GSTM1 and anemia (phenotype): The prevalence of severe anaemia (Hb < 6 g/dL) was 1.07% and 0.32%, prevalence ratio 0.30 (95% CI 0.07–1.19) in 2008 and 1.0% and 2.2%, prevalence ratio 2.1 (95% CI 0.93–4.9) in 2009.