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

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

We identified all hospitalized patients ( ≥ 18 years) who were admitted with a primary diagnosis of ischemic stroke (International Classification of Diseases, Ninth Revision codes 433, 434, 436) for the first time between 2000 and 2011. A prior study validating the diagnosis of acute ischemic stroke in National Health Insurance claims data using the Taiwan Stroke Registry as a reference revealed a positive predictive value of 88.4% and sensitivity of 97.3%. 11 Another cross-sectional study showed that among confirmed cases of acute ischemic stroke in a hospital medical record, 94.5% were assigned 'ischemic stroke' as the principal diagnosis in the NHIRD. 12 We only enrolled patients receiving brain computed tomography (CT) or magnetic resonance imaging (MRI) during hospitalization with the assumption that all patients with symptoms of acute stroke should receive brain imaging. This approach was intended to exclude stroke patients who were hospitalized for rehabilitation during chronic stage. Although brain imaging, especially CT, may not be able to reveal the cerebral infarction in patients with symptoms or signs of acute stroke, it can easily exclude intracranial hemorrhage. Thus NHIRD had a low probability of misclassifying hemorrhagic stroke into ischemic stroke if brain imaging was done.