Intracranial arterial stenosis in Caucasian versus Chinese patients with TIA and minor stroke: two contemporaneous cohorts and a systematic review

Abstract

Background: Intracranial arterial stenosis (ICAS) is an important cause of stroke worldwide. Separate reports in Caucasians and Asians with stroke/transient ischaemic attack (TIA) have suggested lower ICAS prevalence in Caucasians, but there has been no direct comparisons of the two ethnic groups with the same criteria to define ICAS.

Methods: Acute minor stroke or TIA patients in two cohorts respectively recruiting patients in Oxford (2011-2018, predominantly Caucasians) and Hong Kong (2011-2015, predominantly Chinese) were compared. ICAS was defined as ≥50% stenosis/occlusion in any major intracranial artery in MR/CT angiography. Prevalence, distribution and risk factors of ICAS were compared between the two cohorts. We also systematically reviewed literature on ICAS prevalence in stroke/TIA patients in different populations.

Results: Among 1287 patients from Oxford and 691 from Hong Kong (mean age 69 vs 66), ICAS prevalence was higher in Chinese than in Caucasians (43.0% vs 20.0%; OR 3.02; 95% CI 2.47 to 3.70; p<0.001), independent of age (age-adjusted OR 3.73; 95% CI 3.00 to 4.63; p<0.001) and vascular risk factors (multivariable-adjusted OR 3.21; 95% CI 2.56 to 4.02; p<0.001). This ethnic difference was greater (p interaction=0.005) at age <70 years (OR 5.33; 95% CI 3.79 to 7.50; p<0.001) than at ≥70 years (OR 2.81; 95% CI 2.11 to 3.74; p<0.001). ICAS prevalence increased with age and with vascular risk factors in both cohorts, with equivalent prevalence in Chinese aged <60 years and Caucasians aged ≥80, and in Chinese with no vascular risk factor and Caucasians with two vascular risk factors. ICAS locations also differed between Chinese and Caucasian patients.

Conclusions: Chinese are more susceptible to ICAS than Caucasians, with an earlier onset age and a higher prevalence, independent of vascular risk factors.

Figure 1

Prevalence of ICAS in minor stroke and TIA patients in Caucasians (OXVASC) and Chinese (CUHK-SR) in subgroups. (A) Prevalence of ICAS in OXVASC and CUHK-SR in different age groups; p<0.001 for χ² tests in the comparison between OXVASC and CUHK-SR in each age group. Larger differences in ICAS prevalence are seen in younger patients. (B) Prevalence of ICAS in OXVASC and CUHK-SR by different numbers (0, 1, 2 or 3) of vascular risk factors including histories of hypertension, diabetes and dyslipidaemia; p<0.001 for χ² tests in the comparison between OXVASC and CUHK-SR in subgroups of patients with 0, 1 or 2 vascular risk factors, and p=0.008 in the subgroup of patients with three vascular risk factors.95% CIs of ICAS prevalence in these subgroups are provided within parentheses in the figure. CUHK-SR, the Chinese University of Hong Kong stroke Registry; ICAS, intracranial atherosclerotic stenosis; OXVASC, Oxford vascular study; TIA, transient ischaemic attack; VRFs, number of vascular risk factors.