However, significant differences were observed in preoperative Hb level (p = 0.002), preoperative anemia (p = 0.001), Hb decline (p = 0.003), use of PSI (p < 0.001), and the use of tranexamic acid (p < 0.001) among the different medication groups. This evidence concerns the gene GSTM1 and anemia (phenotype).