Moekanyi Jeffrey Sibiya
A dissertation submitted to the Faculty of Health Sciences, University ofthe Witwatersrand,
for the degree of Master of Science in Medicine.
Johannesburg,2012Cholesterol is an important determinant of atherogenesis. However, populations of African
ancestry have low total and LDL cholesterol concentrations (anti-atherogenic), but elevated
triglyceride concentrations and low HDL concentrations (pro-atherogenic). The role of
circulating lipids in atheroma formation in groups of African descent is uncertain. Therefore,
in the current study I evaluated whether circulating lipids are independently associated with
carotid intima media thickness (C-IMT), a surrogate marker of atheroma, in an urban
developing community of African ancestry in SOWETO South Africa. 430 participants were
randomly selected. C-IMT was determined from Doppler images of the carotid artery using a
SonoSite (SonoCalc ™ IMT) version 3.4 device. In bivariate analysis total cholesterol,
total:HDL cholesterol ratio, LDL cholesterol and triglyceride concentrations were all
associated witp C-IMT (r=0.24 to r=0.26, p-values <0.0001) as were all indices of obesity (r=
0.16 to 0.30, p<0.001). However, in multivariate models which included adjustments for age,
clinic systolic blood pressure, diabetes mellitus, smoking, treatment for hypertension, regular
alcohol intake, heart rate and postmenopausal status (in women) neither the lipid variables
nor the indices of obesity remained associated with C-IMT (total cholesterol r=-0.01,
p=0.884; LDL r=0.02, p=0.682; TRGL r=-0.01, p=0.832; HDL r=-0.04, p=0.371; total:HDL
cholesterol ratio r=0.02, p=684). In multivariate regression analysis only age (p<0.0001) and
gender (p< 0.05) were independently associated with C-IMT.
In conclusion, the current study shows that in an urban developing community of African
ancestry with low cholesterol concentrations and a high prevalence of obesity there is no
independent relationship between either circulating lipid concentrations and C-IMT or
measures of obesity and C-IMT. However, age and gender independently predicted C-IMT in
this population
