Determinants of carotid intima-medial thickness in an urban Australian Aboriginal population

Introduction We studied the determinants of carotid atherosclerosis in urban-dwelling Australian Aboriginals at high risk of atherosclerotic mortality and morbidity. Methods Cross-sectional study of self-selected adult Australian Aboriginals. Participants (n = 602) aged 18–74 years had risk factor assessment and carotid ultrasound to determine carotid intima-medial thickness (IMT) and the presence of plaque. The upper quartile (>0.71 mm in males and >0.62 mm in females) was used as a measure of increased carotid IMT. Results Over 80% of participants were overweight or obese; the prevalence of diabetes was 25%. Age was the major predictor of thick IMT, OR 3.0 (95% CI 2.0–4.5) per decade for males and OR 6.3 (3.3–12.0) for females. Waist circumference and blood glucose were independent predictors of IMT for men, with hypertension, pack-years of smoking, diabetes, and cholesterol ratio additional predictors for women. Plaque was highly prevalent (>40%) in this relatively young population and was predicted by increasing age, a history of smoking and total cholesterol/HDL ratio, but not sex. Conclusions Urban-dwelling Aboriginal Australians are at increased risk for early atherosclerosis. In this study an excess of obesity-related cardiovascular risk factors were the important contributors to increased IMT carotid atherosclerosis, but not inflammatory markers or other novel risk factors.