A demographic approach to assess elevated blood pressure and obesity in prepubescent children: the ExAMIN Youth South Africa study

Validation of a short food group questionnaire to determine intakes from healthy and unhealthy food groups in 5-9-year-old South African children

BACKGROUND

Reliable dietary data for children are necessary to investigate associations with health outcomes. The present study aimed to develop and validate a questionnaire to determine the frequency of intakes of specific healthy and unhealthy food groups in young children.

METHODS

Participants were 5-9-year-old South African children (n = 920) from 10 urban schools. Their parents completed a demographic questionnaire and the food intake questionnaire with food pictures. Based on the literature, four healthy food groups (fruits, vegetables, milk, meat/fish/poultry/eggs) and six unhealthy food groups (hot and cold sugar-sweetened beverages, candy, salty snacks, cakes and fast foods) were included, with five different frequency responses. Six experienced nutritionists assessed the face validity and content validity. After pilot testing, construct validity and homogeneity were determined in the participants. Convergent validity was determined using urinary sodium and potassium concentrations as biological intake markers.

RESULTS

Nutritionists confirmed face and content validity. Caregivers confirmed understanding of the questionnaire. Three factors explained 50.2% of the variance, with most unhealthy food groups as factor 1, fruits and vegetables as factor 2, and animal source protein and milk groups clustered with sugar-sweetened beverages as factor 3. The frequency of milk group, fruits and vegetables intake correlated negatively, whereas the frequency of salty snacks and fast foods intakes correlated positively with the urinary sodium:potassium ratio.

CONCLUSIONS

The healthy and unhealthy food group questionnaire has advantages of low respondent burden, as well as acceptable content and convergent validity in South African children. The questionnaire may be used to investigate associations between food intakes and health outcomes.

Food intake in South African children and retinal microvascular health: The ExAMIN Youth SA study

BACKGROUND AND AIMS

Retinal arteriolar narrowing and venular widening are associated with increased cardiovascular risk, even at young ages. Whether diet contributes to early microvascular changes in children is not widely explored. We explored the associations of frequency of healthy and unhealthy food group intake with retinal vessel calibers in black and white children.

METHODS AND RESULTS

This study included school-aged (5-9 years) black (N = 433, 7.46 ± 0.98 years), and white (N = 403, 7.43 ± 0.82 years) children. Anthropometric and blood pressure measurements were taken, along with retinal vessel calibers (central retinal arteriolar (CRAE) and venular (CRVE) equivalents). Frequencies of food group intake were assessed using a food-frequency questionnaire. A factor analysis was performed to describe food group patters. Independent associations between retinal vessel calibers and frequencies of food group intake and food group patters were explored. In black children, cookies, cakes, and biscuits were associated with narrower arterioles (p < 0.05). In white children, cold sweetened beverages were associated with narrower arterioles (p = 0.02), whereas salty snacks were associated with narrower arterioles (p = 0.01) and wider venules (p < 0.05). Fruits were positively associated with CRAE (p = 0.03) in white children only.

CONCLUSION

A higher frequency of unhealthy food group consumption was associated with retinal arteriolar narrowing and venular widening in both black and white children. However, fruit intake was shown beneficial for retinal microvascular health in white children only. Our findings may highlight the importance of promoting healthy eating patterns from early childhood which may reduce the risk of premature cardiovascular disease development.

Detecting and Managing Childhood Onset Hypertension in Africa: A Call to Action

PURPOSE OF REVIEW

To review recent evidence on childhood hypertension across Africa, identifying knowledge gaps, challenges and priorities, and highlight clinical perspectives in managing primary hypertension.

RECENT FINDINGS

Only 15 of the 54 African countries reported on absolute blood pressure (BP) measures, elevated BP, pre- and/or hypertension. The reported hypertension prevalence ranged between 0.0 and 38.9%, while elevated BP and/or pre-hypertnesion ranged from 2.7 to 50.5%. Childhood BP nomograms are lacking across Africa and the rates of hypertension were based on guidelines developed in countries with the lowest to no number of children from African ancestry. The recent studies across Africa also showed little to no detail when reporting BP specific methodology. No recent data informing the use or effectiveness of antihypertensive agents in children and adolesents are available. Childhood hypertension is on the rise, while data from Africa remains vastly under-represented. Collaborative research, resources, and policies need to be strengthened in addressing the growing public health concern of childhood onset hypertension on this continent.

Temporal Associations between Tri-Ponderal Mass Index and Blood Pressure in Chinese Children: A Cross-Lag Analysis

Background: No longitudinal studies have explored the relationship between tri-ponderal mass index (TMI) and blood pressure (BP) in children. This study is aimed to investigate the temporal associations between TMI and BP among children in China. Methods: A longitudinal study was carried out with Chinese children from 2014 to 2019. Data of the anthropometric examination and blood pressure were collected annually. TMI was calculated by dividing weight by the cube of height. BP was measured using a standard mercury sphygmomanometer. We investigated temporal associations between TMI and BP with a cross-lagged panel model using repeated measure data from 2014 (Wave 1), 2016 (Wave 2), and 2018 (Wave 3). Results: Results of the cross-lagged panel model showed that TMI was associated with subsequent BP. Participants with higher levels of TMI presented higher levels of BP (Wave 1: β = 0.737 for systolic blood pressure (SBP) and β = 0.308 for diastolic blood pressure (DBP), Wave 2: β = 0.422 for SBP and β = 0.165 for DBP, p < 0.01). In addition, children with higher BP could also present higher TMI (Wave 1: β = 0.004 for SBP and β = 0.006 for DBP, Wave 2: β = 0.003 for SBP and β = 0.005 for DBP, p < 0.01), but the cross-lag path coefficient indicated that the influence of TMI on BP was stronger than the influence of BP on TMI. Conclusions: There was a temporal association between TMI and BP in Chinese children. Higher TMI predicted higher subsequent BP rather than the reverse relationship.

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.