CARDIOVASCULAR JOURNAL OF AFRICA • Vol 21, No 3, May/June 2010
AFRICA
151
<
20 mg/l). High systolic (SBP) and diastolic blood pressure
(DBP), as risk factors for the MS (SBP
>
140 mmHg, DBP
>
90 mmHg
11
), was present in both high-WHR groups. The high-
WHR and total male groups presented TG values that constituted
a MS risk factor (
>
1.7 mmol/l).
10
All groups presented with
favourable HDL profiles (males
≥
0.91 mmol/l and females
≥
1.01 mmol/l).
10
In Table 2, multiple linear regression analysis showed that the
development of microalbuminuria was explained by only high
vascular BP in overweight males, and by high vascular BP, TG
and WC in all males. In high-WHR females, microalbuminuria
was explained by increases inWC, while only NC was associated
with microalbuminuria development in all females.
Discussion
The main aim of this study was to determine the best surface
anthropometric parameters in Africans to have an association
with development of the MS and microalbuminuria. In terms of
lifestyle factors, it was found that the whole population had a
tendency towards lower physical activity, which was associated
with increased body weight and urbanisation.
3,8
Inactive lifestyle
and cigarette smoking are two of the risk-stratifying factors that
have been set forth by the ASCM
12
and Berger and Marais.
22
Alcohol consumption is also known to increase BP and blood
glucose levels and the risk of kidney failure, all of which are risk
factors for the MS.
23
Alcohol consumption was high in the male
population, which could possibly explain its contribution to the
development of these risk factors.
Urbanised Africans are more prone to being overweight or
obese.
2,3
Obesity was even more prevalent in the female than the
male population. One reason for this difference could be attribut-
ed to the gender hormones. In males, testosterone is responsible
for the high muscle mass-to-fat mass ratio,
24
whereas oestrogen is
responsible for fat distribution in females.
24
Females also need a
greater body fat percentage in order to maintain healthy living.
12
Furthermore, the high prevalence of obesity among African
females reflects their belief that overweight and obesity indicate
their health status and the wealth of their spouses.
25
The high rate
of overweight and obesity found among African females in our
study was consistent with the findings of Kruger
et al
.
26
and Croft
et al.
,
27
which stated that anthropometric measures were higher in
African-American females compared to Caucasian females.
Additionally, high HC in females could be accounted for by
their gynoid fat distribution.
28
In this study, however, the females
presented rather with a high WC. WC often increases with the
number of births,
5
and in older females, high WC can be a result
of menopause, which changes fat distribution patterns to the
android pattern.
28
Younger females’ WC can also be attributed
to water retention due to various hormonal changes during the
menstrual cycle.
29
Conway
et al
.
30
found that WC rather than WHR should be
used as measures of risk in Africans. Our study supports the
finding that WC should be used, as this was positively associated
with the development of microalbuminuria in males and females.
Further analysis in all females (independent of obesity levels)
additionally showed that NC could be used as an indicator of the
development of target-organ damage or microalbuminuria. NC
was related to other anthropometric parameters, which showed a
relationship with metabolic disorders.
31,32
The risk for development of the MS was further strengthened
by the higher blood glucose levels found in both high-WHR
gender groups, suggesting IFG values. Increased blood glucose
levels could be due to increased insulin resistance resulting from
increased accumulation of central body fat and the metabolic
nature of this fat.
3,33
Gender hormones have been found to affect
the WC and blood glucose levels in both males and females,
34,35
however, when testing for the development of microalbuminuria,
glucose values did not reach significance.
In the high-WHR males, only vascular BP responses were
associated with the development of microalbuminuria but in
all males, the MS markers, TG and WC were also associated
with increased health risk. In previous studies, we showed that
the urban African male from the North-West province of South
Africa has increased vascular BP and blood glucose levels.
4
These findings have been associated with poorer physiological
well being and coping with adversity in an urban environment.
4
It has been suggested that a universal cut-off value for WHR
not be used and that this value should differ between age and
race groups.
36
The IDF suggested that European data should
be used when screening Africans until effective cut-off values
can be developed for this population. Our study suggests that
WC in males and females, as well as NC be used as a predic-
tor of cardiometabolic risk in the African population and that
Africans can be healthy and obese. African females believe that
fatness reflects health,
25
and this perceived psychological well
being could contribute to actual physiological well being, possi-
bly explaining the healthy obesity that was seen in our study.
Another reason could be that some of the risk factors are hetero-
geneous and multifactoral;
37
therefore anthropometry can be seen
as part of the underlying cause and is not directly associated with
disease prevalence.
Although neither of the groups were classified as presenting
with microalbuminuria (
>
20 mg/l urine), the development of
renal impairment may occur as a complication of diabetes
6,7,38
and
obesity.
36
Our study did not support this notion as we revealed only
an associated trend between the development of microalbuminu-
ria and anthropometric markers, i.e. WC in all groups and NC in
females. The measured microalbuminuria levels could, however,
be distorted in a random urine sample by the effects of urinary
concentration and therefore a microalbuminuria:creatinine ratio
is a preferable measure to lessen the variability of urine concen-
trations.
39,40
A limitation to this study could be that the observed results
were not monitored over time to determine the effect of increased
or decreased anthropometric measurements on the measured
physiological markers, and a follow up is recommended. In order
to identify WC cut-off values for Africans, we recommend a
comparison of NC, MS markers and development of microalbu-
minuria in WC quartiles.
Conclusion
Vascular BP, blood triglyceride levels and WC were associated
with risk of renal impairment in males, whereas in females, NC
and WC circumferences were associated with this risk.
The authors gratefully acknowledge the assistance of all members of the
SABPA research team, especially C Lessing (RN) and S Péter (MD), and the
participants for their involvement in this study. Funding was obtained from
the North-West University, Potchefstroom Campus; the National Research
Fund, South Africa; and the Metabolic Syndrome Institute, France.
