GSTM1 and anemia (phenotype): CBIs also significantly reduced the mean STH intensity (SMD: −3.16, 95 CI: −4.28, −2.04).Twelve studies reported on the hemoglobin (Hb) levels and showed significantly improved mean Hb in the intervention group (SMD: 0.34, 95% CI: 0.20, 0.47), while anemia significantly reduced by 10% (RR: 0.90, 95% CI: 0.85, 0.96) (see Figures 4 and 5).