Although both anemia (Hb < 100 g/L) and RBC transfusion were predictors of poor outcome (ORs 2.44 and 3.72, 95% CIs 1.67–3.57 and 2.23–6.19, respectively), neither of them was a significant independent predictor when controlling for these and other factors that are likely to affect outcome (Table 5). This evidence concerns the gene GSTM1 and anemia (phenotype).