High Blood Pressure in School Children: Prevalence and Risk Factors

Ximena Urrutia-Rojas; Christie U. Egbuchunam; Sejong Bae; John Menchaca; Manuel Bayona; Patrick A. Rivers; Karan P. Singh

Disclosures

BMC Pediatr 

In This Article

Discussion

In this study, SBP > 95th percentile accounted for nearly all of the cases of BP > 95th percentile. The prevalence of BP > 95th percentile among children reported in earlier studies ranged from 1.2 % to 13 %.[7,8,9] However, in a more recent study that included mostly minority school children, the prevalence of BP > 95th percentile was 17 % at the first screening.[11] Similarly, in our study, 16 % of children had SBP > 95th percentile, (with or without DBP > 95th percentile), and 2 % had DBP > 95th percentile (with or without SBP > 95th percentile) at the first screening. The results of these studies suggest that BP > 95th percentile is not rare in children. Females showed a slightly higher risk of BP > 95th percentile than males (Adjusted OR = 1.30; CI: 0.93, 1.81).

In contrast to previous studies reporting higher BP levels in African American children when compared to their Caucasian counterparts,[19,20,21,22,23] results of this study show that Hispanic children were more likely to have HBP than African American or Caucasian children. Previous studies have either compared Hispanics versus Caucasians, or African Americans versus Caucasians. In this study, however, these three groups were compared simultaneously. African American children showed slightly higher odds ratios when compared to Caucasian children. The crude analysis showed an increased likelihood for Hispanic (71%) children to have a BP ≥ 95th percentile. Sorof et.al[11] compared these three ethnic groups simultaneously and reported a higher prevalence of BP ≥ 95th percentile among Hispanic children, at the first reading. Our findings may be influenced by the higher prevalence of obesity among the minority children in the sample.[45,46] However, the prevalence of obesity was slightly higher in African American than in Hispanic children (32.8 % and 31.9 %, respectively) in this sample.

Other hypertension studies that have evaluated socioeconomic status and stress in African American and Caucasian children, have found higher rates of HBP among African Americans.[47,48] These studies concluded that exposure to chronic environmental stress and low socioeconomic status contributes to hypertension among African American youth. Although our study did not evaluate socioeconomic status or stress, our study population was from the Fort Worth Independent School District, a school district with a large minority student population. Thus, it may be more homogenous in comparison to school districts in larger cities.

In this study, obesity was the most important identified factor affecting the BP distribution in this sample of children. This finding was consistent with other studies that evaluated BP in children.[14,15,25,30,31,32,33,45] Among all children in this study, being overweight increased the likelihood of hypertension over three times, after adjusting for age, gender and ethnicity.

Several factors may have influenced the prevalence of HBP, as well as the strength of the associations found in this study: 1) the high prevalence of obesity in this population; 2) use of the automated oscillometric instead of the auscultatory method[49] to measure BP; 3) family history of hypertension and socioeconomic status, were not available in this study; 4) the lower likelihood of HBP in African American children compared to white may be due to the smaller sample size of African American (n = 250) and Caucasian (n = 170) children as compared to Hispanic children (n = 598); and 5) because of the local nature of the study and the non-random sample, these findings cannot be generalized to the rest of the population; 6) since this was a cross-sectional study, exposures, disease, and/or outcome were assessed at a single point in time, therefore it is not possible to elucidate whether exposures preceded or resulted from the outcome variable.[55,56]

There is controversy regarding the discrepancies between the oscillometric and auscultatory methods of BP measurements.[50,51,52,53,54] Weaver et al. showed that auscultatory SBP levels were 6.4 mm Hg lower, and DBP levels were 8.7 mm Hg higher than their oscillometric measurements.[51] Park et al. reported that both SBP and DBP levels were higher with the oscillometric method.[51,53] Conversely, O'Brien reported lower SBP and DBP levels with the automated monitor Dinamap.[54] Still, these findings were challenged in other studies which compared the accuracy of Dinamap monitors with BP measurements using invasive methods in adult, pediatric, and neonatal patients.[40,50] The Dinamap appears to be an accurate and reliable technique for non-invasive measurement of BP. It is simple to use, shows consistency over time, is more acceptable to children, and can be appropriate for BP screening.[41] In spite of these methodological issues, the findings of this study are consistent with recent studies that show HBP in children is increasing rapidly, especially among minority children. Sorof et. al.,[11] using an automated oscillometric monitor, did show a prevalence of HBP ≥ 95th percentile) at 19% in school children at the first screening.

Results of this study show that factors associated with HBP (e.g., obesity and ethnicity), may play a role in the development of hypertension at an early age, and can be used as an independent marker for increased likelihood of HBP in children. Studies show that weight and height in pre-adolescents and adolescents is consistently highly associated with BP and thereby, predicts hypertension in adult life.[2,14,15,25,30,31,32,33,57,58] Obesity, which is associated with metabolic problems such as hyperinsulinemia, hyperlipidemia, diabetes and hypertension in young adults and children[59,60,61,62,63,64,65,66] was strongly associated with HBP in this study. The constellation of risk factors in this study, namely, obesity and BP > 95th percentile, should be interpreted as early indications of risk for chronic diseases such as type 2 diabetes and cardiovascular disease, diseases more commonly seen in adults. These findings show the need to encourage health care providers to screen children for HBP, or ideally, to include BP measurement in the child's routine physical exam, especially those who are overweight.[2] Furthermore, broader recommendations stem from our findings. A more aggressive approach toward promoting healthy lifestyle practices is a necessity if we are to prevent childhood obesity. Examples of healthy lifestyle practices include increased physical activity, restrictions on television watching or playing video games, and avoiding food with a high fat and simple sugar content. These lifestyle changes should be implemented in all children as early in life as possible.

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