Cardiovascular Journal of Africa: Vol 24 No 9 (October/November 2013) - page 9

CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 9/10, October/November 2013 AFRICA 347
most severe grade) was 9.9% (95% CI: 9.2–10.6%) (Table 2).
Among the 6 064 respondents who were diagnosed as having any
hypertension, only 14.1% (854) knew previously that they were
hypertensive. Among the 2 975 respondents who were observed
to have grade 2 or 3 hypertension, 19.8% (588) were aware of
their hypertension status.
The prevalence of hypertension increased with age, ranging
from 32.1% in 40–49 year olds to 58.2% in those aged ≥ 80 years
(Table 3). The prevalence was higher in females (46.8%) and
in urban participants (51.6%). The prevalence was also higher
among illiterate respondents (47.2%). There was a wide variation
in prevalence according to GPZ, the lowest being in the south-
south GPZ (34.2%), and highest in the north-east GPZ (60.5%).
The prevalence of hypertension increased from the most
affluent (39.2%) to the least affluent (52.1%). The prevalence of
hypertension also increased with BMI category; 39.6% of those
who were underweight had hypertension compared with 59.8%
in those who were obese. The same trends were noted with
grades 2 and 3, and grade 3 hypertension.
With univariate analysis, age, female gender, living in an
urban area and being illiterate were strongly associated with all
grades of hypertension (p < 0.001) (Table 3). Using the south-
south GPZ as the baseline, associations with GPZ were more
variable. Socio-economic status was inversely associated with
hypertension (p < 0.001); the odds ratio of hypertension were
inversely associated with affluence. Compared with those with
a normal BMI, being overweight, obese or underweight were all
associated with hypertension.
Multivariate analysis was undertaken using the same set of
variables, excluding literacy due to its correlation with the measure
of SES (Table 4). In this analysis, older age, female gender, urban
area of residence and high and low BMI were independently
associated with hypertension at the p < 0.001 level, with the same
trends within categories as in the univariate analysis. Findings
with regard to GPZ showed that in relation to the south-south,
TABLE 3.ASSOCIATION BETWEEN HYPERTENSIONAND
SPECIFIC RISK FACTORS (UNIVARIATEANALYSIS)
Parameters
Any hypertension
SBP ≥ 140,
DBP ≥ 90 mmHg
Grade 2 and 3
hypertension
SBP ≥ 160,
DBP ≥ 100 mmHg
Grade 3 hypertension
SBP ≥ 180,
DBP ≥ 110 mmHg
OR 95% CI p-value OR 95% CI p-value OR 95% CI p-value
Age group (years)
40–49 1.00 1.00 1.00
50–59 1.88 1.71–2.07 < 0.001 2.08 1.84–2.34 < 0.001 1.99 1.67–2.38 < 0.001
60–69 2.51 2.27–2.77 < 0.001 2.70 2.39–3.06 < 0.001 2.55 2.13–3.06 < 0.001
70–79 2.82 2.47–3.22 < 0.001 3.08 2.65–3.59 < 0.001 3.05 2.50–3.72 < 0.001
≥ 80 2.95 2.49–3.49 < 0.001 3.33 2.79–3.98 < 0.001 3.29 2.60–4.18 < 0.001
Gender
Male 1.00 1.00 1.00
Female 1.19 1.10–1.27 < 0.001 1.37 1.26–1.49 < 0.001 1.33 1.18–1.50 < 0.001
Residence
