GSTM1 and anemia: AHF: acute heart failure, CHF: chronic heart failure, IDA: iron deficiency anemia, Hb: hemoglobin, AF: atrial fibrillation, CKD: chronic kidney disease, CAD: coronary artery disease, DM: diabetes mellitus, COPD: chronic obstructive pulmonary disease, NM: not mentioned, ID: iron deficiency