Routine measurement of blood pressure in schoolchildren

Prevalence of hypertension among high school students in a middle Anatolian province of Turkey

Hypertension may lead to irreversible damages in vital organs, such as heart, brain, and kidney, and may cause death in children if treatments are not given despite early diagnosis. This cross-sectional epidemiological study was conducted during 1 January-31 March 2004 to investigate the prevalence of hypertension among high school students. The study cohort included 1,041 students of six high schools, who were selected from among 14,789 students of 26 high schools in Sivas province of Turkey, using the cluster-sampling method. A questionnaire was used for collecting information from students on age, gender, smoking, and whether they or their families have any diseases. Blood pressure, height, and weight of the participitants were determined by the research group. Students whose repeated systolic or diastolic blood pressures were higher than the 95th percentile were considered to be hypertensive patients. Hypertension was prevalent among 4.4% (n=45) of the students. There was a significant correlation between prevalence of hypertension and body mass index. No significant correlation was found between prevalence of hypertension and other variables, such as smoking, age, gender, and family history of diabetes. The results suggest that hypertension is an important public-health problem among high school students. The results also showed that the body mass index was an important parameter in hypertension in such a study group. Researchers should consider overweight a causative risk factor for development of hypertension in early-onset groups.

Identifying children at high risk for the development of essential hypertension

BACKGROUND AND OBJECTIVES

Because blood pressure (BP) tracks from childhood to adulthood, some have recommended screening to identify children at high risk for the development of essential hypertension as adults. Others, however, have argued against this strategy because they believe that correlations between childhood and adulthood BP levels are too low. To address these issues, we considered prediction of adult BP from childhood levels.

DESIGN

Cohort study with follow-up of participants from childhood to early adulthood.

SETTING AND PARTICIPANTS

We ascertained BP in 337 schoolchildren from East Boston, Mass., and reexamined 317 (94%) of them 8 to 12 years later, at ages 18 to 26 years. MEASUREMENTS AND DATA ANALYSIS: On each of several visits, 1 week apart (four for children, three for adults), we obtained three BP readings with a random-zero sphygmomanometer. To calculate correlation coefficients (tracking correlations) between childhood and adult BP, we assumed a multivariate normal distribution and used an iterative maximal likelihood approach in a longitudinal model. We then used these correlations in expressions for sensitivity and specificity of childhood BP as a screening test and for positive predictive value for adult BP above specified cutoff points.

RESULTS

During the 8- to 12-year interval, tracking correlations, corrected for within-person variability and adjusted for age, sex, smoking, and medication and alcohol use, were 0.55 for systolic BP and 0.44 for diastolic BP. The corresponding positive predictive values indicated that, for example, the probability that a 20-year-old man's true systolic BP will be > 139 mm Hg (> 90th percentile) was 0.44, given that his observed average systolic BP at age 10 years was > 95th percentile (> 117 mm Hg). The sensitivity of a 10-year old boy's systolic BP > 95th percentile to detect systolic BP > 139 mm Hg 10 years later was 0.17. The specificity of his BP < 95th percentile at age 10 years to detect systolic BP < 139 mm Hg at age 20 years was 0.97. For diastolic BP, predictive values and sensitivities were somewhat lower.

CONCLUSIONS

After correction for within-person variability, tracking correlations from childhood to early adulthood are higher than previously reported. However, the resulting sensitivities and predictive values for childhood BP as a screening test for adult BP are of only modest magnitude. These data call into question the usefulness of routine BP measurement to identify children at high risk for the development of essential hypertension.

Childhood prevention of essential hypertension

Childhood prevention of essential hypertension requires knowledge of alterable determinants of blood pressure in children; these include obesity and sodium intake and perhaps physical activity and intake of potassium and calcium. Altering these determinants may involve two general preventive strategies. The first is a population strategy, which attempts to lower blood pressure (or keep it from rising) among all children. Population strategies may require educating children to active participants in changing their behaviors (active approach) or may merely change their environment (passive approach). The second general strategy aims to focus on children at high risk of developing hypertension as adults. To determine the usefulness of this high-risk strategy, more information is needed about prediction of adult blood pressure from childhood values and about the efficacy of interventions to control blood pressure levels in high-risk children.