Purpose: To report subgroup analyses of an updated systematic review on endovascular treatment of intracranial unruptured aneurysms (UAs); to compare types of embolic agents, adjunct techniques, and newer devices; and to identify potential risk factors for poor outcomes.
Materials and methods: Meta-Analysis of Observational Studies in Epidemiology and Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were used to prepare this article, and the literature was searched with PubMed and with EMBASE and Cochrane databases. Six eligibility criteria (procedural complications rates; at least 10 patients; saccular, nondissecting UAs; original study published in English or French between January 2003 and July 2011; methodological quality score > 6 [modified Strengthening and Reporting of Observational Studies in Epidemiology criteria]; a study published in a peer-reviewed journal) were used. End points included procedural mortality and unfavorable outcomes (death or modified Rankin Scale, Glasgow Outcome Scale, or World Federation of Neurosurgeons Scale at 1 month scores, all > 2). A fixed-effects model (Mantel-Haenszel) was used for pooled estimates of mortality and unfavorable outcomes; a random-effects model (DerSimonian-Laird) was used in case of heterogeneity.
Results: Ninety-seven studies with 7172 patients (26 studies published July 2008 through July 2011) were included. Sixty-nine (1.8%) of 7034 patients died (fixed-effect weighted average; 99% confidence interval [CI]: 1.4%, 2.4%; Q value, 55.0; I(2) = 0%). Unfavorable outcomes, including death, occurred in 4.7% (242 of 6941) of patients (99% CI: 3.8, 5.7; Q value, 128.3; I(2) = 26.8%). Patients treated after 2004 had better outcomes (unfavorable outcome, 3.1; 99% CI: 2.4, 4.0) than patients treated during 2001-2003 (unfavorable outcome, 4.7%; 99% CI: 3.6%, 6.1%; P = .01) or in 2000 and before (unfavorable outcome, 5.6%; 99% CI: 4.7%, 6.6%; P < .001). Significantly higher risk was associated with liquid embolic agents (8.1%; 99% CI: 4.7%, 13.7%) versus simple coil placement (4.9%; 99% CI: 3.8%, 6.3%; P = .002). Unfavorable outcomes occurred in 11.5% (99% CI: 4.9%, 24.6%) of patients treated with flow diversion.
Conclusion: Procedure-related poor outcomes occurred (4.7% of patients), risks decreased, and liquid embolic agents and flow diversion were associated with higher risks.