GSTM1 and anemia (phenotype): The results of the study indicate that Hb in patients with SAH should be monitored closely and corrected (if Hb<95g/L), and suggest a liberal transfusion threshold may be beneficial; however, further evidence is required to ensure that blood transfusion is the optimal method to treat anaemia in this population of patients and further study into the causative effect between anaemia and increased mortality and morbidity is required.