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VOLUME 12 NUMBER 1 • JULY 2015
35
SA JOURNAL OF DIABETES & VASCULAR DISEASE
RESEARCH ARTICLE
Prevalence of the metabolic syndrome and determination of
optimal cut-off values of waist circumference in university
employees from Angola
PEDRO MAGALHÃES, DANIEL P CAPINGANA, JOSÉ G MILL
Correspondence to: Pedro Magalhães
Department of Physiology, Faculty of Medicine, University Agostinho
Neto, Luanda, Angola
e-mail:
pedromagalhaes24@hotmail.comDaniel P Capingana, José G Mill
Department of Physiology, Federal University of Espírito Santo, Vitoria,
Brazil
Previously published in
Cardiovasc J Afr
2014;
25
(1): 27–33
S Afr J Diabetes Vasc Dis
2015;
12
: 35–40
Abstract
Background:
Estimates of the prevalence of the metabolic
syndrome in Africans may be inconsistent due to lack of
African-specific cut-off values of waist circumference (WC).
This study determined the prevalence of the metabolic
syndrome and defined optimal values of WC in Africans.
Methods:
This cross-sectional study collected demographic,
anthropometricandclinicaldataof615Universitaryemployees,
in Luanda, Angola. The metabolic syndrome was defined
using the third report of the National Cholesterol Education
Program Adult Treatment Panel (ATPIII) and the Joint Interim
Statement (JIS) criteria. Receiver operating characteristics
curves were constructed to assess cut-off values of WC.
Results:
The crude prevalence of the metabolic syndrome
was higher with the JIS definition (27.8%, age-standardised
14.1%) than with the ATP III definition (17.6%, age-
standardised 8.7%). Optimal cut-off values of WC were 87.5
and 80.5 cm in men and women, respectively.
Conclusions:
There was a high prevalence of the metabolic
syndrome among our African subjects. Our data suggest
different WC cut-off values for Africans in relation to other
populations.
Keywords:
metabolic syndrome, waist circumference, Africans,
Angola
The metabolic syndrome is characterised by the presence of multiple
metabolic risk factors for cardiovascular (CV) disease
1
and type 2
diabetes mellitus.
2
In clinical practice, the metabolic syndrome
is diagnosed by combinations of three or more of the following
five risk factors: central obesity, elevated blood pressure, glucose
intolerance, hypertriglyceridaemia and low high-density lipoprotein
cholesterol (HDL-C).
3-6
Worldwide the prevalence of the metabolic syndrome is
increasing and becoming a pandemic, and this increase has been
mainly attributed to sedentary lifestyle and obesity.
7
However,
levels of prevalence may vary greatly according to cut-off points of
diagnostic criteria and the ethnic group studied.
8
In sub-Saharan Africa, the majority of countries are experiencing
a rapid demographic and epidemiological transition.
9,10
Available
information from studies in African populations reported a
prevalence of the metabolic syndrome ranging from 0 to as high as
about 50% or more, depending on the population setting.
11
These
data however, are limited to some countries,
12-21
since there are no
available data for the majority of African countries.
Angola is a country in sub-Saharan Africa, which in last few years
has undergone significant political changes, accompanied by a
rapid economic growth and increased urbanisation. These changes
may imply the increasing prevalence of factors contributing to the
metabolic syndrome, such as obesity, insufficient physical activity,
dyslipidaemia, high blood pressure and glucose intolerance.
However, the prevalence of the metabolic syndrome and which
factors contribution more to its occurrence in the Angolan
population remain unknown.
Despite the efforts of several organisations to regulate the
algorithm for a definition of the metabolic syndrome,
3-5
there
is inconsistency on cut-off levels of waist circumference (WC)
for defining the metabolic syndrome in several populations. The
International Diabetes Federation (IDF)
5
recommended the use of
ethnic or country-specific cut-off values of WC for the majority
of populations, a recommendation reinforced in the Joint Interim
Statement (JIS),
7
which tried to define different criteria for a
definition of the metabolic syndrome.
These cut-off values were defined using different methods. For
example, Western countries derived their cut-off values of WC from
a correlation with body mass index (BMI),
4,22
whereas Asian groups
tried to define WC cut-off values yielded by receiver operating
characteristics (ROC) curve analyses.
23
Due to a lack of specific
data from African populations, cut-off points of WC derived from
the European population have been recommended,
5,7
although
emerging data suggest that African-specific cut-off values would be
different from the European cut-off points currently recommended
by the IDF.
18,24,25
Therefore, definition of a more reliable cut-off point
for WC is needed to build a consistent tool for diagnosis of the
metabolic syndrome in sub-Saharan African populations.
The aim of this study was to determine the prevalence of the
metabolic syndrome in a sample of Africans from Angola, using
either the third report of the National Cholesterol Education Program
Adult Treatment Panel (ATP III)
4
or the JIS
7
criteria. Additionally, this
study tried to identify threshold WC levels that best predict other
components of the metabolic syndrome.
Methods
This was a cross-sectional study on cardiovascular (CV) risk factors,
conducted from 2009 to 2010 in employees of a public university
in Luanda, Angola. Participants aged 20 years and older (
n
= 625)
attended to the Department of Physiology, Faculty of Medicine of