January 4, 2007
View Full PaperIncreased carotid intima‐media thickness in remote and urban Indigenous Australians: impact of diabetes and components of the metabolic syndrome
Key Result
Carotid intima-media thickness was significantly higher in remote and urban Indigenous Australians compared to Europeans, both in nondiabetic (0.73 vs 0.67 vs 0.64 mm) and diabetic groups (P<0.001).
Study Design
Type
Cross-Sectional (n=385)
Multicenter
Yes
Structured PICO
Does carotid intima-media thickness differ between remote Indigenous, urban Indigenous, and urban European Australians with and without diabetes?
P
Population
385 adults including 119 remote Indigenous Australians, 144 urban Indigenous Australians, and 122 urban European Australians with and without diabetes.
O
Outcome
Carotid intima-media thickness (CIMT) measured by high-resolution B-mode ultrasound imaging of the common carotid arterysurrogate
Indigenous Australians, particularly those in remote areas, have significantly higher CIMT than European Australians, driven by diabetes, metabolic syndrome components, and other unmeasured factors.
Main Result
p-value: p=<0.001
Limitations
- Unmeasured variables (genetic, psychosocial and socioeconomic) may contribute to higher CIMT in these populations
Abstract
OBJECTIVE: Indigenous Australians have rates of cardiovascular (CVD) mortality some seven to 10-fold higher than non-Indigenous Australians aged 25-64 years. We aimed to evaluate the impact of type 2 diabetes and components of the metabolic syndrome on carotid intima-media thickness (CIMT) as a marker of cardiovascular risk in Indigenous Australians living in remote and urban environments and in Australians of European ancestry. DESIGN, PATIENTS AND MEASUREMENTS: CIMT was measured by high-resolution B-mode ultrasound imaging of the common carotid artery in 119 remote Indigenous, 144 urban Indigenous and 122 urban European Australians with and without diabetes. RESULTS: In nondiabetic participants, CIMT was lowest in Europeans (mean (SD) 0.64 mm (0.10)), higher in urban Indigenous Australians (0.67 mm (0.12)) and highest in remote Indigenous Australians (0.73 mm (0.15), P < 0.001). CIMT was higher with diabetes with the same pattern observed between populations: 0.73 mm, 0.79 mm and 0.82 mm, respectively (P < 0.001). Traditional risk factors (age, male gender, blood pressure and HbA1c) explained 35-45% of the variance of CIMT within each population group. However, differences in CIMT between population groups were maintained after adjustment for these cardiovascular risks plus cholesterol and smoking (P < 0.001). Factor analysis revealed that variables of the metabolic syndrome, together with smoking and elevated C-reactive protein (CRP) and urinary albumin-creatinine ratio (ACR), are likely to explain the higher CIMT in Indigenous Australians (and the urban-remote gradient). Unmeasured variables (genetic, psychosocial and socioeconomic) may also contribute to higher CIMT in these populations. CONCLUSION: Glycaemic control and metabolic syndrome components contribute significantly to premature atherogenesis in Indigenous Australians and we recommend that therapy should be targeted accordingly.