MATERIAL and METHODS: Through searching the relevant databases, we included eligible studies measuring outcomes with the modified Rankin Scale (mRS), Glasgow Outcome Scale (GOS) and Kim's category. Single group rates were transformed and synthesized to yield the mean weighted probability. Sensitivity analyses were conducted to check the robustness of overall effect. Subgroup analyses were stratified by study type, population, age phase, presentation, surgical procedure and outcome measurement.

RESULTS: The overall estimated rate of good outcome was 0.87 (95%CI, 0.84 0.90), with substantial heterogeneity. In the subgroup analyses, the outcome measured with GOS led to the highest rate of 91%, while Kim's category had the lowest rate of 82%. The combined bypass surgery group resulted in a higher good outcome rate of 0.92 (95%CI, 0.89 0.96) than the indirect bypass group of 0.83% (95%CI, 0.78 0.88).

CONCLUSION: Moyamoya disease after surgical treatment could achieve a good outcome rate of 87%. Kim's category reflected the functional outcome better, resulting in a good outcome rate of 82%. The combined bypass surgery led to better outcomes than indirect bypass. Keywords : Long-term outcome, Meta-analysis, Moyamoya disease, Surgical treatment