The decline of mean Hb values during SAH was also associated with the primary endpoints—cerebral vasospasm (∆ = 0.87 g/dL, 95% CI 0.67–1.06, p < 0.0001, I2 = 0%), cerebral infarction (∆ = 0.73 g/dL, 95% CI 0.53–0.94, p < 0.0001, I2 = 37%), and poor outcome at long-term follow-up (∆ = 0.82 g/dL, 95% CI 0.51–1.13, p < 0.0001, I2 = 76%). Here, GSTM1 is linked to cerebral infarction.