Trends in Incident and Recurrent Rates of First-Ever Ischemic Stroke in Taiwan between 2000 and 2011

Lee, Meng; Wu, Yi-Ling; Ovbiagele, Bruce

It is informative to compare the trends in stroke incidence, recurrence, and management of stroke in Taiwan with data from other Asian countries, such as Korea. Among hospital admissions with stroke as the primary diagnostic code during 2001 to 2009, hospitalizations for ischemic stroke increased substantially in Korea. 16 This apparent rise in annual ischemic stroke incidence in Korea was likely due to an increase in the country's elderly population. 16 However, the median age of the current study in Taiwan did not change during the study period. Moreover, a comparison of survey data obtained in 2002 vs. 1993-1996 showed a significant improvement in hypertension awareness, treatment, and control in Taiwan, which may have contributed to its declining incidence of ischemic stroke. 17 Ischemic stroke incidence in the population aged 35-74 years was 226 per 100,000 person-years (including first-ever and recurrent ischemic stroke) in Korea 146 per 100,000 persons in our population aged 18 years or older (first-ever ischemic stroke only); while the annual rate of recurrent ischemic stroke was about 5.0% in Japan during 2007 to 2009 vs. a 7.7% annual recurrent stroke (ischemic or hemorrhagic) rate noted in Taiwan. 18 In the Fukuoka ischemic stroke registry, mean age was 70 years, 76% had hypertension, 27% diabetes mellitus, 46% hyperlipidemia, and 26% atrial fibrillation. 19 Our study had similar frequencies of stroke risk factors except only 10% patients had atrial fibrillation in this study. Since diagnosis of atrial fibrillation in hospitalized ischemic stroke patients typically relies on a single baseline 12-lead electrocardiogram or history of atrial fibrillation, it is conceivable that the frequency of paroxysmal atrial fibrillation in admitted ischemic stroke patients in Taiwan might be underestimated. Among ischemic stroke patients with atrial fibrillation in this study, 34% vs. 10% in a Chinese ischemic stroke registry, 20 received oral anticoagulants during hospitalization. The underuse of oral anticoagulant therapy in eligible Asian stroke patients during hospitalization may in part be due to concerns about hemorrhagic transformation. Also, 31% patients received statin therapy in this study at discharge vs. 35% in Fukuoka stroke registry, which is highly comparable. 21 As compared to a prior study based on the control arms of clinical trials for secondary stroke prevention, the current study had higher recurrent rate of stroke (8% vs. 5% 10 ). The difference may exist in the prior study excluded patients with atrial fibrillation or severe carotid stenosis 10 while this study included all first-ever ischemic stroke patients. Also, people participating in clinical trials may receive more rigorous risk factors control, which turns out to have lower recurrent stroke. Furthermore, the current study enrolled patients in the acute stage when the risk of recurrent stroke is high, whereas secondary stroke prevention trials, in general, enrolled patients after the acute stage. We found the one-year recurrent stroke was declining from 2000 to 2011, which may be explained by increasing use of statin (8.8% to 30.8%), antiplatelet agents (76.1% to 86.6%), and oral anticoagulant agents in atrial fibrillation (30.0% to 34.5%) during hospitalization among this period of time.