Cardiovascular Journal of Africa: Vol 27 No 6 (November/December 2016)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 27, No 6, November/December 2016

AFRICA

365

greater frequency of uncontrolled SBP has been reported by

Yaméogo

et al

. in Burkina Faso and Ayodele

et al.

in Nigeria.

25,27

Significant reduction in systemic arterial elasticity is common

with advancing age. This decrease in elasticity results in higher

systolic pressures, as large vessels become less able to reduce the

pressure generated by the left ventricle by means of distension.

On the other hand, while increases in peripheral resistance will

cause elevation in diastolic pressure, the loss of large vessel

elasticity does the opposite. Therefore, with increasing age, the

counteracting forces may keep the diastolic pressure normal,

while in the background, there is increasing systolic pressure.

20,25,26

In our study, the frequency of uncontrolled SBP and DBP

increased with reduced eGFR. Schmitt

et al

reported in a

study of 7 227 chronic kidney disease (CKD) patients receiving

at least one antihypertensive drug, that only 35% of them had

controlled blood pressure. They suggested non-compliance with

therapy as the main determinant of uncontrolled hypertension in

these CKD patients. Indeed, 33% of patients with CKD were not

compliant with therapy and the frequency of non-compliance

increased with decreased eGFR.

In univariate analysis, diabetes and low HDL-C levels

were significantly associated with uncontrolled hypertension,

whereas in multivariate analysis, the MetS and self-reported

non-compliance emerged as the main predictors of risk for

uncontrolled hypertension; however, the differences observed in

non-compliance did not reach the level of statistical significance.

Poor adherence to therapeutic plans and non-compliance

with antihypertensive therapy have been reported to be perhaps

the most important factors responsible for poor BP control.

In most cases, poverty has been adduced to be responsible for

non-compliance, especially in sub-Saharan Africa.

Health

education and patient counselling, along with availability of free

drugs could help improve adherence to antihypertensive drug

therapy.

Previous reports have associated the MetS with an increased

risk of uncontrolled hypertension.

38,39

Central obesity via secreted

adipocytokines, mainly adiponectin and leptin, appears to be

the link between the MetS and uncontrolled hypertension.

Adiponectin, besides its effects on insulin sensitivity, may act

directly on the vasculature; indeed, hypo-adiponectinaemia was

found to be associated with impaired endothelium-dependent

dilation in humans.

Furthermore, leptin has also been

reported to increase sympathetic tone and therefore the renin–

angiotensin system, with subsequent increase in vascular tone

and remodelling.

Several potential limitations of the study need to be

underscored. The cross-sectional design of the study did not

allow us to establish clear evidence of a causal relationship

between the variables of interest. The study sample size was not

large enough to be empowered to detect additional associations.

The frequency of uncontrolled hypertension could have been

overestimated by the lack of inclusion of home blood pressure

monitoring while defining BP control.

The non-quantitative

evaluation of compliance with antihypertensive therapy may

have caused underestimation of this important determinant of

BP control; the same could be true for socio-economic status and

compliance with diet, especially salt intake. The use of a clinically

based sample may limit generalisation of the conclusions of this

study to the entire hypertensive population because of bias in

referral of patients to the source of care.

Conclusion

Uncontrolled hypertension was frequent in the present case

series and was associated with factors related to lifestyle and diet,

which interact with blood pressure control.

The authors gratefully thank Dr Jeremie Muwonga for the facilities provided

for analysis of biological samples at the National Laboratory of the National

AIDS Control Program. We are indebted to Prof Dr Mashinda for his

pertinent advice and to all the staff of BDOM network, particularly Dr

François Minzemba and Dr Josée Nkoy Belila for their commitment during

the conduct of the study. We thank all the participants who, by their consent,

made the present study possible.

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