GSTM1 and anemia (phenotype): When compared to patients without baseline anemia, those patients from the Hb-R subgroup had a similar functional improvement (OR 0.98, P = 0.98), whereas patients from the Hb-NR subgroup had a significantly lower likelihood of functional improvement with ≧2 NYHA classes (OR 0.49, P = 0.034; Figure 4C).