title: Risk Analysis of Unruptured Intracranial Aneurysms: Prospective 10-Year Cohort Study.
abstract: OBJECTIVE
  The natural history of unruptured intracranial aneurysms remains unclear, and management strategy is not well defined.
  
  
  METHODS
  From January 2003 to December 2012, we enrolled patients with aneurysm in our institution. In total, 2252 patients with 2897 aneurysms were eligible for analysis, and 1960 eligible aneurysms were conservatively managed. Precise 3-dimensional evaluation was conducted using computed tomography angiography, digital subtraction angiography, or magnetic resonance angiography. We then assessed the risk of aneurysm rupture, mortality, and morbidity associated with aneurysm characteristics, demographics, and known health/lifestyle risk factors.
  
  
  RESULTS
  The mean follow-up duration was 7388 aneurysm-years. During observation, 56 aneurysms ruptured, resulting in an overall rupture rate per year of 0.76% (95% confidence interval, 0.58-0.98). The mean initial visit to rupture interval was 547 days. Aneurysm size, location, daughter sac, and history of subarachnoid hemorrhage were significant independent predictors for aneurysm rupture. Aneurysms that were ≥5 mm were associated with a significantly increased risk of rupture when compared with 2- to 4-mm aneurysms (unadjusted hazard ratio, 12.24; 95% confidence interval, 7.15-20.93). Of 56 patients who experienced hemorrhage, 29 (52 %) died or were rendered severely disabled. Of the patients who had large or giant aneurysms, none recovered without deficits, and the mortality rate after rupture was 69%. For aneurysms sized <5 mm, the mortality rate was 18%.
  
  
  CONCLUSIONS
  Larger aneurysms are at greater risk for rupture and poor outcome. Ethnic factors may play a role in the risk of rupture.
authors.affiliation: From the Division of Endovascular Neurosurgery, Department of Neurosurgery (Y.M., H.T., T.I., T.S., M.E., I.Y., H.A., K.I.) and Division of Molecular Epidemiology (M.U.), The Jikei University School of Medicine, Tokyo, Japan; and Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom (A.J.M.). ymurayama@jikei.ac.jp.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Murayama
authors.affiliation: From the Division of Endovascular Neurosurgery, Department of Neurosurgery (Y.M., H.T., T.I., T.S., M.E., I.Y., H.A., K.I.) and Division of Molecular Epidemiology (M.U.), The Jikei University School of Medicine, Tokyo, Japan; and Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom (A.J.M.).
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Takao
authors.affiliation: From the Division of Endovascular Neurosurgery, Department of Neurosurgery (Y.M., H.T., T.I., T.S., M.E., I.Y., H.A., K.I.) and Division of Molecular Epidemiology (M.U.), The Jikei University School of Medicine, Tokyo, Japan; and Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom (A.J.M.).
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Ishibashi
authors.affiliation: From the Division of Endovascular Neurosurgery, Department of Neurosurgery (Y.M., H.T., T.I., T.S., M.E., I.Y., H.A., K.I.) and Division of Molecular Epidemiology (M.U.), The Jikei University School of Medicine, Tokyo, Japan; and Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom (A.J.M.).
authors.forename: Takayuki
authors.initials: T
authors.lastname: Saguchi
authors.affiliation: From the Division of Endovascular Neurosurgery, Department of Neurosurgery (Y.M., H.T., T.I., T.S., M.E., I.Y., H.A., K.I.) and Division of Molecular Epidemiology (M.U.), The Jikei University School of Medicine, Tokyo, Japan; and Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom (A.J.M.).
authors.forename: Masaki
authors.initials: M
authors.lastname: Ebara
authors.affiliation: From the Division of Endovascular Neurosurgery, Department of Neurosurgery (Y.M., H.T., T.I., T.S., M.E., I.Y., H.A., K.I.) and Division of Molecular Epidemiology (M.U.), The Jikei University School of Medicine, Tokyo, Japan; and Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom (A.J.M.).
authors.forename: Ichiro
authors.initials: I
authors.lastname: Yuki
authors.affiliation: From the Division of Endovascular Neurosurgery, Department of Neurosurgery (Y.M., H.T., T.I., T.S., M.E., I.Y., H.A., K.I.) and Division of Molecular Epidemiology (M.U.), The Jikei University School of Medicine, Tokyo, Japan; and Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom (A.J.M.).
authors.forename: Hideki
authors.initials: H
authors.lastname: Arakawa
authors.affiliation: From the Division of Endovascular Neurosurgery, Department of Neurosurgery (Y.M., H.T., T.I., T.S., M.E., I.Y., H.A., K.I.) and Division of Molecular Epidemiology (M.U.), The Jikei University School of Medicine, Tokyo, Japan; and Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom (A.J.M.).
authors.forename: Koreaki
authors.initials: K
authors.lastname: Irie
authors.affiliation: From the Division of Endovascular Neurosurgery, Department of Neurosurgery (Y.M., H.T., T.I., T.S., M.E., I.Y., H.A., K.I.) and Division of Molecular Epidemiology (M.U.), The Jikei University School of Medicine, Tokyo, Japan; and Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom (A.J.M.).
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Urashima
authors.affiliation: From the Division of Endovascular Neurosurgery, Department of Neurosurgery (Y.M., H.T., T.I., T.S., M.E., I.Y., H.A., K.I.) and Division of Molecular Epidemiology (M.U.), The Jikei University School of Medicine, Tokyo, Japan; and Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom (A.J.M.).
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Molyneux
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017542:Aneurysm, Ruptured / Q000453:epidemiology* / Q000401:mortality; D015901:Angiography, Digital Subtraction; D002533:Cerebral Angiography; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D002532:Intracranial Aneurysm / Q000175:diagnosis* / Q000453:epidemiology; D008137:Longitudinal Studies; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012306:Risk; D012307:Risk Factors; D012422:Rupture, Spontaneous / Q000453:epidemiology* / Q000401:mortality; D013345:Subarachnoid Hemorrhage / Q000453:epidemiology*; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: aneurysm, ruptured; angiography, digital subtraction; natural history; risk factors