MATERIAL and METHODS: We searched MEDLINE, EMBASE, the Cochrane Library and three Chinese domestic electronic databases, namely, Wanfang, CNKI and VIP for studies published between January 1990 and January 2018. We included controlled clinical studies comparing clinical outcomes between surgical clipping and endovascular coiling treatments. Two researchers extracted the data and assessed the quality of the studies, and a meta-analysis was performed using RevMan 5 software.

RESULTS: We analysed a total of 23 controlled clinical studies including 117,796 cases. Meta-analysis demonstrated similar ischaemia rates between clipping and coiling with an odds ratio [OR] of 1.36 (95% CI: 0.77?2.40). The occlusion rate and bleeding risk were higher with clipping than coiling; the pooled ORs were 5.31 (95% CI: 3.07?9.19) and 2.39 (95% CI: 1.82?3.13), respectively. In addition, clipping resulted in a longer hospital stay (OR = 2.90, 95% CI: 2.14?3.65) than coiling did. Patients who underwent clipping had a higher short-term mortality (OR = 1.99, 95% CI: 1.70?2.33) and neurological deficit rate (OR = 2.05, 95% CI: 1.73? 2.44) compared with those who underwent coiling. However, 1 year mortality and deficit rate were similar for both clipping and coiling, with pooled ORs of 0.75 (95% CI: 0.41?1.38) and 0.94 (95% CI: 0.53?1.67), respectively. Funnel plots did not demonstrate a publication bias, with the exception of ischaemic outcome, and sensitivity analysis showed consistent results.

CONCLUSION: Our study demonstrates that coiling is associated with a lower rate of occlusion, shorter hospital stay, lower bleeding risk and lower short-term mortality and morbidity compared with clipping. In terms of ischaemic risk, 1 year mortality and morbidity, coiling and clipping bear a similar risk. In addition, we speculate that surgical clipping may have a better outcome than endovascular coiling in the long term especially in young patients. Further research is needed to confirm our conclusion. Keywords : Unruptured intracranial aneurysms, Surgical clipping, Endovascular coiling, Systematic review