MMP9 and brain edema: Meta-analysis indicated higher levels of MMP-9 in patients with severe brain edema (SMD, 0.76; 95% CI, 0.18-1.35; four studies, 419 patients) and hemorrhagic transformation (SMD, 1.00; 95% CI, 0.41-1.59; 11 studies, 1,709 patients) but not poor outcome (SMD, 0.30; 95% CI, -0.12 to 0.72; four studies, 759 patients).