-based study published online July 15 in Hypertension. Obesity and excess salt intake were associated with elevated BP.

"High [BP] is dangerous in part because many people don't know they have it," lead author Bernard Rosner, PhD, professor of medicine at Harvard Medical School in Boston, Massachusetts, said in a news release. "It's a very sneaky thing. Blood pressure has to be measured regularly to keep on top of it."

To examine the rates of elevated BP, Dr. Rosner and colleagues analyzed a sample of 3248 children aged 8 to 17 years who were enrolled in the National Health and Nutrition Examination Survey (NHANES) III from 1988 to 1994, and 8388 similarly aged children enrolled in continuous NHANES from 1999 to 2008.

"The obesity epidemic in children makes it plausible that prevalence rates of elevated [BP] are increasing over time...[but] it is unclear whether adjusting for risk factors can explain longitudinal trends in prevalence of elevated BP," the study authors write.

Between NHANES III and NHANES 1999-2008, the prevalence of elevated BP, defined as systolic or diastolic BP in the 90th percentile or higher or systolic BP/diastolic BP at 120/80 mm Hg or higher, increased. For boys, the prevalence of elevated BP rose from 15.8% to 19.2% (P = .057), and for girls, it rose from 8.2% to 12.6% (P = .007). However, the researchers could not determine the prevalence of hypertension, as the diagnosis requires 3 consecutive elevated BP readings.

They also found that from NHANES III to NHANES 1999-2008, the proportion of children with a body mass index (BMI) in the 85th percentile or higher increased, as did the proportion of children with larger waist circumference, especially in girls.

Factors independently associated with prevalence of elevated BP were BMI (fourth vs first quartile odds ratio [OR], 2.00; P < .001), waist circumference (fourth vs first quartile OR, 2.14; P < .001), and sodium intake (≥3450 vs <2300 mg/2000 calories OR, 1.36; P = .024).

Compared with non-Hispanic white children, black children had a 28% higher risk for elevated BP.

Mean systolic, but not diastolic, BP was associated with increased sodium intake (fifth vs first quintile of sodium intake; β = 1.25 ± 0.58; P = .034).

After adjustment for age, sex, race/ethnicity, BMI, waist circumference, and sodium intake, OR for elevated BP in NHANES 1999-2008 vs NHANES III was 1.27 (P = .069).

The authors note several study limitations, including a single dietary intake assessment using a 24-hour recall, insufficient power to assess lower levels of sodium intake, and a lack of data regarding physical activity.

Clinical Implications

It is important to prevent and control elevated BP, which is a risk factor for stroke, heart disease, and kidney failure and contributes to approximately 350,000 preventable deaths annually in the United States.

Findings of this study suggest that reducing BMI, abdominal obesity, and sodium intake may help prevent elevated BP. In children and adolescents, reducing sodium intake may reduce average systolic BP by 1.2 mm Hg and average diastolic BP by 1.3 mm Hg.

In the United States, average daily sodium intake is 3400 mg, whereas the American Heart Association recommends that it not exceed 1500 mg. Store-bought foods typically account for two thirds of sodium intake, and restaurant foods for one quarter.

In NHANES III and NHANES 1999-2008, more than 80% of children had daily sodium intake exceeding 2300 mg. However, fewer children in NHANES 1999-2008 than in NHANES III had daily sodium intake exceeding 3450 mg. Children with the highest sodium intake were 36% more likely than those with the lowest intake to have elevated BP.

"Everyone expects sodium intake will continue to go up," Dr. Rosner said in the news release. "It seems there's been a little bit of listening to dietary recommendations, but not a lot."

The National Institutes of Health supported this study. The study authors have disclosed no relevant financial relationships.

Hypertension. Published online July 15 2013. Abstract

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