Geotopographic and Environmental Characteristics of Communities and the Seasonality of Stroke Occurrences

We read with great interest the study by Takizawa et al that was recently published in the Journal of Stroke and Cerebrovascular Diseases describing seasonality in the occurrence of stroke in Japan. The authors analyzed 35,631 registered stroke cases (29,238 ischemic and 6,393 hypertensive hemorrhagic stroke patients) occurring between 1998 and 2007 from the Japanese Standard Stroke Registry Study (JSSRS) database, which is currently the world’s largest hospital-based stroke database, accumulating records from 163 Japanese institutions throughout Japan. To examine seasonal variation in the incidence of ischemic and nonischemic stroke patients, months were grouped into 4 seasons: spring (March to May), summer (June to August), fall (September to November), and winter (December to February). The authors did not observe any statistically significant seasonal difference in the incidence of ischemic stroke, but the incidence in summer was significantly higher than in winter (incidence ratio 1.035). Regarding the seasonal variation in subtypes of ischemic stroke, lacunar stroke showed significant seasonality with the incidence of summer being significantly higher than in winter (incidence ratio 1.187). Atherothrombotic stroke showed a similar pattern but did not reach statistical significance. Significant seasonality was observed for cardioembolic stroke but for this subtype the incidence in winter was significantly higher than in summer (incidence ratio 1.128). Seasonal differe...
Source: Journal of Stroke and Cerebrovascular Diseases - Category: Neurology Authors: Tags: Letter to the Editor Source Type: research