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SA JOURNAL OF DIABETES & VASCULAR DISEASE
RESEARCH ARTICLE
VOLUME 16 NUMBER 2 • NOVEMBER 2019
75
corresponds with an increase in BMI, and changes in body fat
composition and distribution, while in boys it is a period of fat loss
and muscle development,
16
thus explaining the differences in BMI,
WC, TFM and WHtR between boys and girls.
Several studies have shown an association between BMI and
blood pressure.
17,18
A Brazilian study showed that overweight and
obese children had a 3.6-fold greater risk of having higher SBP
and 2.7-times increased risk for higher DBP.
19
Both SBP and DBP as
well as PP were higher in the girls than boys. The growth spurt of
puberty, which is often accompanied by a rise in blood pressure,
20
occurs earlier in girls than in boys, thus explaining the higher
blood pressure in girls.
The current study showed a difference in the prevalence of
hypertension and pre-hypertension when overweight/obesity
was classified as the fourth quartile of WC, TFM and WHtR. An
increased WC is a known risk for metabolic diseases in both
children
21
and adults. We have previously shown that BMI, TFM,
WC and WHtR correlated similarly with SBP and PP in females,
although these relationships were different in males. These results
further strengthen the suggestion that the 10- to 14-year-old
girls involved in the study were mostly pubertal and therefore
increased adiposity contributed to higher blood pressure in the
girls. Furthermore, another study showed that children who
had low BMI but high WC were at great risk of developing
hypertension.
22,18
Our results show that children with WC and HC greater than
the 75th percentile had an increased relative risk (1.7 and 1.5,
respectively) of being hypertensive. This finding was confirmed by
the fact that both pre-hypertension and hypertension were over
1.5 times more prevalent in 10- to 14-year-old girls compared to
age-matched boys. On the other hand, higher BMI did not confer a
significant risk of higher BP. However when subjects were separated
into quartiles for BMI, WC, TFM and WHtR, it was noted that SPB,
DBP and PP were significantly higher in boys and girls in the fourth
quartile, indicating that adiposity contributes to blood pressure
levels.
Although the fourth quartile of all measures of adiposity
had significantly higher SBP, DBP and PP, only WC conferred a
significantly (
p
< 0.001) greater risk (1.7 times) for hypertension.
This finding is in agreement with Dong
et al.
,
17
who highlighted the
importance of increased WC on the risk of hypertension in children.
The retrospective study of data from the NHANES study showed
that WC was associated with higher blood pressure in children and
adolescents.
23
Conclusion
This study demonstrates that the prevalence of hypertension and
pre-hypertension was higher in 10- to 14-year-old girls than boys.
The relative risk of having hypertension in this study cohort was
greater in children who had larger WC. The linear relationship
between blood pressure and BMI, WC, TFM and WHtR in
children was weak. However, SBP, DBP, PP and mean arterial
pressure increased with increasing quartiles of BMI, WC, TFM and
WHtR. Consequently, the greatest prevalence of hypertension
and pre-hypertension was in overweight and obese children,
therefore confirming the role of increasing levels of adiposity in
the prevalence of hypertension and pre-hypertension in 10- to
14-year-old children in the Eastern Cape.
Financial support for this work was received from the NRF grant
no: 106066 and 82177 and the Walter Sisulu University Research
Fund. The findings expressed in this article are those of the authors.
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