GSTM1 and anemia (phenotype): The only exception was the lack of an incremental decrement in KDQOL-36 scores at Hb levels < 8 g/dL compared to Hb 10–12 g/dL in exploratory analyses, which might be explained by low patient numbers in this group as well as the limited sensitivity of the KDQOL-36 for common consequences of anemia specifically (fatigue, dizziness, decreased vitality, etc.).