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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 27, No 6, November/December 2016
364
AFRICA
increased with reduced eGFR and advancing age, respectively;
third, the MetS emerged as the main risk factor for uncontrolled
hypertension.
In this study, 77.5%of patients had uncontrolled hypertension.
This observation agrees with previous reports highlighting the
fact that in most countries, less than 30% of patients achieve BP
goals,
20
and therapy with a single antihypertensive agent fails to
achieve BP goals in up to 75% of patients.
21
The frequency of uncontrolled hypertension observed in
the present study was somewhat higher than that reported in
primary care settings by Rayner
et al
. (60.2%)
22
and Dennison
et
al
. (64% in the public sector and 49% in the private sector)
23
in
South Africa and by Onwemu
et al
. (29.4%)
24
in Nigeria. It was
also higher than that observed at tertiary care level by Yaméogo
et al
. (54.2%)
25
in Burkina Faso, by Kramoh
et al
. (56.3%) in
Ivory Coast,
26
and by Ayodele
et al
. (68.6%)
27
and Sani
et al
.
(67%)
28
in Nigeria.
Our clinically generated frequency of uncontrolled
hypertension was quite similar to the 76.4% reported by Dzudie
et al.
29
in Cameroon but lower than the 97, 94 and 86.4%
previously reported by M’Buyamba-Kabangu
et al
., Sumaili
et
al
. and Katchunga
et al
. in the general population of Kinshasa
and south-eastern part of Democratic Republic of Congo,
respectively.
4-6
Higher frequencies of uncontrolled hypertension
ranging from 82.2 to 97.4% were also reported by Hendricks
et al
. from Namibia to Kenya in a community-based cross-
sectional study.
30
Apart fromdifferences inmethodology applied and population
characteristics studied, the higher frequency of uncontrolled
hypertension in sub-Saharan Africa appears to be multifactorial
and is determined by patients, care providers and healthcare
systems.
31
Among the factors related to patients, non-compliance
with diet and antihypertensive therapy has been reported to be
an important determinant of uncontrolled BP.
32
Non-compliance with antihypertensive therapy emerged in
our study as the second risk factor associated with uncontrolled
hypertension but the difference was not statistically significant.
In many studies, non-compliance with antihypertensive
therapy was responsible for two-thirds of the cases of
uncontrolled hypertension.
33,34
Krousel-Woods
et al
.
33
found that
non-compliance was associated with a nearly two-fold greater
risk (OR 1.68; 95% CI 1.01–2.88) of uncontrolled BP. Yaméogo
et al
.
25
in Burkina Faso found that non-compliance with both
diet and antihypertensive therapy was associated with an eight-
fold (OR 8.40; 95% CI 1.11–4.17;
p
=
0.04) and nearly three-fold
greater risk of uncontrolled hypertension, respectively.
With regard to the care provider, clinical therapeutic inertia
has been reported to be a major contributor to uncontrolled
hypertension.
35
Although patients with a high to very high CV
risk level need more than two antihypertensive drugs to reach
the BP goal,
8
the majority of patients in our study were still
on monotherapy, indicating clinical therapeutic inertia. The
association of high to very high residual global CV risk has
been reported by Yaméogo
et al
.
25
in Burkina Faso and Kramoh
et al
.
26
in Ivory Coast, using the Framingham CV risk score
and 2007 ESH/ESC guidelines, respectively. In addition, Bohen
et al
.,
35
using a cohort of hypertensive diabetics, found that
non-intensification of therapy is frequent in this category of
patients and is responsible for uncontrolled BP and glycaemia.
Uncontrolled SBP is more frequent and its frequency
increases with advancing age, especially after 60 years. A
Table 3. Biological characteristics of the study population as a whole and
by blood pressure control status
Variable
n
Whole group
(
n
=
298)
Controlled
HT
(
n
=
67)
Uncontrolled
HT
(
n
=
231)
p
-value
Blood glucose, mg/dl
237 115
±
53
104
±
27
119
±
59 0.011
(mmol/l)
6.38
±
2.94 5.77
±
1.50 6.60
±
3.27
Lipids
259
TC, mg/dl
220
±
58
225
±
60
219
±
57 0.548
(mmol/l)
5.7
±
1.5 5.83
±
1.55 5.67
±
1.48 0.462
LDL-C, mg/dl
135
±
55
139
±
57
134
±
55 0.537
(mmol/l)
3.50
±
1.42 3.60
±
1.48 3.47
±
1.42
HDL-C, mg/dl
63
±
18
62
±
19
63
±
18
0.530
(mmol/l)
1.63
±
0.47 1.61
±
0.49 1.63
±
0.47
TG, mg/dl
111
±
51
118
±
62
109
±
47 0.261
(mmol/l)
1.25
±
0.58 1.33
±
0.70 1.23
±
0.53
Creatinine, mg/dl
255 1.04
±
0.56 0.95
±
0.27 1.07
±
0.62 0.133
(μmol/l)
91.94
±
9.50 83.98
±
23.87 94.59
±
54.81
eGFR, ml/min/0.73 m² 255 82
±
31
86
±
28
81
±
32
0.319
Uric acid, mg/dl
259 6.38
±
2.50 6.60
±
2.40 6.30
±
2.50 0.488
Data are expressed as mean
±
standard deviation (SD) or relative frequency (%).
TC, total cholesterol ; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-
density lipoprotein cholesterol; TG, triglycerides; eGFR, estimated glomerular
filtration rate.
Table 4. Cardiovascular risk factors among the study population as a
whole and by blood pressure control status
Variable
n
Whole
group
(
n
=
298)
Controlled
HT
(
n
=
67)
Uncon-
trolled
HT
(
n
=
231)
p
-value
Age, %
298 86
87
86
0.989
Smoking, %
298
3
2
3
0.348
Alcohol, %
298 17
18
17
0.462
Overweight, %
298 35
31
36
0.228
Obesity, %
298 17
16
22
0.228
Central obesity, %
298 66
66
66
1.000
Diabetes, %
298 37
22
42
0.003
Hypercholesterolaemia, % 259 17
61
51
0.229
Low HDL-C, %
259 16
13
24
0.034
Hypertriglyceridaemia, % 259 18
18
15
0.700
Hyperuricaemia, %
259 33
36
26
0.210
Dipstick proteinuria, % 227 16
18
12
0.396
Renal failure, %
255 30
12
21
0.103
ECG-LVH, %
164 21
16
14
0.843
MetS, %
298 10
8
15
0.105
Global CV risk, %
298
Low
31
69
19
0.0001
Moderate
39
18
45
0.0006
High/very high
30
13
38
0.03
Data are expressed as mean
±
standard deviation (SD) or relative frequency (%).
HDL-C, high-density lipoprotein cholesterol; ECG-LVH, electrocardiographi-
cally determined left ventricular hypertrophy; MetS, metabolic syndrome; CV,
cardiovascular risk.
Table 5. Multivariate independent determinants associated with
uncontrolled hypertension
Variable
B SE OR (95% CI)
p
-value
Constant
–1.901 0.924
–
–
MetS
+
vs MetS–
0.877 0.444 2.40 (1.008–5.735)
0.04
Non-compliance vs compliance
B, regression coefficient; SE, standard error; OR, odds ratio; MetS, metabolic
syndrome.