GSTM1 and anemia (phenotype): The mean haemoglobin concentration at baseline was 12.5 g/dL (95 % CI 12.3–12.78) and 12.5 g/dL (95 % CI 12.3–12.8) at day 28, the risk of anaemia (Hb < 10 g/dL) being 18.5 % (51/175) and 16.4 % (35/214) at baseline and at day 28 respectively.