Risk of stroke and intracranial hemorrhage in 9727 Chinese with atrial fibrillation in Hong Kong

BACKGROUND Current risk schemes to predict ischemic stroke and intracranial hemorrhage (ICH) in atrial fibrillation (AF) are derived primarily using a Caucasian population. OBJECTIVE The purpose of this study was to describe the risk of ischemic stroke and ICH in a large contemporary "real world" cohort of Chinese AF patients in Hong Kong with detailed long-term follow-up. METHODS This observational study used a hospital-based cohort of Chinese patients with nonvalvular AF. RESULTS Among 9727 patients with nonvalvular AF (age 76.9 +/- 12.5 years, 52.1% female), 3881 patients (39.9%) did not receive antithrombotic therapy, 3934 patients (40.4%) were taking aspirin, and 1912 (19.7%) were taking warfarin. After mean follow-up of 3.19 years, 847 patients (21.8%) without antithrombotic therapy developed ischemic strokes (annual risk 9.28%, 95% confidence interval [CI] 8.89%-9.70%). There was a progressively increase in annual risk of ischemic stroke with increasing CHADS(2) and CHA(2)DS(2)VASc scores. The c-statistics revealed that CHA(2)DS(2)-VASc scores (0.525, 95% CI 0.509-0.541, P = .017) was better than CHADS(2) scores (0.506, 95% CI 0.490-0.522, P = .584) in predicting ischemic stroke. Use of aspirin and of warfarin were associated with reduced annual risk of ischemic stroke by 18.7% and 52.7%, respectively (P < .05). The annual incidence of ICH in patients taking aspirin and warfarin was 0.77% per year and 0.80% per year, respectively. The adjusted net clinical benefit favored warfarin over aspirin or no therapy for almost all Chinese AF patients CHA(2)DS(2)-VASc score >1. CONCLUSION Chinese AF patients are at high risk for ischemic stroke. Analysis of the net clinical benefit favors the use of warfarin over aspirin or no therapy for stroke prevention in a broad range of Chinese AF patients.