CARDIOVASCULAR JOURNAL OF AFRICA • Vol 21, No 3, May/June 2010
AFRICA
149
economical protocol for screening purposes in impoverished
African communities. The aim of this study was, therefore, to
determine which surface anthropometric and MS markers are
associated with the development of microalbuminuria or renal
impairment in black Africans.
Methods
This sub-study is nested in the Sympathetic Activity and
Ambulatory Blood Pressure in Africans (SABPA) study, which
was a multidisciplinary target-population study conducted
in 2008–2009, avoiding seasonal changes. The North-West
Department of Education and the South African Democratic
Teachers Union gave the necessary authorisation for this study
to take place. Participants signed an informed consent form,
which has been approved by the Ethics Committee of the North-
West University (NWU) and the study conformed to the ethical
guidelines of the World Medical Association Declaration of
Helsinki.
16
We included urban black African male (
n
=
101) and female
(
n
=
99) teachers with the same socio-economic status (aged
between 25 and 60 years) from one of the four Dr Kenneth
Kaunda education districts in the North West province, South
Africa. The exclusion criteria were: pregnancy, lactation, high
temperature (
>
37°C), users of
α
- and
β
-blocking agents, users
of psychotropic agents, blood donors or having been vaccinated
in the past three months before taking part in the study.
Collection of data for each participant continued on work-
ing days over a two-day period from February to May 2008.
Participants were brought to the Metabolic Unit research facility
on the NWU campus. The Metabolic Unit consists of bedrooms
for each participant, bathrooms, a kitchen and a dining room
as well as a living room with a television. Here the participants
stayed overnight and fasted from 22:00. The following day at
06:00 the urine samples were collected followed by anthropomet-
ric measurements, which were taken in triplicate. Subsequently,
blood sampling and blood pressure measurements followed.
Equipment, measurements and analyses
Alcohol consumption and cigarette usage was determined by
means of a yes/no response. The physical activity index (PAI)
was determined with the help of the World Health Organisation
Global Physical Activity questionnaire. A low level of activity
is scored when not meeting the criteria of at least 600
+
METS
minutes/week.
Maximum stature was measured with a stadiometer to the
nearest 0.1 cm while the participant’s head was in the Frankfort
plane, the heels together and the buttocks and upper back touch-
ing the stadiometer. Mass was measured to the nearest 0.1 kg on
a Krups scale with the participant wearing minimal clothes and
with the weight evenly distributed. These measurements were
used to calculate body mass index (BMI) by dividing weight (kg)
by height (m
2
).
12
The circumferences were measured with the participant in
a standing position using a non-extensible and flexible anthro-
pometric tape. Firstly, the neck circumference (NC) was taken
immediately superior to the thyroid cartilage perpendicular
to the long axis of the neck.
17
Secondly, the WC was taken at
the midpoint between the lower costal rib and the iliac crest,
perpendicular to the long axis of the trunk.
17
The hip circum-
ference (HC) was taken at the greatest posterior protuberance
of the buttocks perpendicular to the long axis of the trunk.
17
The WHR was calculated using the WC/HC circumferences.
12
Waist-to-height ratio (WHeiR) was calculated by dividing WC
by height.
18
Blood pressure was measured with a sphygmomanometer
using the Riva-Rocci/Korotkoff method
19
on the non-dominant
arm applying the appropriate cuff size for obese and non-obese
persons. Participants rested for 10 minutes in the supine posi-
tion (semi-fowlers) before the first measurement was taken. Two
duplicate measures were taken with a three- to five-minute rest-
ing period between each measurement and the second measure-
ment was used for the MS criteria for BP.
10
A fasting resting blood sample was obtained with a winged
infusion set from the brachial vein branches from the right
arm by a registered nurse. Glucose samples were collected in
sodium fluoride tubes and all MS markers were handled accord-
ing to standardised procedures and stored as serum samples at
–80°C. Analysis was done using the Konelab
TM
20i sequential
multiple analyser computer (SMAC) (Thermo Scientific,Vantaa,
Finland). Urine samples were used to determine the presence
of microalbuminuria. An overnight (eight-hour) fasting urine
sample of 100 ml was obtained after waking. Urine was stored at
4°C after collection and frozen at –80°C. The method involved
measurement of immunoprecipitation enhanced by polyethylene
glycol at 450 nm with the SMAC. HIV status was determined
using antibody screening tests provided by the Department of
Health in the North-West province.
Statistical analysis
Statistical analysis was performed using the Statistica 8 program.
20
Subjects were stratified into two groups based on their WHR (
≤
0.80 and
>
0.80).
11
The prevalence rates were computed using the
two-way Pearson Chi-square analysis. For comparison between
variables, analysis of covariance (ANCOVA) independent of
confounders (age, BMI, PAI, smoking and alcohol consumption)
was done to determine significance. Forward stepwise multiple
regression analyses included MS markers (WC, glucose, TG,
HDL, BP), anthropometric variables (NC) and lifestyle factors
(age, BMI, smoking, alcohol, PAI) as independent variables to
determine associated development of microalbuminuria. Data
were regarded as statistically significant when
p
≤
0.05.
Results
In Table 1, the high-WHR groups were older than their low-
WHR counterparts. As reflected in the data of the total groups,
males (including high-WHR males) were more inclined to
exhibit higher lifestyle risk factors, such as higher prevalence
rates of HIV, smoking and alcohol consumption as well as lower
physical activity in comparison with their female counterparts.
All females could be classified as obese with their higher BMI
and WC values. Most males (including high-WHR groups)
also showed a higher BMI, WC, NC and WHeiR but lower HC
compared to other males and in some instances their female
counterparts.
Both high-WHR gender groups (Table 1) showed increased
levels of BP and impaired fasting glucose (IFG) values [males,
6.34 mmol/l (95% CI: 5.81–6.88) and females, 6.13 mmol/l
(95% CI: 5.37–6.89)]. Microalbuminuria was not present (mean
