Subsequently, subgroup analysis of Ki-67 on RFS, showed no heterogeneity in low grade (5 studies, HR = 3.38, 95%CI 2.13 to 5.36, I2 = 13%), but substantial heterogeneity was showed in the low and high grade meningiomas (15 studies, HR = 1.24, 95%CI 1.10 to 1.39, I2 = 82%) or high grade meningiomas (15 studies, HR = 1.40, 95%CI 1.12 to 1.74, I2 = 86%). This evidence concerns the gene MKI67 and meningioma.