January 24, 2023Open Access
Carotid atherosclerosis in people of European, South Asian and African Caribbean ethnicity in the Southall and Brent revisited study (SABRE)
Key Result
African Caribbean ethnicity was associated with a significantly lower prevalence of carotid atherosclerotic plaques compared to European ethnicity (6% vs 16%, RR 0.48), while South Asians had a similar prevalence to Europeans.
Study Design
Type
Cross-Sectional (n=991)
Structured PICO
Does carotid atherosclerosis burden differ among European, South Asian, and African Caribbean ethnicities?
P
Population
991 individuals (437 European, 326 South Asian, 228 African Caribbean) from the Southall and Brent Revisited (SABRE) longitudinal study, aged 40-69 years at baseline, living in West and North London.
O
Outcome
Carotid artery plaques and intima-media thickness (cIMT)surrogate
Carotid plaque prevalence is significantly lower in African Caribbean individuals compared to European and South Asian individuals, independent of traditional ASCVD risk factors, casting doubt on the utility of carotid ultrasound for assessing risk across diverse ethnic groups.
Main Result
Effect estimate: RR 0.48 (95% CI 0.28-0.82)
Absolute Event Rate: 6% vs 16%
p-value: p=0.013
Limitations
- Cross-sectional design precludes causal conclusions
- Possible bias due to non-participation, attrition, missing data, and residual confounding
- Low frequency of carotid plaque, particularly in African Caribbeans, may have limited the ability to detect small differences
- Crude categorization of ethnicity may obscure important differences within ethnic groups
- Limited data available regarding exposures that occurred prior to migration or extent of acculturation
Abstract
Background: Atherosclerotic cardiovascular disease (ASCVD) risk differs by ethnicity. In comparison with Europeans (EA) South Asian (SA) people in UK experience higher risk of coronary heart disease (CHD) and stroke, while African Caribbean people have a lower risk of CHD but a higher risk of stroke. Aim: To compare carotid atherosclerosis in EA, SA, and AC participants in the Southall and Brent Revisited (SABRE) study and establish if any differences were explained by ASCVD risk factors. Methods: Cardiovascular risk factors were measured, and carotid ultrasound was performed in 985 individuals (438 EA, 325 SA, 228 AC). Carotid artery plaques and intima-media thickness (cIMT) were measured. Associations of carotid atherosclerosis with ethnicity were investigated using generalised linear models (GLMs), with and without adjustment for non-modifiable (age, sex) and modifiable risk factors (education, diabetes, hypertension, total cholesterol, HDL-C, alcohol consumption, current smoking). Results: < 0.001). In those with plaque, total plaque area, numbers of plaques, plaque class, or greyscale median did not differ by ethnicity; adjustment for risk factors had minimal effects. cIMT was higher in AC than the other ethnic groups after adjustment for age and sex, adjustment for risk factors attenuated this difference. Conclusion: Prevalence of carotid artery atherosclerotic plaques varies by ethnicity, independent of risk factors. Lower plaque prevalence in in AC is consistent with their lower risk of CHD but not their higher risk of stroke. Higher cIMT in AC may be explained by risk factors. The similarity of plaque burden in SA and EA despite established differences in ASCVD risk casts some doubt on the utility of carotid ultrasound as a means of assessing risk across these ethnic groups.