2.1 ETHNIC DIFFERENCES IN ASSOCIATIONS BETWEEN CAROTID IMT, CORONARY ARTERY CALCIFICATION AND CEREBROVASCULAR DISEASE. A POPULATION-BASED STUDY OF EUROPEANS, SOUTH ASIANS AND AFRICAN CARIBBEANS

Abstract

Aims. We compared associations between common carotid intima-media thickness(IMT)) and coronary artery calcification(CAC)) and measures of cerebrovascular disease (CVD) in 3 ethnic groups. Methods. A community-based sample of 1331 men and women (47%White European (WE), 36% South Asian (SA) and 16% African Caribbean (AfC)) living in west London (1988–91). At 20 year follow-up (mean age 69.7 ± 6.2), CAC was quantified using CT, carotid IMT was quantified using ultrasound. Cerebral infarcts and white matter hyperintensities (WMH) were identified using MRI. Strokes were identified from primary care record review and hospital discharge data. Results. Stroke was most frequent in AfC. Prevalence of infarcts was similar in all ethnic groups while WMH were most frequent in AfC. Mean carotid IMT(excluding those with plaque) was greatest in AfC. (Table) CAC was greater in WE and SA. In WE, associations between carotid IMT and presence of stroke, infarcts or WMH was strong, even after adjustment for Framingham risk factors and CAC (fully adjusted odds ratio (OR(95%CI)) for a 1 SD increase in IMT:1.34(1.10, 1.64)). However, in SA and AfC there was little association between IMT and CVD (fully adjusted ORs: 1.12(0.87, 1.44), 0.74 (0.51, 1.08) respectively (ethnicity × IMT interactions: P = 0.32 and 0.028 respectively). CAC was independently associated with CVD in WE (fully adjusted OR for 10 unit increment:1.003(1.0004, 1.001), but less so in SA (1.002(1.00, 1.005) or AfC (1.00(0.99, 1.006). Conclusion. Neither carotid IMT nor CAC were independently associated with presence of clinical and subclinical cerebrovascular disease in South Asians or African Caribbeans. In Europeans, IMT was more strongly associated than CAC. *Median (IQR) White Europeans South Asians African Caribbeans Number 630 484 217 Male 77% 86% 52% Smoking (never/ex/current) 38/54/8% 78/18/4% 66/28/6% Treated hypertension 56% 76% 79% Total cholesterol:HDL ratio* 3.5(2.9, 4.2) 3.4(2.8, 4.2) 3.2(2.6, 3.8) Waist:hip ratio* 0.97(0.93, 1.02) 1.00(0.96, 1.04) 28.4(25.6, 31.9) CAC, AU* 97(6,384) 92(7,410) 0.95(0.90, 1.01) CIMT, mm* 0.88(0.76,1.04) 0.89(0.79,1.02) 0.92(0.81,1.04) Carotid lumen diameter, mm 6.61 ± 0.87 6.44 ± 0.76 6.20 ± 0.78 Stroke 4% 5% 9% Brain infarcts, any (MRI 21% 20% 22% White matter hyperintensities 33% 30% 42% Presence of any stroke, infarcts, WMH 37% 37% 47%