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CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 2, March 2013
36
AFRICA
African context and has been declared by the African Union as
one of the greatest health challenges to the continent other than
HIV/AIDS. The problem is compounded by lack of awareness,
frequent under-diagnosis, low levels of control and the severity
of its complications.
11-13
Despite the dearth of data and marked variation between
and within studies, hypertension is estimated to affect 10 to
30% of Africans, virtually one in six people. In West Africa,
hypertension affects 30 to 40% of people aged 65 years or older
in rural areas, and approximately 50% of semi-urban dwellers.
In the mixed population (Coloureds) of South Africa, 50 to 60%
of people over the age of 65 years have hypertension. These
figures approximate the 60 to 70% prevalence of hypertension in
African-Americans over 65 years of age.
14
An estimated 75 to 80
million Africans, more than twice the global estimate of people
with HIV/AIDS, had hypertension in 2000. The number of
Africans with hypertension will escalate to 150 million by 2025.
15
The rising prevalence of hypertension in rural settings is of
great concern and probably relates to the rapid ‘urbanisation’
of rural dwellers.
15,16
About 40% of Africans with hypertension
are undiagnosed, less than 30% of those who are diagnosed
with hypertension are on treatment, and less than 20% of those
on treatment have optimal blood pressure control (
<
140/
<
90
mmHg).
13,17-21
Diabetes mellitus and impaired glucose tolerance
In 2010, an estimated 12.1 million people with diabetes mellitus
(4.2% of the global estimate of 285 million) were in sub-Saharan
Africa.
22
The following year, diabetes prevalence rose to 14.7
million (4.02% of the global 366 million). By the year 2030, there
will be a 90% projected increase in diabetes prevalence in SSA,
bringing the number of Africans with diabetes to 28 million.
23
Nearly 78% of people with diabetes in sub-Saharan Africa
are undiagnosed. Heavily populated countries such as Nigeria
have three million diabetics, followed by South Africa with 1.9
million.
Fuelling the diabetes epidemic is a large pool of people
with impaired glucose tolerance (IGT), totalling an estimated
26.9 million in 2010, and expected to rise to 47.3 million
by 2030. Diabetes is associated with a pro-coagulant state,
compounding the commonly accompanying insulin resistance
and hyperinsulinaemia, and thus contributing to accelerated
atherogenesis.
Although diabetes mellitus and pre-diabetes are important
cardiovascular risk factors globally, their roles in populations
undergoing rapid epidemiological transition are unclear.
Atherosclerotic complications of diabetes are likely determined
by the pace and degree of affluence, genetic factors, phenotypic
heterogeneity of type 2 diabetes, changes in life expectancy, and
burden, duration and contribution of other cardiovascular risk
factors such as hypertension, dyslipidaemia and tobacco use. In
many parts of SSA, micro-angiopathies are the dominant chronic
complications of diabetes,
24-30
unlike in the Western world, where
macrovascular complications (MAC) predominate.
Overweight and obesity
Estimates of the prevalence of overweight and obesity vary
widely across SSA, but it is generally higher in females than
in males and particularly in southern Africa, Mauritius and
Seychelles, compared to the rest of the continent. In East and
Central Africa the prevalence of overweight (body mass index
from
>
25 to
<
30 kg/m
2
) in women is two to three times higher
than in men (Table 1). In Ghana, males appear to be more
overweight than women. However, in much of West Africa,
southern Africa and in the islands off the east coast of Africa,
the prevalence of overweight in men is approximating that of
females. This trend towards parity indicates that overweight is
now a widespread continental problem in populations of SSA
above the age of 15 years.
However obesity still has relatively low prevalence rates
throughout SSA, ranging between 1.1 and 43.2% in females and
0.1 and 21.3% in males. Populations of southern Africa and the
islands of Mauritius and Seychelles exhibit a greater prevalence
of obesity, particularly among the women.
Physical inactivity
There are scant data on the prevalence of physical inactivity
in SSA. A WHO report of national surveys in both urban and
rural settings in five African countries (Ethiopia, Republic of
Congo, Ghana, South Africa and Zimbabwe) in 2003, involving
a total of 14 725 individuals aged 18 to 69 years revealed a mean
prevalence of physical inactivity in 19.6% of men and 22.9% of
women.
31
Physical inactivity was defined using the International
Physical Activity Questionnaire (IPAQ). IPAQ inactive is defined
as not meeting any of the following three criteria: three or
more days of vigorous activity of at least 20 minutes per day,
accumulating at least 1 500 MET-min per week, OR five or
more days of moderate-intensity activity or walking of at least
30 minutes per day, OR five or more days of any combination
of walking, moderate-intensity or vigorous-intensity activities,
achieving a minimum of at least 600 MET-min per week.
Across the continent, low levels of physical activity are
reported in women compared to men. According to the WHO
survey, a greater number of lazy people are found in southern
TABLE 1. PREVALENCE OF OVERWEIGHTAND OBESITY
IN FEMALESAND MALESAGED 15YEARSAND OLDER IN
SELECTEDAFRICAN COUNTRIES BY REGION, 2011
Region/country
Overweight
(BMI > 25 kg/m
2
, < 30 kg/m
2
)
Obesity
(BMI > 30 kg/m
2
)
Females (%)
Males (%) Females (%) Males (%)
Eastern Africa
Uganda
UR Tanzania
23.9
28.7
8.2
16.8
1.9
3.6
0.1
0.8
Central Africa
DR Congo
Rwanda
15.8
20.7
5.7
8.1
1.1
1.6
0.1
0.1
Western Africa
Nigeria
Ghana
36.8
32.5
26.0
35.6
8.1
5.9
3.0
4.8
Southern Africa
Botswana
South Africa
53.5
68.5
41.6
41.3
17.7
36.8
6.9
7.6
Islands
Mauritius
Seychelles
56.8
73.8
44.8
63.8
22.3
43.2
8.0
21.3
DR Congo
=
Democratic Republic of Congo, UR Tanzania
=
United Republic
of Tanzania.
World Health Organisation: WHO Global Infobase:
https://apps.who.int/
infobase/Comparisons.aspx (Accessed 28 December 2011). Database updated
20/01/2011. Accessed 28 December 2011.