Age-stratified models also showed that older children within each strata has significantly lower odds of anemia compared to younger children, except among children 5–7 years old, which further showed that males had higher risk of anemia and lower hemoglobin levels than females (OR = 1.49, 95% CI 1.01–2.21; Hb = –0.18, 95% CI –0.38–0.02). This evidence concerns the gene GSTM1 and anemia.