title: Incidence of aneurysmal subarachnoid hemorrhage in Norway, 1999-2007.
abstract: OBJECTIVE
  To investigate changes and regional variations in annual incidence rates of aneurysmal subarachnoid hemorrhage (SAH) in Norway between 1999 and 2007.
  
  
  METHODS
  The authors retrospectively reviewed data from the Norwegian Patient Register for the period 1999-2007.
  
  
  RESULTS
  Crude incidence of aneurysmal SAH was 10.0/100,000 person years [95% CI (confidence interval): 9.7-10.3] and was higher in women (12.0/100,000 person years; 95% CI: 11.5-12.5) than men (8.1/100,000 person years; 95% CI: 7.7-8.4). Decreasing annual incidence rates were observed from 11.1/100,000 person years (95% CI: 10.5-11.6) in the period 1999-2001 to 8.9/100,000 person years (95% CI: 8.4-9.4) in the period 2005-2007 (P for trend <0.001). Regional variations were observed, from 8.4/100,000 person years (95% CI: 7.7-9.00) in the southern region, 10.4/100,000 person years (95% CI: 9.5-11.2) in the central region and 11.9/100,000 person years (95% CI: 10.8-12.9) in the northern region.
  
  
  CONCLUSIONS
  Incidence of aneurysmal SAH in Norway decreased from 1999 to 2007, with significant regional variations indicating an increasing gradient from south to north.
authors.affiliation: Department of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway.
authors.forename: H M
authors.initials: HM
authors.lastname: Lindekleiv
authors.forename: I
authors.initials: I
authors.lastname: Njølstad
authors.forename: T
authors.initials: T
authors.lastname: Ingebrigtsen
authors.forename: E B
authors.initials: EB
authors.lastname: Mathiesen
mesh_terms: D000367:Age Factors; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D015994:Incidence; D038801:International Classification of Diseases; D008297:Male; D009664:Norway / Q000453:epidemiology; D012189:Retrospective Studies; D012737:Sex Factors; D013345:Subarachnoid Hemorrhage / Q000453:epidemiology*