CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 7, August 2012
AFRICA
381
to TOD is shown in Table 3. Subjects with TOD had significantly
higher (
p
<
0.001) mean SBP (167.1
±
15.6 mmHg) than those
without TOD (156.3
±
18.7 mmHg). Mean DBP was also
significantly higher (
p
<
0.001) in those with TOD (102.3
±
9.5
mmHg) than those without (95.8
±
13.5 mmHg).
The prevalence of LVH was 27.9% and atrial fibrillation was
16.4%. Subjects with LVH had significantly higher (
p
<
0.001)
SBP (161.7
±
18.9 mmHg) compared to those without LVH
(153.3
±
16.2 mmHg) and their DBP was also significantly
higher (
p
<
0.001) at 99.4
±
9.5 mmHg, compared with 91.5
±
10.1 mmHg.
Grade 3 hypertensive retinopathy was present in 2.2% of the
study population, and the commonest retinopathy was grade 1
(40.2%), followed by grade 2 (37.6%). Microalbuminuria was
present in 12.3% and gross proteinuria in 15.2%. The established
CVD found in the subjects is shown in Table 4. History of
stroke was found in 6.3% and CHF in 4.6% of the participants.
Ischaemic changes and evidence of old myocardial infarcts were
seen on ECG in 12.3% of the participants. However, only 0.5%
gave a history of myocardial infarction and 1.2% gave a history
of angina. Peripheral vascular disease was found in 3.6% of the
subjects, of whom 73.3% (11/15) were diabetic. Overall, 45
(10.8%) subjects had established CVD.
The results of multiple regression analyses after adjusting
for potentially confounding variables are presented in Table 5,
showing the association between TOD and selected variables.
The odds of developing TOD were increased by new diagnosis
of hypertension, systolic blood pressure
≥
180 mmHg/diastolic
blood pressure
≥
110 mmHg, and diabetes mellitus.
Discussion
The main findings of this study were the following: (1) The
presence of TOD was frequent in this rural adult population; (2)
The peak age for incidence of TOD was around 47 to 50 years,
that is middle age; (3) TOD was related to the presence of newly
diagnosed hypertension, stage 3 SBP and DBP, and diabetes
mellitus; (4) The presence of established CVD was relatively
frequent in this population; (5) There was a low detection rate,
treatment and control of hypertension; (6) Atrial fibrillation was
found in 16.4% of the population and this may have increased
the risk of stroke as no patients were on treatment; (7) In spite
of the low levels of angina and myocardial infarction, ischaemic
changes and evidence of old infarcts were found in the ECGs of
12.3% of the population studied.
The present study contributes to our knowledge on TOD
in Nigerian hypertensives in several ways. First, our study
demonstrates an incidence rate of TOD of 43.1% and established
Table 1. Characteristics of the
subjects included in the study
Males
(
n
=
184)
Mean (SD)
Females
(
n
=
231)
Mean (SD)
Total
(
n
=
415)
Mean (SD)
Age (years)
43.4 (
±
20.2) 50.4 (
±
13.2) 46.9 (
±
16.7)
BMI (kg/m
2
)
25.1 (
±
4.8) 28.7 (
±
6.5) 26.9 (
±
5.7)
Waist circumference (cm)
86.5 (
±
14.7) 92.6 (
±
13.3) 89.5 (
±
14.0)
SBP (mmHg)
159.4 (
±
25.5) 156.9 (
±
24.2) 158.2 (
±
24.9)
DBP (mmHg)
98.7 (
±
13.6) 94.9 (
±
17.5) 96.8 (
±
15.4)
Level of education
None
(28) 15.2% (59) 25.5% (87) 21.0%
Primary
(101) 54.9% (136) 58.9% (237) 57.1%
Secondary
(43) 23.4% (31) 13.4% (74) 17.8%
Tertiary
(12) 6.5% (5) 2.2% (17) 4.1%
Current cigarette smoker
(21) 11.4% (0) 0.0% (21) 5.1%
Current tobacco use*
(0) 0.0% (3) 1.3% (3) 0.7%
Diabetes
(13) 7.1% (27) 11.7% (40) 9.6%
Hypercholesterolaemia
Hypertension (
≥
140/90 mmHg) (19) 10.3% (22) 9.5% (41) 9.9%
Newly diagnosed
(163) 88.6% (193) 83.5% (356) 85.8%
Self-reported
(21) 11.4% (38) 16.5% (59) 14.2%
Receiving treatment in past
3 months
(4) 19.0% (7) 18.4% (11) 18.6%
BP control
(1) 25.0% (2) 28.6% (3) 27.3%
*Tobacco use (chewing/snuffing).
TABLE 2. PREVALENCE OF HYPERTENSIVE TARGET
ORGAN DAMAGEAMONG PARTICIPANTS
Target-organ damage
Number (
n
=
415)
Prevalence (%)
Heart LVH
116
27.9
LAE
91
21.9
Atrial fibrillation
68
16.4
Old infarcts/ischaemic changes
51
12.3
Retinopathy
grade 0
83
20.0
grade 1
167
40.2
grade 2
156
37.6
grade 3
9
2.2
grade 4
0
0.0
Renal damage*
Microalbuminuria
51
12.3
Gross proteinuria
63
15.2
LVH
=
left ventricular hypertrophy; LAE
=
left atrial enlargement;
*Men, microalbuminuria
=
albumin-creatinine ratio (ACR) 2.5–25 mg/g
and gross proteinuria is ACR
>
25 mg/g; women, microalbuminuria
=
ACR 3.0–30 mg/g and gross proteinuria is ACR
>
30 mg/g.
TABLE 3. BLOOD PRESSURE RANGES OF SUBJECTS IN
RELATION TOTARGET-ORGAN DAMAGE
Blood pressure (mmHg)
Target organ
SBP (
±
SD) DBP (
±
SD)
p
-value
ECG abnormalities’
Present
161.7
±
18.9 99.4
±
9.5
Absent
153.3
±
16.2 91.5
±
10.1
<
0.001
Retinopathy
Present
155.6
±
15.4 93.7
±
12.1
Absent
152.8
±
18.2 95.2
±
13.0
0.52
Renal damage
Present
163.5
±
17.6 101.6
±
9.5
Absent
150.0
±
16.2 90.9
±
9.5
0.001
TABLE 4. PREVALENCE OF ESTABLISHED
CARDIOVASCULAR DISEASEAMONG PARTICIPANTS
CV complications
Number (
n
=
415)
Prevalence (%)
Stroke
26
6.3
Myocardial infarction
2
0.5
Angina
5
1.2
Congestive heart failure
19
4.6
Peripheral vascular disease
15
3.6
