36
VOLUME 10 NUMBER 1 • MARCH 2013
DIABETES NEWS
SA JOURNAL OF DIABETES & VASCULAR DISEASE
T
he current global attention directed at
non-communicable diseases (NCDs)
is being driven at the highest levels, with
the World Health Assembly adopting the
important new global target of a 25%
reduction in preventable NCD deaths by
2025 (the 25 by 25 goal). South Africa,
and indeed sub-Saharan Africa, is currently
a melting pot of confounding factors
affecting both risk and prevalence of
chronic diseases of lifestyle, now reaching
epidemic proportions in the developing
world. Addressing social and economic
inequalities among disadvantaged groups,
regulation of the food, drink, alcohol and
tobacco industries, and learning from the
lessons of the HIV and TB epidemics are all
vital to tackling NCDs on a national and
international level.
Further confounding factors in the diag-
nosis and medical management of NCDs
need to be considered in that sometimes
profound differences in risk factors are evi-
dent based on ethnicity and gender. Many
guidelines developed by North American
and European bodies are not necessar-
ily appropriate for use in the developing
world. South African publications in the
international literature consider some of
these concerns.
Urban black women at greater
risk of chronic heart failure with a
younger age of onset
Changing dietary habits and consequent
nutritional deficiencies are having a
significant impact on the health status
of individuals living with chronic heart
failure (CHF) in Soweto (see interview with
Dr Pretorius, p 36). Interesting findings
of Dr Pretorius’ study can be seen in the
demographic profile of the Sowetan
population living with heart failure.
1
Contrary to European findings, in an
urban cohort of blackAfricans, morewomen
present with CHF than men. Furthermore,
the mean age of onset for women is lower
than for men in the Soweto study, as well
as occurring at a younger age (5–10 years)
than in European counterparts.
1.
Pretorius S. The impact of dietary habits and
nutritional deficiencies in urban African patients
living with heart failure in Soweto, South Africa
– A review.
Endocrin Metab Immune Disord Drug
Targets
2013:
13
(1). Jan 15 [Epub ahead of print].
Population-specific cut-off points
proposed for diagnosis of the
metabolic syndrome in South Africa
Nigel Crowther and Shane Norris of the
Witwatersrand University’s Departments of
Chemical Pathology and Paediatrics ques-
tion the appropriateness of the European
guidelines used for the diagnosis of the
metabolic syndrome in sub-Saharan African
women. Their study measured the preva-
lence of obesity and related metabolic disor-
ders in an urban population of black women
to determine the appropriate waist cut-off
point for diagnosing metabolic syndrome.
1
Of 1 251 African females from the Birth
to Twenty cohort in Soweto, prevalence of
obesity, T2D and the metabolic syndrome
were 50.1, 14.3 and 42.1%, respectively. The
appropriate waist cut-off point was found to
be 91.5 cm (currently recommended levels
are 80.0 cm) and was similar to the cut-off
points obtained for detecting increased risk
of insulin resistance (89.0 cm), dyscglycaemia
(88.4 cm), hypertension (90.1 cm), hypo-
high-density lipoproteinaemia (87.6 cm)
and hyper-low-density lipoproteinaemia
(90.5 cm). The similar waist cut-off points
identified for the detection of the individual
components of the metabolic syndrome
and related cardiovascular risk factors
demonstrates that the risk for different
metabolic diseases increases at the same
level of abdominal adiposity, suggesting a
common aetiological pathway.
Salome Kruger and colleagues from
the Centre of Excellence for Nutrition at
the North West University’s Potchefstroom
campus propose a cut-off point of waist-to-
height ratio (WHtR) of 0.41 for metabolic
risk in African township adolescents.
2
It has
previously been proposed that a WHtR > 0.5
be the cut-off point for abdominal obesity
in both genders and all ages. To date it is
unknown if this cut-off point is appropriate
for previously undernourished adolescents.
Assessment of the cut-off value of WHtR
associated with increased metabolic risk
was performed in 178 black South African
adolescents aged between 14 and 18 years.
The WHtR cut-off points ranged from 0.40
to 0.41, with best diagnostic value at 0.41.
A WHtR of 0.40 had 80% sensitivity and
38.5% specificity to classify fasting blood
glucose > 5.6 mmol/l. A WHtR of 0.41 had
64% sensitivity and 58.5% specificity for a
HOMA-IR > 3.4; 55% sensitivity and 55.6%
specificity for a high-sensitivity C-reactive
protein level > 1 mg/l; and a 64% sensitivity
and 50.2% specificity for a blood pressure
higher than the age-, gender-, and height-
specific 90th percentiles.
1.
Crowther NJ and Norris SA. The current waist
circumference cut point used for the diagnosis of
metabolic syndrome in sub-Saharan African women
is not appropriate.
PLOS ONE
2012; 7(11): e48883.
2.
Kruger HS, Faber M, Schutte AE, Ellis SM. A
proposed cutoff point of waist-to-height ratio for
metabolic risk in African township adolescents.
Nutrition
2013;
29
(3): 502–507.
South African studies in the international literature: considerations of
ethnicity and gender in chronic diseases of lifestyle
‘Various misperceptions need to be
corrected. Not only is the notion widespread
that obesity is not a problem, but the myth
persists that it is actually desirable. For
many recently urbanised people, gaining
weight is a sign that they can now afford
to eat better than before and that they are
able to feed their children foods that they
themselves were denied in childhood. In
addition, not being thin is often interpreted
as evidence that an individual is not HIV
positive. We have a lot of work ahead of
us if we are to successfully address the
increasing incidence in this population of
diseases of lifestyle and the risk factors for
them’, she concluded.
P Wagenaar
1.
Pretorius S. The impact of dietary habits and nutritional
deficiencies in urban African patients living with heart
failure in Soweto, South Africa – A review.
Endocrin
Metab Immune Disord Drug Targets
2013;
13
(1). Jan
15 [Epub ahead of print].
2.
Stewart S, Carrington MJ, Pretorius S, Ogah OS,
Blauwet L, Antras-Ferry J, Sliwa K. Elevated risk factors
but low burden of heart disease in urban African
primary care patients: A fundamental role for primary
prevention.
Int J Cardiol
2012;
158
(2): 205–210.
doi:10.1016/j.ijcard.2011.01.022. Epub 2011 Feb 24.
