title: Systematic reviews of the literature on clipping and coiling of unruptured intracranial aneurysms.
abstract: OBJECTIVE
  The best management of unruptured aneurysms remains controversial. Accurate estimates of treatment-related morbidity and efficacy are needed for clinical decision making.
  
  
  METHODS
  We review recent systematic reviews, case series and population-based studies on clipping and coiling of unruptured aneurysms. A critical analysis of the quality of available studies and of the reliability of results is followed by reappraisal of the logic of clinical research on unruptured aneurysms.
  
  
  RESULTS
  Unfavourable outcome, including death, up to 1 year after surgical clipping, was found in 692 of 9845 patients (REW average: 6.7%; (99%)CI: 4.9-9.0). Unfavourable outcome after coiling occurred in 189 of 5044 patients (REW average 4.8%, ((99%)CI: 3.9-6.0). Location and size of aneurysms were risk factors for clipping, while no risk factor reached statistical significance for coiling studies. The quality of reports was in general poor. Estimates from epidemiological studies showed higher morbidity rates than reviews of case series. Treatment efficacy could not be assessed. All studies are attempts to provide answers to questions that were never properly raised.
  
  
  CONCLUSIONS
  Results of reviews and observational studies should serve as hypotheses for clinical trials.
authors.affiliation: Département de neurochirurgie, VHU Vaudois, Lausanne, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Kotowski
authors.forename: O
authors.initials: O
authors.lastname: Naggara
authors.forename: T E
authors.initials: TE
authors.lastname: Darsaut
authors.forename: J
authors.initials: J
authors.lastname: Raymond
mesh_terms: D004621:Embolization, Therapeutic / Q000379:methods*; D057510:Endovascular Procedures / Q000379:methods*; D006801:Humans; D002532:Intracranial Aneurysm / Q000453:epidemiology / Q000601:surgery / Q000628:therapy*; D018570:Risk Assessment; D012307:Risk Factors; D016896:Treatment Outcome