CARDIOVASCULAR JOURNAL OF AFRICA • Vol 21, No 1, January/February 2010
AFRICA
27
hol consumption. These lead to a greater incidence of atheroscle-
rosis, hypertension, diabetes, hyperlipidaemia and obesity, which
are risk factors for CVD.
7
More than 80% of CVD and its risk
factors are preventable with cost-effective measures but there is a
dearth of population-based data on risk factors in Nigeria.
In Nigeria, hypertension is the most common non-commu-
nicable disease and it has emerged as the most important risk
factor for CVD, affecting 15 to 30% of the population.
8-10
The
prevalence of other CVD risk factors is not as clearly defined.
The attributable risk for hypertension tends to be greater in
developing economies because the low rates of detection and
treatment in such countries result in a proportionately higher
rate of complications. A large number of hypertensive patients
present for the first time with fatal and non-fatal cardiovascular
events such as heart failure, coronary artery disease (CAD)
11
and
stroke. These complications can be lethal with a poor prognosis
and reduced life expectancy,
12,13
resulting in loss of man-hours,
diminished work productivity, a social burden, and increased
health expenditure. All these have a devastating impact on the
family and national economy.
The absence of well-developed programmes for identification
and comprehensive CVD risk assessment and management of
high-risk individuals may be responsible for this.
14
The economic
impact on the patient and family is enormous as the cost of care
is borne out of pocket and it affects people usually at the peak of
their productive years.
A high prevalence of CAD risk factors such as hypercho-
lesterolaemia has been reported in newly diagnosed hyperten-
sives
15,16
and in Nigerians belonging to a high socioeconomic,
westernised class.
17
Most of these were hospital-based studies. In
this study we examined the prevalence of selected cardiometa-
bolic risk factors in a representative sample of an adult popula-
tion dwelling in rural Nigeria where information about CVD, the
disease burden and risk factors is sparse.
Methods
We conducted a cross sectional survey from December 2002 to
November 2005 in a representative sample of 2 000 adults, aged
18 to 64 years who were permanent residents of the Egbeda local
government area (ELGA), a rural community in south-western
Nigeria, with a population of 128 000. Agricultural produc-
tion and livestock breeding are the main economic activities
of ELGA residents, whose average annual income is less than
US $1 000. The study protocol was evaluated and approved by
the Ethics of Human Research Committee of the State Ministry
of Health. Individual consent was obtained verbally and where
possible by written consent.
A systematic random sample of dwellings was selected from
lists drawn up by field enumerators. Consecutive eligible adults
were selected as the respondents. A maximum of three respond-
ents were chosen per household. Community health extension
workers (CHEW) collected the data for the study after being
trained in basic interviewing techniques and standard methods
of obtaining physical measurements. Instruments were adopted
from the WHO STEPS survey, and adapted to the local settings.
During the home visits, the interviewers collected information
on each subject via structured patient questionnaires and physi-
cal assessment. Information obtained in step 1 included demo-
graphic profile (age, gender), socioeconomic profile (education-
al and income level), self-reported cardiac risk factors (smoking,
level of physical activity, salt intake, fruit and vegetable intake
and family history), pre-existing cardiovascular conditions and
complications (hypertension, diabetes mellitus, ischaemic heart
disease, stroke, kidney disease).
Cigarette smoking was defined as smoking at least one
cigarette per day for at least one year. Data were also collected
on other forms of tobacco use such as chewing and snuffing.
Physical activity was assessed using a questionnaire that asked
participants about their work-related activities. Physical activity
was considered to be engaging in sustained physical activity for
at least 30 minutes on five or more days per week, whether in
leisure time or integrated into their everyday life.
A clinic visit was subsequently set up for each respondent at
the nearest primary healthcare centre (PHC) to enable him/her
to have physical measurements taken, with further assessment of
any incident cardiometabolic risk factors. In step 2, we assessed
physical status such as anthropometrics, which was measured
by body mass index (BMI), (kg/m
2
) and waist circumference
(WC) (cm). Overweight was defined as a BMI
≥
25.0 kg/m
2
and
increased CV risk as waist circumference
≥
88 cm for women
and
≥
102 cm for men.
Blood pressure (BP) was measured by trained health work-
ers according to the guidelines of the International Society of
Hypertension (ISH)/World Health Organisation (WHO; 1999)
and the seventh Joint National Committee on hypertension
(JNC-7).
18-20
Measurements were taken using a standard mercu-
ry sphygmomanometer with appropriate-sized cuff. Three BP
measurements were taken using the subject’s right arm with him/
her in the sitting position after five minutes of rest, allowing
one minute between measurements. The mean of three measure-
ments was used as the final value. Participants with an elevated
BP measurement had their BP measured again after one to two
weeks; the average BP on the second visit was used as the crite-
rion for the diagnosis and control of hypertension. In addition,
all treated hypertensive patients had their BP measured after one
to two weeks.
Hypertension was defined as systolic blood pressure (SBP)
of
≥
140 mmHg, diastolic blood pressure (DBP) of
≥
90 mmHg,
or current treatment with antihypertensive drugs in subjects with
a history of hypertension. Awareness of hypertension meant
a previous diagnosis of hypertension or high blood pressure.
Controlled hypertension was defined as treated hypertension
with a SBP
<
140 mmHg and a DBP
<
90 mmHg at the second
BP measurement.
Venous blood samples were obtained via the antecubital vein
for biochemical assessment in step 3, including fasting serum
total cholesterol, high-density lipoprotein cholesterol (HDL-C),
low-density lipoprotein cholesterol (LDL-C), triglycerides and
fasting blood glucose levels. Diabetes was diagnosed either by a
history of previously known diabetes or a fasting plasma glucose
of
≥
126 mg/dl, and impaired fasting glucose was defined as fast-
ing plasma glucose of 100 to 125 mg/dl.
21
Hypercholesterolemia
was defined as a total cholesterol level
≥
200 mg/dl, HDL-C
<
40 mg/dl for men or
<
50 mg/dl for women, and/or triglyceride
concentration
≥
150 mg/dl. The metabolic syndrome was defined
according to Adult Treatment Panel (ATP) III criteria.
22
Statistical analysis
The data obtained were analysed using SPSS version 13.0
software (SPSS Inc., Chicago, Illinois, USA). Descriptive
