GSTM1 and anemia: In addition, patients who were transfused intraoperatively had lower preoperative Hb levels (12.4 [IQR, 11.5–13.7] vs. 12.9 [IQR, 12.1–14.1]; p < 0.001) and were more likely to have mild (n = 86, 29.0% vs. n = 291, 26.0%) or severe (n = 47, 16.0% vs. n = 103, 9.2%) anemia versus patients who were not transfused (p < 0.001) (Table 1).