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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 3, May/June 2019
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AFRICA
<
0.001) association between over-fatness and hypertension, both
unadjusted (OR
=
3.11; 95% CI
=
2.17–4.46) and adjusted for age
and gender (OR
=
3.29; 95% CI
=
2.22–4.86).
Discussion
The aim of this cross-sectional study was to determine the
association of fat patterning with blood pressure in Polokwane’s
privately educated school children aged five to 15 years old.
There was a significant association between fat patterning
variables and blood pressure. In this study, skinfold thickness
in girls was significantly higher than in boys. This result is in
agreement with the results of other studies which found higher
mean values of skinfold thickness and sum of skinfolds in girls
than boys.
9-12
Skinfold thickness is a better predictor of body fatness during
adolescence compared to BMI.
13
Skinfold thickness, especially
subscapular skinfold, increases the risk of cardiovascular
disease at an early age.
14,15
Freedman
et al
.
16
reported that
higher subscapular skinfold thickness was associated with
higher low-density lipoprotein cholesterol, triacylglycerol and
insulin concentrations. These conditions lead to lifestyle-related
diseases, especially cardiovascular disease, which is the leading
cause of death globally.
17
The prevalence of hypertension and over-fatness was high
in girls and increased with age in this sample. These results
disagree with the findings of Skapino
et al
.,
17
who found a higher
prevalence of hypertension in boys than girls. Hypertension
is such a major health problem in the black community in
South Africa and it could be useful to predict hypertension in
childhood and adulthood. In a study of 5 000 children in India,
obesity was found to be a significant risk factor for hypertension
in a childhood population.
18
Additionally, obesity is known to be
one of the most important risk factors for hypertension.
19
The results found in our study are similar to the findings
of Freedman
et al
.
20
and Ramírez-Vélez
et al
.,
11
as they found
a high prevalence of hypertension, overweight and obesity in
school children. Compared to the results found in the Polokwane
rural population (Ellisras area), the Ellisras children had a low
prevalence of hypertension
5
and overweight.
21
Monyeki
et al.
5
indicated that results from rural South African children are
different from urban South African children and children from
Western countries. The results found in this study support the
statement from Monyeki
et al.
5
The present study found a positive association between fat
patterning ratios and blood pressure. The findings of this study
agree with those of Monyeki
et al
.,
22
who found a significant
positive association of the variables BMI, S/ST and SS/SSTB
ratios, and the sum of the skinfolds with blood pressure. Gupta
et al
.
23
indicated that low socio-economic status favours higher
blood pressure in childhood and adulthood. However nutritional
factors are the largest environmental factors believed to cause
hypertension, which has been studied extensively. There is a need
to ethnically test a good intervention to diminish the prevalence of
hypertension among these populations, in order to minimise the
resultant high rates of cardiovascular morbidity and mortality.
24
A limitation of this study is that we did not include the socio-
economic level of the participants’ families, therefore we cannot
state whether children with a high prevalence of over-fatness and
hypertension were from a high- or middle-income population.
This study also did not include nutritional status and the physical
activities of the participants, so we do not know what foods
contributed to the incidence of hypertension and obesity, or
whether physical inactivity may have been the cause. Further
investigation is necessary, including nutritional status, physical
activity and socio-economic level of these Polokwane children.
Conclusion
Obesity and borderline hypertension were found in a significant
proportion of the sample of black school children studied,
mainly the girls. There was an association between fat patterning
and blood pressure. Children with high body fatness are at
risk for developing high blood pressure. These results raise the
possibility of using fat patterning ratios and BMI as predictors
for hypertension in children.
The financial support received from the South African Medical Research
Council and the University of Limpopo is gratefully acknowledged. Any
opinions, findings and conclusions or recommendations expressed in this
material are those of the authors and therefore the above funding sources do
not accept any liability in regard thereto. The authors are indebted to ELS
administrators (Simon Seleka, William Makata and Jan Mabote) for provid-
ing technical support in the preparation of this manuscript.
References
1.
Kruger HS, Puoane T, Senekal M, van der Merwe M. Obesity in South
Africa: challenges for government and health professionals.
Public
Health Nutr
2005;
8
(5): 491–500.
Table 3. Linear regression coefficients for the association
between systolic and diastolic blood pressure with the sum of
four skinfolds, ST, S/ST and SS/SSTB among Polokwane
private school children aged five to 15 years
Blood
pressure
Unadjusted
Adjusted for age and gender
Beta
p
-value
95% CI
Beta
p
-value
95% CI
Systolic BP
Sum of four
skinfolds
0.29 0.000** 0.26 0.33 0.21 0.000** 0.18 0.24
S/T
14.7 0.000** 10.47 18.95 6.41 0.001* 2.55 10.26
S/ST
42.76 0.000** 29.93 55.59 18.15 0.002* 6.48 29.81
SS/SSTB 62.08 0.000** 49.00 75.17 29.81 0.000** 17.74 41.88
Diastolic BP
Sum of four
skinfolds
0.20 0.000** 0.17 0.23 0.17 0.000** 0.14 0.20
S/T
7.21 0.000** 3.93 10.49 3.33 0.044* 0.08 6.58
S/ST
19.41 0.000** 9.48 29.34 7.81 0.119 -2.003 17.63
SS/SSTB 32.12 0.000** 21.93 42.30 17.50 0.001* 7.33 27.68
**
p
<
0.001; CI
=
confidence interval; ST
=
ratio of subscapular-to-triceps skin-
folds, S/ST
=
ratio of subscapular-to-triceps skinfolds; SSTB
=
ratio of trunk-to-
limb skinfolds; SS
=
trunk ratio.
Table 4.The odds ratio and 95% confidence interval for the association
of over-fatness and high blood pressure among Polokwane private
school children aged five to 15 years
Unadjusted
Adjusted for age and gender
OR
p
-value 95% CI
OR
p
-value 95% CI
High systolic BP 3.23 0.000** 2.31 4.52 3.61 0.000** 2.49 5.24
High diastolic BP 2.83 0.000** 2.04 3.93 2.84 0.000** 2.03 3.98
Hypertension
3.11 0.000** 2.17 4.46 3.29 0.000** 2.22 4.86
**
p
<
0.001; CI
=
confidence interval; OR
=
odds ratio.