GSTM1 and anemia: Patient characteristics and laboratory parameters including C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), hemoglobin (Hb), hematocrit (Hct) and mean corpuscular volume (MCV), and values of NLR, PLR and SII were evaluated at baseline and after 12 months of continuous anti-TNF-α therapy.<h4>Results</h4>Anemia frequency dropped from 33.3% to 16.7% after one year of anti-TNF-α therapy.