CARDIOVASCULAR JOURNAL OF AFRICA • Vol 22, No 6, November/December 2011
304
AFRICA
Definition of the metabolic syndrome
To define the metabolic syndrome, the criteria as set out in the
National Cholesterol Education Program (NCEP): expert panel
on detection, evaluation, and treatment of high blood cholesterol
in adults (Adult Treatment Panel III) (ATP III, 2001),
6
followed
by the ATP III as modified in 2005,
7
were used, plus the modified
version specific to the people of south Asian origin (ATP III SAS
2009).
8-10
These criteria were as follows:
•
waist circumference: male
>
90 cm; female
>
80 cm
•
triglycerides:
≥
2.25 mmol/l
•
HDL: male
<
1.03 mmol/l; female
<
1.29 mmol/l
•
blood pressure: SBP
≥
130 mmHg and/or DBP
≥
85 mmHg
•
fasting blood glucose:
≥
5.56 mmol/l.
Statistical analyses
Parameters were expressed as mean and standard deviation
(SD), separately for males and females in the study population.
The prevalence (%) of the MS and its confounding factors were
calculated using standard cut-off values. All statistical analyses
were performed using SPSS (PC
+
version 10.0).
Results
The mean and standard deviation by gender of obesity values,
lipid profiles and blood pressure is presented in Table 1. It was
observed that males had significantly (
p
<
0.05) higher mean
total cholesterol and fasting blood glucose values (
p
<
0.01) than
females.
The difference in prevalence of the MS according to the three
definitions is presented in Table 2. Using the original ATP III
(2001) definition, the overall prevalence of the MS in the study
was found to be 32.3%. However, according to the ATP III
modified criteria (2005), the prevalence was found to be 48.3%
among the participants. When the south Asian-specific cut-off
values were taken into consideration, the prevalence was found
to be 31.4%.
Out of five confounding factors, the three factors playing a
crucial role were high abdominal obesity (61.1%), low HDL
cholesterol (50.9%) and high blood pressure (63.7%). It was also
observed that for all three definitions (NCEP ATP III 2001, ATP
III modified 2005, and ATP III SAS 2009), female participants
had a considerably higher prevalence of the MS compared to
male subjects (Fig. 1).
Discussion
It was observed that the prevalence of the MS was different,
depending on the three definitions used. Moreover, the preva-
lence of elevated triglyceride levels (hypertriglyceridaemia),
which is a distinctive feature of people of Indian origin, varied
considerably in the study population owing to the use of the
south Asian-specific cut-off value for elevated triglycerides. The
marked difference in the overall prevalence of the MS from the
ATP III (2005) definition to the SAS (2009) definition (48.3 vs
31.4%) was due to the use of the south Asian-specific cut-off
values for WC and triglyceride levels. Importantly, whether the
modified ATP III (2005) or the revised SAS (2009) definition is
used, a large number of individuals are likely to be misclassified
due to lack of a common minimum criterion required to better
comprehend the problem of the MS among Asian Indians.
Several other studies have shown such discrepancies, not only
in the Indian population but also in other Asian countries, such
as China and Iran. In a study from India,
10
the World Health
Organisation (WHO), ATP III and IDF criteria of the MS identi-
fied a differential prevalence of the MS in the study population.
The WHO criteria identified a greater number of coronary artery
disease (CAD) subjects in males, but not in females.
10
Studies pertaining to Asian Indians revealed that the ATP III
criteria identified a significantly higher proportion of people
with the MS compared with the WHO criteria.
11,12
It was
mentioned that lower cut-off values of WC and BMI to define
the MS might be critical for the accurate assessment of the MS
among Asian Indians. Moreover, inclusion of BMI and making
WC a non-obligatory criterion, more cases of the MS were
detected. However, for Asian Indians, making WC a mandatory
TABLE 2. PREVALENCE (%) OF METABOLIC SYNDROME
PHENOTYPES BY DEFINITIONS
Factors
ATP III 2001 ATP III 2005 SAS 2009
Waist circumference (cm)
30.9
61.1
61.1
Triglycerides (mmol/l)
39.7
39.7
2.3
High-density lipoprotein (mmol/l)
50.9
50.9
50.9
Blood pressure (mmHg)
63.7
63.7
63.7
Fasting blood glucose (mmol/l)
10.0
21.7
21.7
Metabolic syndrome (%)
32.3
48.3
31.4
SAS
=
South Asian specific.
TABLE 1. DESCRIPTIVE STATISTICS OF THE STUDY
POPULATION (
n
=
350)
Variables
Male (
n
=
184) Female (
n
=
166) Total (
n
=
350)
Mean SD Mean SD Mean SD
Age (years)** 54.04 12.40 48.48 11.57 51.40 12.31
BMI (kg/m2)
22.37 4.09 23.20 4.37 22.76 4.24
WC (cm)
89.81 10.04 88.90 9.69 89.38 9.87
SBP (mmHg)
132.97 24.02 137.21 24.52 134.98 24.31
DBP (mmHg)
82.22 11.41 83.48 10.55 82.82 11.01
TC (mmol/l)*
2.23 0.31 2.24 0.26 2.27 0.29
TG (mmol/l)
1.61 0.30 1.57 0.25 1.59 0.28
HDL (mmol/l)
1.13 0.12 1.13 0.11 1.13 0.12
LDL (mmol/l)
3.39 0.70 3.25 0.59 3.32 0.65
VLDL (mmol/l)
0.32 0.006 0.31 0.005 0.31 0.005
FBG (mmol/l)** 5.17 1.30 4.92 0.93 5.05 1.15
BMI
=
body mass index; WC
=
waist circumference; WHR
=
waist–hip
ratio; SBP
=
systolic blood pressure; DBP
=
diastolic blood pressure; TC
=
total cholesterol; TG
=
triglyceride; HDL
=
high-density lipoprotein; LDL
=
low-density lipoprotein; VLDL
=
very low-density lipoprotein; FBG
=
fasting blood glucose.
Significant gender difference at *
p
<
0.05; **
p
<
0.01.
Fig. 1. Prevalence of the metabolic syndrome by defini-
tions and gender.
70
60
50
40
30
20
10
0
%
ATP III
2001
ATP III modified
2005
ATP III SAS
2009
Female
Male
