LAUSR

Background: Despite numerous reports indicating ethnic difference in intracranial arterial stenosis (ICAS) between Caucasians and Asians, there has been no direct comparison in disease burden and clinical correlates of ICAS in stroke patients in the two populations with the same criteria to define ICAS. Methods: Acute minor stroke or transient ischemic attack patients who received cerebral MR/CT angiography exam in two cohorts were analyzed: Oxford Vascular Study (OXVASC, 2011-2018) with predominantly Caucasians, and the Chinese University of Hong Kong (CUHK) stroke registry (2011-2015) with predominantly Chinese. ICAS was defined as ≥50% stenosis in any major intracranial artery in MR/CT angiography. Interobserver agreement between 2 investigators for presence of ICAS was assessed in 50 cases with Cohen’s kappa. We compared the burden and risk factors of ICAS in the two cohorts. Results: Overall, 1,287 patients from OXVASC (mean age 69 years) and 640 from the CUHK cohort (mean age 66 years) were analyzed. Interobserver agreement for presence of ICAS was good (kappa=0.82). Prevalence of ICAS was significantly higher in Chinese than in Caucasians: 43.6% in the CUHK cohort versus 20.0% in OXVASC (crude OR 3.10; age-adjusted OR 3.81, 95% CI 3.06-4.75; p<0.001). Mean ages of patients with ICAS in the two cohorts were 75 and 68 years, respectively. The difference between Caucasians and Chinese in ICAS prevalence was smaller in those aged ≥70 years (28.1% versus 51.9%) than those <70 years (9.8% versus 38.0%) (Figure). ICAS shared similar risk factors in the two cohorts, including older age, and history of hypertension and diabetes. Conclusions: Chinese are more susceptible to ICAS, with an earlier onset age than Caucasians, but the ICAS burden in Caucasians was higher than previously estimated, especially in older patients.