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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 6, November/December 2020
314
AFRICA
Determination of optimal cut-off values for waist
circumferences used for the diagnosis of the metabolic
syndrome among Batswana adults (ELS 32)
DM Tladi, L Mokgatlhe, S Shaibu, T Nell, R Mitchell, CJ Mokgothu, T Gabonthone, O Hubona
Abstract
Background:
To date, no definitive waist circumference (WC)
cut-off values for abdominal obesity (AO) have been estab-
lished for sub-Saharan Africa, including Botswana. Therefore,
the classification of AO among these populations is based on
European values. For accurate diagnosis of the metabolic
syndrome (MetS), cut-off values reflective of the population
investigated must be used.
Objective:
The study was an attempt to determine optimal
cut-off values for AO among Batswana adults.
Methods:
The receiver operating characteristic curve was used to
determine the optimal cut-off values for predicting at least two
other risk factors of the MetS. Data were used from a descrip-
tive cross-sectional study employing a complex multi-stage clus-
ter sampling. Demographic and anthropometric measurements
(weight and height, waist and hip circumferences), blood pres-
sure, and blood glucose, triglycerides, high-density lipoprotein
cholesterol and total cholesterol levels were collected from 384
men and 416 women in Gaborone and the surrounding villages.
Results:
The ability of waist circumference to predict at least
two other risk factors of the MetS gave cut-off values of ≥ 91.0
cm (sensitivity 69.1% and specificity of 90.8%, area under the
curve 0.85) for men and ≥ 82.3 cm (sensitivity of 88.6% and
specificity of 58.9%, area under the curve of 0.76) for women.
Conclusion:
There is a difference between the cut-off values
for Europeans with those determined for Batswana adults.
Inconsistencies in cut-off values used have the potential for unde-
sirable consequences for cardiovascular risk stratification and
prioritisation of preventative strategies for AO and the MetS.
The need to determine population-, ethnic- and gender-based
cut-off values for AO for Batswana adults has never been more
paramount.
Keywords:
metabolic syndrome, Batswana adults, abdominal
obesity, waist circumference, cut-off values.
Submitted 12/4/18, accepted 7/7/20
Cardiovasc J Afr
2020;
31
: 314–318
www.cvja.co.zaDOI: 10.5830/CVJA-2020-025
Modernisation and urbanisation of African countries
accompanied by sedentary lifestyles and the nutritional transition
have resulted in increased obesity among African populations.
Obesity is reported to have increased in sub-Saharan African
(SSA) countries, with the southern African region being the most
affected.
1
A high prevalence of obesity among Batswana adults
has also been reported by several groups recently, especially
among the women.
2-4
Abdominal obesity (AO), in particular, is associated with
the development of a number of metabolic disorders such
as dyslipidaemia and disglyceraemia, some occurring at the
same time as the metabolic syndrome (MetS). However, the
distribution of fat storage, rather than overall excess body fat,
especially visceral body fat, plays an important role in these
associations
5, 6
and varies between white and black populations.
7,8
According to the International Diabetes Federation (IDF)
definition of the MetS, an individual has to have AO and any
two other risk factors, such as low high-density lipoprotein
cholesterol (HDL-C), high triglyceride levels (TG), elevated
blood pressure (BP) and increased fasting blood glucose (BG)
level.
9
The pathogenesis of the MetS and each of its individual
components is complex and is not fully understood, however,
two components appear to stand out as potential causative
factors, namely insulin resistance and AO. The IDF definition
has since elevated AO to be the determining factor for the MetS
diagnosis, the rationale for this requirement being that AO is
more strongly correlated with other MetS features than any
other component.
10
Therefore, defining AO accurately is of great
importance for a proper diagnosis of the MetS, along with other
cardiometabolic risk factors.
AO is generally assessed by measuring waist circumference
(WC), which has been found to be ethnic specific,
8,11
suggesting
that different cut-off points for different ethnic groups should
be used for a proper diagnosis of AO. For example, some ethnic
groups, such as Asians, have been reported to be more likely
to develop complications of the MetS at a much lower WC
compared to Caucasians.
9,12
Different cut-off points for different ethnic groups have
therefore been established. For instance, European cut-off points
are ≥ 80 cm for women and ≥ 94 cm for men, South Asians
and Chinese are ≥ 80 cm for women and ≥ 90 cm for men, and
Department of Physical Education, Health and Recreation,
University of Botswana, Gaborone, Botswana
DM Tladi, PhD,
tladidm@UB.AC.BWR Mitchell, MHMS
CJ Mokgothu, PhD
T Gabonthone, MSc
O Hubona, MEd
Department of Statistics, University of Botswana,
Gaborone, Botswana
L Mokgatlhe, PhD
Department of Physiological Sciences, Stellenbosch
University, Stellenbosch, South Africa
T Nell, PhD
School of Nursing, University of Botswana, Gaborone,
Botswana
S Shaibu, PhD