title: Seasonal variation in the occurrence of stroke in Northern Greece: a 10 year study in 8204 patients.
abstract: OBJECTIVE
  The effect of seasonal variation on the occurrence of stroke remains controversial. The objective of this study was to determine whether there is a seasonal variation in the occurrence of stroke in Northern Greece.
  
  
  METHODS
  We recorded the seasonal stroke rates over a 10 year period (from January 1997 to December 2006) in 8204 patients in Northern Greece. The findings were analysed separately for ischemic stroke (IS), intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH) and transient ischemic attack (TIA).
  
  
  RESULTS
  In patients with IS, there was a significant seasonal variation (p<0.001), with the peak incidence in spring (8.4% above average) and the lowest rate in summer (10.4% below average). There was no significant seasonal variation in the occurrence of the other stroke subtypes (ICH, SAH and TIA) when they were considered individually.
  
  
  CONCLUSIONS
  The seasonal effect on stroke incidence needs to be defined so as to improve the provision of preventive measures.
authors.affiliation: Second Propedeutic Department of Internal Medicine, Medical School, Aristotle University of Thessaloniki, Hippokration Hospital, Thessaloniki, Greece.
authors.forename: Asterios
authors.initials: A
authors.lastname: Karagiannis
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Tziomalos
authors.forename: Dimitri P
authors.initials: DP
authors.lastname: Mikhailidis
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Semertzidis
authors.forename: Evangelia
authors.initials: E
authors.lastname: Kountana
authors.forename: Anna I
authors.initials: AI
authors.lastname: Kakafika
authors.forename: Efstathios D
authors.initials: ED
authors.lastname: Pagourelias
authors.forename: Vasilios G
authors.initials: VG
authors.lastname: Athyros
mesh_terms: D000368:Aged; D005260:Female; D006115:Greece / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012621:Seasons; D020521:Stroke / Q000453:epidemiology*