The SA Journal Diabetes & Vascular Disease Vol 16 No 1 (July 2019)

SA JOURNAL OF DIABETES & VASCULAR DISEASE

RESEARCH ARTICLE

VOLUME 16 NUMBER 1 • JULY 2019

(compared to women) is contrary to the literature

26,27

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 underrepresented 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 targeted for intensive BP control, LVH

screening and management interventions that promote left

ventricular remodelling.

Limitations and strengths

Several limitations must be borne in mind in this study. Firstly, this

was a cross-sectional study and the associations found are not causal

in nature. Secondly, there was the potential for social desirability