title: Prediction model for 3-year rupture risk of unruptured cerebral aneurysms in Japanese patients.
abstract: OBJECTIVE
  To build a prediction model that estimates the 3-year rupture risk of unruptured saccular cerebral aneurysms.
  
  
  METHODS
  Survival analysis was done using each aneurysm as the unit for analysis. Derivation data were from the Unruptured Cerebral Aneurysm Study (UCAS) in Japan. It consists of patients with unruptured cerebral aneurysms enrolled between 2000 and 2004 at neurosurgical departments at tertiary care hospitals in Japan. The model was presented as a scoring system, and aneurysms were classified into 4 risk grades by predicted 3-year rupture risk: I, < 1%; II, 1 to 3%; III, 3 to 9%, and IV, >9%. The discrimination property and calibration plot of the model were evaluated with external validation data. They were a combination of 3 Japanese cohort studies: UCAS II, the Small Unruptured Intracranial Aneurysm Verification study, and the study at Jikei University School of Medicine.
  
  
  RESULTS
  The derivation data include 6,606 unruptured cerebral aneurysms in 5,651 patients. During the 11,482 aneurysm-year follow-up period, 107 ruptures were observed. The predictors chosen for the scoring system were patient age, sex, and hypertension, along with aneurysm size, location, and the presence of a daughter sac. The 3-year risk of rupture ranged from <1% to >15% depending on the individual characteristics of patients and aneurysms. External validation indicated good discrimination and calibration properties.
  
  
  CONCLUSIONS
  A simple scoring system that only needs easily available patient and aneurysmal information was constructed. This can be used in clinical decision making regarding management of unruptured cerebral aneurysms.
authors.affiliation: Department of Health Informatics, Kyoto University School of Public Health, Kyoto.
authors.forename: Shinjiro
authors.initials: S
authors.lastname: Tominari
authors.affiliation: Unruptured Cerebral Aneurysm Study Japan Coordinating Office, University of Tokyo, Tokyo.|Department of Neurological Surgery, Nippon Medical School, Tokyo.
authors.forename: Akio
authors.initials: A
authors.lastname: Morita
authors.affiliation: Division of Endovascular Neurosurgery, Department of Neurosurgery, Jikei University School of Medicine, Tokyo.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Ishibashi
authors.affiliation: Department of Neurosurgery, National Hospital Organization, Mito Medical Center, Ibaraki.
authors.forename: Tomosato
authors.initials: T
authors.lastname: Yamazaki
authors.affiliation: Division of Endovascular Neurosurgery, Department of Neurosurgery, Jikei University School of Medicine, Tokyo.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Takao
authors.affiliation: Division of Endovascular Neurosurgery, Department of Neurosurgery, Jikei University School of Medicine, Tokyo.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Murayama
authors.affiliation: Department of Neurosurgery, National Hospital Organization, Mito Medical Center, Ibaraki.
authors.forename: Makoto
authors.initials: M
authors.lastname: Sonobe
authors.affiliation: Department of Neurosurgery, National Hospital Organization, Nagasaki Medical Center, Nagasaki.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yonekura
authors.affiliation: Department of Neurosurgery, University of Tokyo, Tokyo.
authors.forename: Nobuhito
authors.initials: N
authors.lastname: Saito
authors.affiliation: Department of Neurosurgery, Kyorin University School of Medicine, Tokyo.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Shiokawa
authors.affiliation: Department of Neurological Surgery, Okayama University Graduate School of Medicine, Okayama.
authors.forename: Isao
authors.initials: I
authors.lastname: Date
authors.affiliation: Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai.
authors.forename: Teiji
authors.initials: T
authors.lastname: Tominaga
authors.affiliation: Department of Neurosurgery, Shiga University of Medical Science, Otsu.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Nozaki
authors.affiliation: Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo.
authors.forename: Kiyohiro
authors.initials: K
authors.lastname: Houkin
authors.affiliation: Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto.
authors.forename: Susumu
authors.initials: S
authors.lastname: Miyamoto
authors.affiliation: National Hospital Organization, Tokyo.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Kirino
authors.affiliation: Shinsapporo Neurosurgical Hospital, Sapporo, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Hashi
authors.affiliation: Department of Health Informatics, Kyoto University School of Public Health, Kyoto.
authors.forename: Takeo
authors.initials: T
authors.lastname: Nakayama
mesh_terms: D000368:Aged; D017542:Aneurysm, Ruptured / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002532:Intracranial Aneurysm / Q000175:diagnosis / Q000453:epidemiology*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011379:Prognosis; D015203:Reproducibility of Results; D012306:Risk