CARDIOVASCULAR JOURNAL OF AFRICA • Vol 22, No 5, September/October 2011
AFRICA
261
Global cardiovascular risk profiles of untreated
hypertensives in an urban, developing community
in Africa
MJ MASEKO, GR NORTON, OH MAJANE, N MOLEBATSI, AJ WOODIWISS
Summary
Introduction:
Blood pressure (BP) control in people of
African descent is poor, largely because of a lack of treat-
ment. Although the requirements for immediate initiation
of antihypertensive drug therapy are defined by global
cardiovascular risk, the global cardiovascular risk profiles of
untreated hypertensives at a community level are uncertain.
Aim:
To identify the distribution of global cardiovascular risk
profiles of untreated hypertensives in an urban, developing
community of African descent in South Africa.
Methods:
As part of the African Programme on Genes in
Hypertension, we assessed nurse-derived clinic BP (the mean
of five standardised BP values obtained according to guide-
lines), current antihypertensive therapy, and total cardiovas-
cular risk in 1 029 participants older than 16 years of age
from randomly selected nuclear families from the SouthWest
Township of Gauteng (SOWETO).
Results:
Approximately 46% of participants had systolic/
diastolic BP values
≥
140/90 mmHg and ~23% of partici-
pants were hypertensives not receiving antihypertensive
medication. Approximately 12% of untreated hypertensives
had a high added risk and ~18% a very high added risk
(6.7% of the total sample). In untreated hypertensives, in
contrast to the absence of severe hypertension and diabetes
mellitus in those with lower risk profiles, a high cardiovas-
cular risk profile in this group was characterised by severe
hypertension in ~52% and diabetes mellitus in ~33%. Based
on a high added risk carrying at least a 20% chance and a
very high added risk at least a 30% chance of a cardiovas-
cular event in 10 years, this translates into 1 740 events per
100 000 of the population within 10 years, events that could
be prevented through antihypertensive drug therapy.
Conclusions:
In an urban, developing community of African
ancestry, a significant proportion (6.7%) of people may
have untreated hypertension and a global cardiovascular
risk profile that suggests a need for antihypertensive drug
therapy. Cardiovascular risk in this group is driven largely
by the presence of severe hypertension or diabetes mellitus.
Keywords:
blood pressure control, antihypertensive treatment,
detection of hypertension.
Submitted 9/4/10, accepted 26/11/10
Published online 15/12/10
Cardiovasc J Afr
2011;
22
: 261–267
DOI: 10.5830/CVJA-2010-094
In economically developed countries, there is a continuous rela-
tionship between blood pressure (BP) and the risk of mortality
from ischaemic heart disease and stroke,
1
and hypertension is the
second most common risk factor for end-stage renal disease.
2
In
these countries, the risk for cardiovascular disease exists in both
elderly and young (18–39 years old) hypertensives.
3
In economically emerging countries, hypertension has mate-
rialised as the most prevalent risk factor for heart failure,
4
coro-
nary artery disease,
5
and stroke.
6,7
In contrast to the approximate-
ly 34–35% of all hypertensives and 55% of treated hypertensives
that are controlled to target BP levels in economically developed
countries,
8–11
by comparison, in economically emerging coun-
tries such as South Africa, only 14% of all hypertensives
12
and
33–44% of treated hypertensives in primary-care settings
13,14
are controlled to target BP. The major barrier to BP control in
economically emerging countries is lack of treatment.
12
Although a lack of treatment accounts for inappropriate BP
control in economically emerging communities,
12
the decision to
treat hypertension with drug therapy should be based on global
cardiovascular risk scores, rather than on the presence of hyper-
tension
per se
.
15
In this regard, it is acknowledged
16
that there is
little evidence to support the use of drug therapy in people who
have BP values between 140 and 159/90 and 99 mmHg and a
‘low or moderate added’ risk. Indeed, the most recent evidence
suggesting the use of drug therapy in this category is derived
from a study where 89% of patients were already receiving anti-
hypertensive therapy at baseline.
17
As BP control in the context of global cardiovascular risk in
untreated hypertensives in emerging communities in Africa has
to our knowledge never been described, in the present study we
aimed to determine the cardiovascular risk profiles of untreated
hypertensives in an urban, developing community of African
descent.
Methods
The present ongoing cohort study, which has been described
in recent publications,
18–25
was initiated in 2002 and conducted
according to the principles outlined in the Helsinki declara-
tion. The Committee for Research on Human Subjects of the
University of the Witwatersrand approved the protocol (approval
number: M02-04-72 and renewed as M07-04-69). Participants
gave informed, written consent. Nuclear families of black
African descent (Nguni and Sotho chiefdoms) with siblings
older than 16 years were randomly recruited from the South West
Cardiovascular Pathophysiology and Genomics Research
Unit, School of Physiology, Faculty of Health Sciences,
University of the Witwatersrand, Johannesburg, South Africa
MUZI J MASEKO, MS
GAVIN R NORTON, MB BCh, PhD
OLEBOGENG HI MAJANE, PhD
NOMONDE MOLEBATSI, RN
ANGELA J WOODIWISS, PhD,