Rural 1.00 1.00 1.00
Urban 1.42 1.21–1.66 < 0.001 1.46 1.23–1.73 < 0.001 1.48 1.20–1.82 < 0.001
Literacy
Literate 1.00 1.00 1.00
Illiterate 1.23 1.13–1.35 < 0.001 1.24 1.12–1.38 < 0.001 1.23 1.09–1.40 < 0.001
Geo-political zones
North-east 2.94 2.27–3.81 < 0.001 2.46 1.87–3.24 < 0.001 2.61 1.84–3.71 < 0.001
South-east 1.34 1.11–1.60 0.002 1.28 1.03–1.59 0.029 1.45 1.07–1.96 0.017
South-
south
1.00 1.00 1.00
North-
west
2.04 1.72–2.42 < 0.001 1.56 1.25–1.95 < 0.001 1.48 1.10–2.0 0.011
South-
west
1.29 1.07–1.55 0.006 1.20 0.96–1.51 0.108 1.33 0.99–1.78 0.056
North-
central
1.26 1.02–1.54 0.03 1.03 0.80–1.32 0.824 1.08 0.79–1.48 0.635
Socio-economic status
Affluent 1.00 1.00 1.00
Moderate-
ly affluent
1.19 1.08–1.32 < 0.001 1.14 1.02–1.28 0.025 1.15 0.98–1.35 0.084
Least
affluent
1.69 1.52–1.87 < 0.001 1.78 1.58–2.01 < 0.001 1.83 1.55–2.15 < 0.001
Body mass index (13 352)
Under-
weight
0.92 0.81–1.04 0.163 0.95 0.83-1.10 0.489 1.00 0.82-1.22 0.998
Normal 1.00 1.00 1.00
Over-
weight
1.45 1.32–1.6 < 0.001 1.45 1.30–1.62 < 0.001 1.45 1.27–1.66 < 0.001
Obese 2.08 1.78–2.43 < 0.001 2.15 1.85–2.50 < 0.001 2.08 1.73–2.50 < 0.001
TABLE 4.ASSOCIATION BETWEEN HYPERTENSIONAND
SPECIFIC RISK FACTORS IN MULTIVARIATEANALYSIS*
Parameters
Any hypertension
SBP ≥ 140,
DBP ≥ 90 mmHg
Grade 2 and 3
hypertension
SBP ≥ 160,
DBP ≥ 100mmHg
Grade 3 hypertension
SBP ≥ 180,
DBP ≥ 110 mmHg
OR 95% CI p-value OR 95% CI p-value OR 95% CI p-value
Age groups (years)
40–49 1.00 1.00 0.001 1.00 < 0.001
50–59 2.07 1.88–2.29 < 0.001 2.24 1.99–2.54 < 0.001 2.08 1.73–2.49 < 0.001
60–69 3.24 2.93–3.58 < 0.001 3.39 2.99–3.84 < 0.001 2.99 2.48–3.61 < 0.001
70–79 3.91 3.41–4.49 < 0.001 4.10 3.51–4.80 < 0.001 3.80 3.06–4.72 < 0.001
≥ 80 4.24 3.51–5.13 < 0.001 4.63 3.79–5.65 4.20 3.24–5.44
Gender
Male 1.00 1.00 1.00
Female 1.26 1.16–1.37 < 0.001 1.44 1.31–1.58 < 0.001 1.36 1.18–1.56 < 0.001
Residence
Rural 1.00 1.00 1.00
Urban 1.31 1.14–1.49 < 0.001 1.32 1.12–1.54 < 0.001 1.33 1.10–1.6 < 0.003
Geo-political zones
North-east 3.81 2.94–4.92 < 0.001 3.14 2.40–4.1 < 0.001 3.16 2.24–4.45 < 0.001
South-east 1.27 1.06–1.53 0.012 1.21 0.97–1.5 0.094 1.35 1.00–1.82 0.053
South-
south
1.00 1.00 1.00
North-
west
2.53 2.14–2.98 < 0.001 1.89 1.52–2.36 0.001 1.74 1.29–2.34 < 0.001
South-
west
1.16 0.98–1.38 0.090 1.07 0.86–1.33 0.536 1.20 0.90–1.59 0.208
North-
central
1.29 1.05–1.58 0.016 1.04 0.81–1.03 0.766 1.07 0.79–1.46 0.644
Socio-economic status
Affluent 1.00 1.00 1.00
Moderate-
ly affluent
0.97 0.88–1.06 0.473 0.91 0.81–1.03 0.130 0.94 0.80–1.11 0.467
Least
affluent
1.09 0.97–1.22 0.128 1.14 1.00–1.29 0.056 1.17 0.99–1.39 0.063
Body mass index (13 352)
Under-
weight
0.68 0.60–0.77 < 0.001 0.69 0.60–0.8 < 0.001 0.74 0.61–0.9 0.003
Normal 1.00 1.00 1.00
Over-
weight
1.69 1.53–1.86 < 0.001 1.63 1.46–1.82 < 0.001 1.59 1.39–1.82 < 0.001
Obese 2.61 2.23–3.05 < 0.001 2.53 2.16–2.97 < 0.001 2.35 1.92–2.87 < 0.001
*Literacy was excluded from the multivariate model as it was associated with socio-
economic status.