According to Parfrey's meta-analysis9, in patients with severe anaemia before treatment (at baseline) (defined as a concentration of Hb < 10g/dL, with the average baseline Hb concentration in each study as low as 5.9 g/dL), increasing the concentration of Hb to ≤ 12g/dL by ESA could significantly reduce the left ventricular mass index (LVMI). This evidence concerns the gene GSTM1 and anemia (phenotype).