GSTM1 and chronic kidney disease: Groups 2 (“lower and growing slightly”) (Hb 110–120 g/L, HCT approximately 35%), 3 (“higher and growing slightly”) (Hb 125–135 g/L, HCT approximately 40%), and 4 (“higher and growing steadily”) (Hb 145–160 g/L, HCT approximately 45%) served as independent protective factors for patients with CKD stages 3–4 for the composite outcome (p=0.000; p for trend<0.000).