GSTM1 and chronic kidney disease: The prevalence of anemia (Hb ≤ 11 g/dL and Hb ≤ 10 g/dL) and possible CKD with decreased eGFR < 60 mL/min/1.73 m2 differed significantly by sex, age, and tested year (all p < 0.001, from a chi-square test).