Reliability of normative tables in assessing elevated blood pressure in children

Practice Change Needed for the Identification of Pediatric Hypertension in Marginalized Populations: An Example From South Africa

INTRODUCTION

Hypertension in children has increased globally over the past 20 years; yet, little is known about this issue among disadvantaged communities from low- and middle-income countries. Age-, sex-, and height-adjusted normative tables are the "gold" standard for the diagnosis and estimation of pediatric hypertension worldwide, but it is unclear whether the use of international standards is appropriate for all contexts. The purpose of this study was to evaluate and compare different international references to identify hypertension among South African school-aged children from disadvantaged communities.

METHODS

Blood pressure, weight, and height were measured in a cohort of 897 children aged 8-16 years from eight peri-urban schools in the Eastern Cape of South Africa. Cross-sectional prevalence of hypertension was calculated according to American, German, and global normative tables, as well as pseudo-normative data from the own study population. Isolated systolic hypertension and body mass index (BMI) were considered markers for cardiovascular disease. Multinomial logistic regression was used to compare the likelihood of blood pressure categorization with increasing BMI levels.

RESULTS

Hypertension prevalence ranged from 11.4% with the pseudo-normative study tables to 28.8% based on the German reference. Global guidelines showed the highest agreement both among international standards (92.5% with American guidelines) and with the study reference (72.5%). While the global and the American references presented higher systolic over diastolic hypertension rates (23.6 vs. 10.6% and 24.2 vs. 14.7%, respectively), the American guidelines predicted the highest increased risk for hypertension stage 2 [odds ratio, 1.72 (95% confidence interval: 1.43-2.07)] with raising levels of BMI.

CONCLUSION

Our results support the heterogeneity of blood pressure estimates found in the South African literature, and highlight the underrepresentation of African children in international guidelines. We call for caution in the use of international standards in different contexts and advocate for the development of normative tables that are representative of the South African pediatric population necessary to ensure an accurate identification of hypertension both from the clinical and epidemiological perspective.

The Relationship of Circulating Homocysteine with Fibrinogen, Blood Pressure, and Other Cardiovascular Measures in African Adolescents

OBJECTIVES

To evaluate the associations between homocysteine (Hcy) and cardiovascular health in South African adolescents.

STUDY DESIGN

Circulating Hcy concentrations of 172 South African adolescents (105 girls, ages 13 to <18 years) were measured. Anthropometric and cardiovascular factors were also included and cross-sectionally analyzed through general linear models.

RESULTS

Hcy correlated positively with body weight (P = .03; after adjusting for multiple testing, it was not regarded as significant) and muscle mass (P = .01), but negatively with fibrinogen concentrations (P = .001). Across Hcy tertiles, blood pressure produced approximating U-shaped curves, with differences between the middle and upper tertiles (all P < .02). Forty percent of the adolescents had elevated blood pressure, of whom 37% fell in the lowest and 38% in the highest Hcy tertiles. Hcy differed between the sexes (with boys having higher Hcy), but not between subgroups based on puberty, weight, stunting, smoking, or alcohol consumption.

CONCLUSIONS

Both high and low Hcy could be early contributing risk factors to cardiovascular health. The associations between Hcy and blood pressure suggest that dietary and lifestyle manipulation, to achieve the optimal range of Hcy, may be beneficial in preventing Hcy-related hypertension in adulthood. The inverse relationship between Hcy and fibrinogen remains to be clarified.