title: Factors associated with aneurysm size in patients with subarachnoid hemorrhage: effect of smoking and aneurysm location.
abstract: OBJECTIVE
  Intracranial aneurysm size is an important determinant of risk of rupture and outcome after rupture. Risk factors influencing aneurysm formation and growth are not well defined. In this study, we examined the association between known risk factors for cerebrovascular disease and size of intracranial aneurysms in patients with aneurysmal subarachnoid hemorrhage.
  
  
  METHODS
  We analyzed prospectively collected data from the placebo-treated group in a multicenter clinical trial conducted at 54 neurosurgical centers in North America. The presence, location, and size of intracranial aneurysms were determined by review of the admission angiograms. Pertinent information regarding the presence of various cerebrovascular risk factors was collected for each patient. Using logistic regression analysis, we identified independent determinants of aneurysm size from demographic, clinical, and angiographic characteristics of the participants. The impact of aneurysm size on 3-month mortality was analyzed after adjusting for potential confounding factors.
  
  
  RESULTS
  For 298 patients admitted with subarachnoid hemorrhage, the ruptured aneurysms were graded as small (<13 mm) in 235 patients (79%) and large (> or =13 mm) in 63 patients (21%). In the logistic regression model, both smoking at any time (odds ratio, 2.2; 95% confidence interval, 1.1-4.5) and middle cerebral artery origin (odds ratio, 2.5; 95% confidence interval, 1.3-4.9) were independently associated with large aneurysms. Neither hypertension, diabetes mellitus, nor alcohol and illicit drug use were associated with large-sized aneurysms. After adjusting for initial Glasgow Coma Scale score and age in the logistic regression model, the presence of large-sized aneurysms was independently associated with 3-month mortality (odds ratio, 2.3; 95% confidence interval, 1.1-4.8).
  
  
  CONCLUSIONS
  Cigarette smoking and middle cerebral artery origin seem to increase the risk for developing large aneurysms in patients predisposed to intracranial aneurysm formation. Further studies are required to investigate the mechanism underlying the association between cigarette smoking and intracranial aneurysm formation.
authors.affiliation: Department of Neurosurgery, University of Buffalo, New York, USA.
authors.forename: A I
authors.initials: AI
authors.lastname: Qureshi
authors.forename: G Y
authors.initials: GY
authors.lastname: Sung
authors.forename: M F
authors.initials: MF
authors.lastname: Suri
authors.forename: R N
authors.initials: RN
authors.lastname: Straw
authors.forename: L R
authors.initials: LR
authors.lastname: Guterman
authors.forename: L N
authors.initials: LN
authors.lastname: Hopkins
mesh_terms: D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications* / Q000473:pathology*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D013345:Subarachnoid Hemorrhage / Q000209:etiology*