Risk factors and incidence of ischemic stroke in Taiwanese with nonvalvular atrial fibrillation-A nation wide database analysis

Background: : Atrial fibrillation (AF) is a risk factor for ischemic stroke. Stroke-prevention strategies based on risk schemes have been developed but most of the data are from western people. Our goal is to investigate the risk factors of ischemic stroke in Taiwanese with AF in a nation-wide database. Methods: : A universal national health insurance (NHI) program has been implemented in Taiwan since 1995. We used system sampling database from 1997 to 2008 with a total of 1,000,000 subjects. By using ambulatory and inpatient claim data, we included subjects with AF and were above 20 years old. We excluded those who had ever taken warfarin or aspirin or had valvular heart diseases. Result: : A total of 7920 patients (3633 women, 4287 men) were included in the final analyses. Cox regression analysis showed that the risk factors for ischemic stroke were age (OR = 1.338 for age 65-74 years vs. age 20-64 years, P = 0.014; OR = 1.652 for age over 75 years vs. age 20-64years, P < 0.001), hypertension (HTN) (OR = 2.656, P < 0.001), diabetes mellitus (DM) (OR = 1.341, P = 0.005), heart failure (OR = 1.611, P < 0.001), previous ischemic stroke or transient ischemic accident (TIA) ( OR = 2.752, P < 0.001) and peripheral arterial disease (PAD) (OR = 1.814, P = 0.006). The gender, coronary artery disease, history of myocardial infarction and chronic renal insufficiency were not associated with ischemic stroke. The rate of ischemic stroke was much lower in current cohort as compared with that in whites. Frequent used risk schemes including CHADS(2) and CHA(2)DS(2)-VASC had comparable but only limited ability to predict ischemic stroke in subjects with AF. Conclusion: : Compare with western people, hypertension plays a more important role in ischemic stroke in Taiwanese with AF and the incidence is lower. A substantial number of ischemic strokes cannot be accurately predicted by current risk schemes. (C) 2011 Elsevier Ireland Ltd. All rights reserved.