CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 2, March 2012
78
AFRICA
The relationship between cortisol, C-reactive protein
and hypertension in African and Causcasian women:
the POWIRS study
CLAIRE M TOLMAY, LEONE MALAN, JOHANNES M VAN ROOYEN
Research on the roles that C-reactive protein (CRP) and
other risk factors such as cortisol and obesity play in the
diagnosis of cardiovascular disease (CVD) in African and
Caucasian women has become increasingly imperative when
one considers the prevalence of hypertension in these groups.
CRP and cortisol have been associated with an increased
prevalence of hypertension and obesity. Cortisol has also
been linked with both hypertension and the hypothalamic–
pituitary–adrenal (HPA) response. African women have
previously presented with an increased vascular reactivity.
Conversely, Caucasian women have displayed an increased
central cardiac reactivity. We included African (
n
=
102) and
Caucasian (
n
=
115) women in the study, matched for age
and body mass index. Elevated CRP levels were observed in
African women compared to Caucasian women. A trend of
hypocortisolism was exhibited in both hypertensive ethnic
groups. Systolic blood pressure (SBP) and a vascular marker,
arterial compliance (Cw), predicted hypertension in African
women. Conversely, in Caucasian women, only SBP predicted
hypertension. These results suggest the apparently diverse
roles that dysregulation by the HPA axis, in conjunction
with the respective cardiac and vascular responses in both
Caucasian and African women, can play in future cardiovas-
cular risk for these groups.
Keywords:
cortisol, C-reactive protein, hypertension, ethnic
Submitted 5/10/10, accepted 14/6/11
Cardiovasc J Afr
2012;
23
: 78–84
DOI: 10.5830/CVJA-2011-035
Several studies in southern Africa have explored the relationship
between C-reactive protein (CRP), cortisol and the prevalence of
hypertension, and cardiovascular, anthropometric and other risk
factors in the development of cardiovascular disease (CVD).
1-7
These factors include the influence of urbanisation in different
ethnic groups.
2-7
Urbanisation has been shown to play a signifi-
cant role in increasing cardiovascular reactivity in Africans when
compared to other ethnic groups.
2,3,5
These studies have also
demonstrated a correspondingly higher prevalence of hyperten-
sion in this group compared to Caucasians, Indians and those of
mixed origin.
2,3,5
African women have previously been shown to have signifi-
cantly higher high-sensitivity C-reactive protein (hs-CRP) and
blood pressure (BP) levels compared to their Caucasian coun-
terparts. However, no cardiovascular parameters could explain
the variation in levels of this inflammatory marker.
6
Caucasian
women, however, did show strong significant correlations
between CRP, Windkessel compliance (Cw) and total peripheral
resistance (TPR).
6
Nevertheless these correlations became non-
significant and weak after adjustments were made for age, body
mass index (BMI) and waist circumference (WC).
6
Recently, Hamer and Malan
6
have revealed that urbanAfricans
had higher BP and hypertension (HT) rates in conjunction with
higher arterial resistance and lower cardiac output compared to
their rural counterparts. The exact mechanism of the increased
prevalence of hypertension in this ethnic group is still unknown
but great strides have been made in the determination of other
possible risk factors such as psychosocial stress and coping
responses.
1,6,7
Hypocortisolism, in conjunction with urbanisa-
tion, has been proposed as a possible contributing factor to the
increased incidence of hypertension in African women,
4
however
further studies need be conducted in order to assess what role
this observation plays in association with other risk factors for
CVD in this ethnic group.
Several studies have shown that acute or chronic stress may
lead to dysregulation of the hypothalamic–pituitary–adrenal
(HPA) axis, which in turn is mediated by certain inflamma-
tory markers such as CRP and other stress hormones, including
cortisol.
8-11
Free fatty acids, which are released from increased
visceral or abdominal adipose tissue, also play a role in heighten-
ing levels of CRP.
11-14
Elevated levels of cortisol are also linked
to increased adiposity and subsequently increased inflammation,
which consequently leads to increased risk for cardiovascu-
lar disease.
10,11
Moreover, this link is further supported by the
decrease in inflammatory mediators in individuals where weight
loss was demonstrated.
15
It is important to note, however, that although several of these
studies have explored in detail the relationships between cortisol,
CRP and vascular responses, and the prevalence of hyperten-
sion, and that although guidelines have been set for other ethnic
groups,
15
the investigation of African and Caucasian women from
South Africa has been limited. It is therefore imperative that the
relationship between cortisol, CRP and vascular responses, and
the prevalence of hypertension be explored further in the ethnic
groups of South Africa in order to fully substantiate and assess
possible risk for CVD.
Methods
The POWIRS (Profiles of Obese Women with Insulin Resistance
Syndrome) study comprised two cross-sectional studies, of
which the first was performed on 102 urban African women.
This study was then repeated on a group of 115 Caucasian
women. The two groups were matched on the basis of age and
BMI. Attempts were made to choose African women of a higher
Hypertension in Africa Research Team (HART), North-West
University, Potchefstroom, South Africa
CLAIRE M TOLMAY, MSc
LEONE MALAN, RN, PhD,
JOHANNES M VAN ROOYEN, DSc
