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AFRICA
CVJAFRICA • Volume 26, No 2, H3Africa Supplement, March/April 2015
crude prevalence of hypertension increased from one to 4%.
According to Adedoyin
et al.
, up to 36.6% of adult Nigerians
were hypertensive in 2008.
67
The impact of migration from rural to urban areas was
demonstrated in a longitudinal study in Kenya, in which moving
from a rural to an urban setting produced significant increases
in blood pressure within a short time. Growing migration from
rural to urban areas also portends a worsening prevalence of
hypertension as migrants adopt lifestyle changes in physical
activity, dietary habits and stress levels. Regardless of gender
or type of community, advancing age is associated with an
increased prevalence of hypertension, and this implies a greater
burden of hypertension (and indeed stroke)
68
as population aging
occurs in Africa.
67-69
Several surveys have demonstrated a very low prevalence
of hypertension awareness and control (BP
<
140/90 mmHg)
in Africa. In Tanzania, slightly less than 20% of hypertensive
subjects were aware of their diagnosis, approximately 10% of
them were treated, and
<
1% were controlled.
70
A survey in
Ghana showed that 34% were aware of their condition, of whom
18% were treated and only 4% were controlled. However, in the
United States, 69% of hypertensive subjects were aware of their
diagnosis, 58% of them were treated, and 31% were controlled.
70
The low prevalence of awareness, treatment, and control of
hypertension poses a serious challenge for stroke prevention in
Africa.
70
This scenario also applies to several other NCDs such
as diabetes mellitus and dyslipidaemia, which are on the increase
in Africa.
66
Type 2 diabetes mellitus
According to International Diabetes Federation (IDF), the
current estimated prevalence rate of type 2 diabetes in Africa
is about 2.8%. Countries such as Malawi and Ethiopia have
rates under 2%, whereas Ghana, Sudan and South Africa have
prevalence rates over 3%.
66
Currently, there are 10.4 million
individuals with diabetes in sub-Saharan Africa, representing
4.2% of the global population with diabetes. By 2025, it is
estimated that this figure will have increased by 80% to reach
18.7 million in this region, with a higher prevalence in the urban
areas.
66
Studies indicate that an aging population, coupled
with rapid urbanisation, is expected to lead to the increasing
prevalence of diabetes in Africa.
66
Dyslipidaemia
Dyslipidaemia has emerged as an important risk factor in
Africa. For example, Norman and colleagues found that high
cholesterol levels (
≥
3.8 mmol/l) accounted for 59% of ischaemic
heart disease and 29% of ischaemic stroke burden in adults aged
30 years and over.
66
The prevalence of dyslipidaemia, especially
cholesterol has been shown to vary across regions in Africa.
In a study of healthy workers in Nigeria, 5% of the study
population had hypercholesterolaemia, 23% elevated total serum
cholesterol levels, 51% elevated low-density lipoprotein (LDL)
cholesterol levels and 60% low high-density lipoprotein (HDL)
cholesterol levels, with females recording better overall lipid
profiles.
66
Population-based studies in Tanzania and Gambia also
showed elevated total serum cholesterol levels of
>
5.2 mmol/l
in up to 25% of people aged
>
35 years. Elevated cholesterol
levels appear to be more prevalent in urban areas and among the
higher socio-economic classes.
66
Other factors
The epidemic of stroke, hypertension, diabetes and dyslipidaemia
in Africa is driven by multiple factors working collectively.
Obesity and lifestyle factors such as poor diet, sedentary lifestyle
and smoking contribute to the increasing rates of stroke in
Africa.
In a meta-analysis among West African populations, the
prevalence of obesity was 10.0%. A study in Benin found that
abdominal obesity was positively associated with increased
probabilityof themetabolicsyndrome.Obesitywasapredominant
risk factor for women compared to men, but smoking was
mostly a risk factor for men.
66
Additionally, structural and
system-level issues such as lack of infrastructure for healthcare,
urbanisation, poverty and lack of government programmes also
drive this epidemic and hamper proper prevention, surveillance
and treatment efforts.
66
Carotid atherosclerosis measured by increased carotid
intima–media thickness (CIMT) and carotid diameter have
been associated with stroke among Africans.
54,71-73
Furthermore
white matter hyperintensities may be a risk factor for stroke in
Africans.
74
Elevated homocysteine levels (associated with cardiovascular
endothelial injury)
75,76
and the metabolic syndrome (implying
concomitant hypertension, obesity, dyslipidaemia, and/or
hyperglycaemia)
77
have also been documented as risk factors for
stroke in Africans.
Unique aspects of stroke survivors in Africa
In Nigerian Africans, stroke impairs all facets of health-related
quality of life (HRQOL), particularly domains in the physical
sphere (physical, cognitive, psycho-emotional and eco-social
domains). The severity of impairment correlates with stroke
severity.
78-80
Many of these disabling strokes occur in young
people. Stroke occurs at a younger mean age of 57 years in
Africa compared to 66.0 years in high-income countries (HICs);
in those
≤
45 years: 24% in Africa, 8% in HICs).
53,56
Overall, stroke tended to occur in a younger population in
Africans compared to high-income countries.
53,56
This may be
due to genetic factors, a high proportion of undiagnosed and
uncontrolled hypertension, the shorter life expectancy in African
countries and a higher proportion of younger people.
53,81
Stroke is a leading cause of late-onset seizure disorder among
Africans.
82
It accounts for 22.5% of seizures after the age of 25
years.
82
In a Nigerian study, the most common seizure type was
simple partial, while the most common electro-encephalographic
finding was the presence of focal epileptiform discharges,
followed by focal slowing.
82
At the three-month follow up, 52%
of the patients had good seizure control.
82
In other studies, 48.3%
of Nigerian stroke patients had vascular cognitive impairment,
83
while major depression was found among 30% of African stroke
patients.
84
Despite these deleterious consequences of stroke, there
is poor community awareness of its risk factors and warning
signs in Ghana,
84,85
and poor awareness of its risk factors and
features among hospital workers in Nigeria.
83
Cost of care
The economic burden of stroke is considerable. The cost of
stroke for the year 2002 was estimated to be as high as $49.4