title: Endovascular treatment of intracranial unruptured aneurysms: systematic review and meta-analysis of the literature on safety and efficacy.
abstract: OBJECTIVE
  To report an updated, systematic review of medical literature from January 2003 to July 2008, on endovascular treatment (EVT) of intracranial unruptured aneurysms (UAs) (a) to assess the morbidity and case fatality rate of EVT of UAs, (b) to understand how bias can affect results, and (c) to estimate the efficacy of EVT by using reported digital subtraction angiographic (DSA) results and clinical follow-up events.
  
  
  METHODS
  This article was prepared in accordance with the Meta-Analysis of Observational Studies in Epidemiology and Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The literature was searched by using PubMed and the EMBASE and Cochrane Library databases. Eligibility criteria were (a) explicit procedural mortality and morbidity rates; (b) at least 10 patients; (c) saccular, intradural, nondissecting UAs; (d) original study published in English or French between January 2003 and July 2008; and (e) a methodological quality score higher than 6, according to Strengthening the Reporting of Observational Studies in Epidemiology criteria. End points included procedural mortality and morbidity, defined as a modified Rankin scale score of 3-6 at 1 month, and efficacy, estimated by using immediate and follow-up digital subtraction angiographic results, as well as delayed hemorrhagic events.
  
  
  RESULTS
  Seventy-one studies were included. Procedural unfavorable outcome was found in 4.8% (random-effect weighted average; 189 of 5044) of patients (99% confidence interval [CI]: 3.9%, 6.0%). Immediate angiographic results showed satisfactory occlusion in 86.1% (2660 of 3089) of UAs. Recurrences were shown in 321 (24.4%) of 1316 patients followed up for 0.4-3.2 years. Retreatment was performed in 9.1% (random-effect weighted average; 166 of 1699) of patients (99% CI: 6.2%, 13.1%). The annual risk of bleeding after EVT was 0.2% (random-effect weighted average; nine of 1395) of patients (99% CI: 0.1%, 0.3%), but clinical follow-up was short, limited to the first 6 months for 76.7% (n = 1071) of reported patients.
  
  
  CONCLUSIONS
  EVT of UAs can be performed with relative safety. The efficacy of treatment as compared with observation has not been rigorously documented.
authors.affiliation: International Consortium of Neuroendovascular Centres, Interventional Neuroradiology Research Unit, Department of Radiology, University of Montreal, CHUM-Notre-Dame Hospital, Montreal, QC, Canada.
authors.forename: Olivier N
authors.initials: ON
authors.lastname: Naggara
authors.forename: Phil M
authors.initials: PM
authors.lastname: White
authors.forename: François
authors.initials: F
authors.lastname: Guilbert
authors.forename: Daniel
authors.initials: D
authors.lastname: Roy
authors.forename: Alain
authors.initials: A
authors.lastname: Weill
authors.forename: Jean
authors.initials: J
authors.lastname: Raymond
mesh_terms: D015901:Angiography, Digital Subtraction; D002533:Cerebral Angiography / Q000379:methods*; D004621:Embolization, Therapeutic / Q000379:methods* / Q000401:mortality; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000401:mortality / Q000628:therapy*; D010043:Outcome and Process Assessment, Health Care