title: Risk factors for the formation and rupture of intracranial saccular aneurysms in Shimane, Japan.
abstract: BACKGROUND
  Prevention of aneurysmal subarachnoid hemorrhage (SAH) can be achieved by reducing risk factors, which include those for aneurysm formation and aneurysm rupture. However, neither of these 2 factors has been discussed separately so far. A case control study was undertaken in Shimane, Japan, to identify modifiable risk factors for the formation and rupture of aneurysms.
  
  
  METHODS
  This study included 858 patients with ruptured aneurysms, 285 patients with unruptured aneurysms without a history of SAH, and 798 control subjects. Hypertension, diabetes mellitus, heart disease, hypercholesterolemia, cigarette smoking, and alcohol consumption were assessed as risk factors by using conditional logistic regression.
  
  
  RESULTS
  After adjustment for other risk factors, hypertension was the most powerful risk factor for aneurysm formation, regardless of age and sex, followed by hypercholesterolemia, heart disease, and cigarette smoking, whereas diabetes mellitus and daily drinking were insignificant for aneurysm formation. Hypertension and daily drinking were not related to the risk of aneurysm rupture, regardless of age and sex, whereas cigarette smoking was associated with an increased risk of aneurysm rupture in patients 60 years or older and in men. In contrast, hypercholesterolemia was strongly associated with a decreased risk of rupture, regardless of age and sex, and in patients with small aneurysms (<5 mm). Diabetes mellitus and heart disease were also related to a decreased risk of rupture in patients 60 years or older and in women.
  
  
  CONCLUSIONS
  Identification of risk factors for aneurysm formation and rupture separately seems to be pivotal for reducing the incidence of SAH.
authors.affiliation: Department of Neurosurgery, Shimane Prefectural Central Hospital, Izumo 693-8555, Japan. norosan@leaf.ocn.ne.jp
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Inagawa
mesh_terms: D000367:Age Factors; D000368:Aged; D017542:Aneurysm, Ruptured / Q000209:etiology* / Q000473:pathology / Q000628:therapy; D016022:Case-Control Studies; D002391:Catchment Area, Health; D015331:Cohort Studies; D005260:Female; D015438:Health Behavior; D006304:Health Status; D006801:Humans; D002532:Intracranial Aneurysm / Q000209:etiology* / Q000473:pathology / Q000628:therapy; D007564:Japan; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012737:Sex Factors