Cardiovascular Journal of Africa: Vol 29 No 6 (November/December 2018)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 6, November/December 2018

AFRICA

349

and may point to a potential measurement bias in that household

chores were classified as moderate-intensity physical activity. It

is well established that women engage in household chores more

than men.

Participants of lower socio-economic status were more likely

to be physically inactive because of poor knowledge of the

health benefits of physical exercise and/or the unavailability

of social environment and amenities for engaging in physical

exercise.

Population-based interventions need to address these

gaps through health education, campaigns and provision of

public facilities for exercise.

Cigarette smoking increases the risk of hypertension

two-fold,

and environmental exposure to cigarette smoke

increases the risk of adverse effects by at least 10%.

Although

the smoking prevalence of 11.9% reported in this study is

lower than the South African national figure (16.2%), it closely

aligns with the racial, gender and age trends described in

previous national surveys.

26,27

This result reflects the gains of

the tobacco-control programme in South Africa. However, the

16.3% of participants who were non-smokers but exposed to

environmental tobacco smoke raises serious cause for concern

and indicates that screening for tobacco use should include

enquiry about exposure to second-hand smoke, and if present,

prompt discussions on how the patient can be protected,

including exploring the enforcement of anti-smoking legislation.

The prevalence of snuff use found in this study was

significantly higher than the South African national average

(19.5 vs 6.7%),

and has implications in that a previous study

among South African women reported higher but statistically

insignificantly increased BPs among snuff users compared to

non-users.

Such BP increases in a setting of high snuff use and

multiple co-existing CV risks (as in this study), may translate into

substantial risk of CVD at the population level. It is therefore

imperative to promote cessation of snuff use among patients

with hypertension, until results of well-designed longitudinal

studies clarify the nature of this relationship.

Previous studies have shown that sociodemographic variables

such as education, religious beliefs and socio-economic status

influence smoking behaviours.

26,43,44

High smoking prevalence

among the whites in this study can, firstly, be explained by

income differentials, in that whites are less responsive to price

and tax hikes implemented in the South African tobacco-control

programme and continue to smoke at high rates. Secondly, the

coloured (mixed ancestry) population, who are known to smoke

more than other racial groups at a national level, were under-

represented in the population groups in the current study setting.

Studies have shown varying relationships between alcohol

use and the odds of being hypertensive. While a higher mean

number of standard drinks consumed

increases the odds, a

reduction in alcohol consumption is associated with a reduction

in blood pressure in a dose-dependent manner in both healthy

and hypertensive participants, with an apparent threshold effect

at two drinks per day.

The findings on alcohol use in this study

(Tables 2, 6) are consistent with prevalence and sociodemographic

trends described in recent nationally representative studies in

South Africa; the highest prevalence occurring among whites

(male or female) living in urban areas, who have more than

secondary education and the highest wealth quintile.

26,27,46

The findings that participants aged 20 to 39 years had a

higher prevalence of alcohol use and were more likely to be

physically inactive have been reported in a previous South

African article.

Considering that these are young people, the

cumulative effects of unattended co-existing CV risks over many

years may place this cohort at substantially elevated risk of

premature CVD-related morbidity and mortality later in life.

This is more so since a dose–response relationship (strongest

among black men) has been reported between alcohol use and

coronary calcification.

Young patients with hypertension who

have risky alcohol consumption behaviours should therefore be

prioritised for intensified CV risk assessment and management.

The prevalence of type 2 diabetes found in this study (30.2%)

was high and mirrors findings from other studies among

patients with co-existing CV risks: physical inactivity (78.8%),

obesity (66.7%), dyslipidaemia (41.4%), alcohol use (21.2%) and

smoking (11.1%).

25,48-51

This clustering of CV risks in patients

with diabetes underscores the necessity for more intensified

screening and management of CV risks in this group.

Although previous studies have suggested increased risk of

diabetes among women,

this study finds to the contrary. Being

male was the only correlate of diabetes. This may reflect variations

in the prevalence of CV risk across different populations.

However, these findings may have clinical implications, especially

that men in this study were also more likely to have other CV

risks (Table 4).

Hypercholesterolaemia is a major risk factor for CVD

and

was found in 26.5% of study participants. However, the true

prevalence of hypercholesterolaemia could have been higher

since 58.5% of participants either did not know their lipid profile

or had never been tested. This highlights a significant gap in

clinical practice in South African PHC and calls for strategies to

increase healthcare providers’ adherence to national guidelines

on hypertension.

Most CVDs have hereditary and environmental risk

components,

and a 14.9% prevalence of positive family history

of premature fatal CVD suggests a high burden of familial

predisposition to CVD in this population. Clinicians should

therefore routinely screen for family history of CVD, noting that

the odds of reporting a positive family history of fatal CVD is

four times higher among races other than black people.

Since

the pathological processes conferring increased risk of CVD

in those with a positive family history of CVD (particularly

macrovascular complications) start long before they become

clinically evident, primordial and primary prevention at PHC

level are crucial to deter or delay the onset of CVD.

In this study, most participants (60.7%) had their BP

controlled to target, more than in a previous study in the same

setting.

However, in the context of multiple risk factors, a

systolic BP below 140 mmHg may still confer significant risk of

CVD, since CV risk factors have differential effects on various

CVD outcomes, and a patient with moderate levels of multiple

risk factors could have a greater overall risk of CVD than a

patient with a high risk in only one factor.

While BP needs to be controlled to targets, CVD risk

assessment needs to be personalised, and individualised

interventions instituted during clinic visits. Poor BP control is

generally commoner among black patients with hypertension, as

is LVH.

53-55

It is therefore not surprising that most of the 5.2% of

participants who had LVH in this study were black. Given that

LVH is associated with a two- to four-fold increase in the risk of

premature CV morbidity and mortality,

black patients need to be