title: Effect of seasonal and monthly variation in weather and air pollution factors on stroke incidence in Seoul, Korea.
abstract: OBJECTIVE
  The purpose of the present study was to determine whether seasonal and monthly variations in stroke incidence exist and whether they are related to meteorologic and air pollution parameters under similar weather and environmental conditions in selected areas of Seongdong district, Seoul, South Korea.
  
  
  METHODS
  From January 1, 2004, to December 31, 2013, 3001 consecutive stroke events were registered in residents of selected areas of Seongdong district, Seoul, South Korea. The authors calculated the stroke attack rate per 100,000 people per month and the relative risk of stroke incidence associated with meteorologic and air pollution parameters. We also analyzed odds ratios with a 95% confidence interval for seasonal and monthly stroke incidence.
  
  
  RESULTS
  The incidence of stroke in September was significantly higher (odds ratio, 1.233; 95% confidence interval, 1.042-1.468) compared with January. The seasonal ischemic stroke incidence in summer (odds ratio, 1.183; 95% confidence interval, 1.056-1.345) was significantly higher than in winter, whereas the seasonal incidence of intracerebral hemorrhage relative to winter was not significant. The mean temperature was positively correlated with ischemic stroke (relative risk, 1.006; P=0.003), and nitrogen dioxide (relative risk, 1.262; P=0.001) showed a strong positive correlation with intracerebral hemorrhage incidence among the older age group.
  
  
  CONCLUSIONS
  We demonstrated distinct patterns of seasonal and monthly variation in the incidence of stroke and its subtypes through consideration of the meteorologic and air pollution parameters. We therefore expect that these findings may enhance our understanding of the relationships between stroke and weather and pollutants.
authors: From the Department of Neurosurgery (M.-H.H., H.-J.Y., Young-Soo Kim), and Department of Neurology (Young-Seo Kim), Hanyang University Medical Center, Seoul, Korea.
authors: Myung-Hoon
authors: MH
authors: Han
authors: From the Department of Neurosurgery (M.-H.H., H.-J.Y., Young-Soo Kim), and Department of Neurology (Young-Seo Kim), Hanyang University Medical Center, Seoul, Korea. hjyi8499@hanyang.ac.kr.
authors: Hyeong-Joong
authors: HJ
authors: Yi
authors: From the Department of Neurosurgery (M.-H.H., H.-J.Y., Young-Soo Kim), and Department of Neurology (Young-Seo Kim), Hanyang University Medical Center, Seoul, Korea.
authors: Young-Soo
authors: YS
authors: Kim
authors: From the Department of Neurosurgery (M.-H.H., H.-J.Y., Young-Soo Kim), and Department of Neurology (Young-Seo Kim), Hanyang University Medical Center, Seoul, Korea.
authors: Young-Seo
authors: YS
authors: Kim
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000397:Air Pollution / Q000009:adverse effects* / Q000706:statistics & numerical data; D002543:Cerebral Hemorrhage / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009585:Nitrogen Dioxide / Q000009:adverse effects*; D012042:Registries / Q000706:statistics & numerical data; D018570:Risk Assessment; D012621:Seasons; D066106:Seoul / Q000453:epidemiology; D020521:Stroke / Q000453:epidemiology / Q000209:etiology*; D013696:Temperature; D014887:Weather
chemical_list: D009585:Nitrogen Dioxide
keywords: incidence; stroke; temperature