GSTM1 and anemia (phenotype): Seventy-four patients (13.9%) were readmitted to hospital but neither preoperative or discharge anaemia was associated (51.4% vs. 45.6%, Hb 129 g/L ± 19 vs. 130 g/L ± 19, p = 0.361 and 80.8% vs. 75.9%, 114 g/L ± 16 vs. 117 g/L ± 14, p = 0.360 respectively).