Additional file 1: Table S1. SDAI (Simplified disease activity index) base line disease activity. Table S2. changes in SDAI and circulating biomarker concentrations following 6 months of synthetic DMARD therapy. Table S3. SDAI (Simplified disease activity index) response at 6 months. Table S4. SDAI (Simplified disease activity index) response at 6 months treatment sub-groups. Table S5. SDAI (Simplified disease activity index) response at 6 months risk allele sub-groups. ; BACKGROUND : To measure circulating anti-citrullinated peptide antibodies (ACPA) and cytokines pre- and 6 months post-therapy as a strategy to predict and optimize responses to traditional disease-modifying antirheumatic drugs (DMARDs) in early RA, which is an unmet need in developing countries. PATIENTS AND METHODS : A cohort of 140 predominantly (88.5 %) black female South African patients with early RA was treated with synthetic DMARDs, mostly methotrexate (MTX) alone, or in combination with low-dose oral corticosteroids (CS). Circulating ACPA and a panel of circulating cytokines/chemokines/growth factors were measured at baseline and after 6 months of therapy in relation to disease activity and Shared Epitope (SE). RESULTS : Following 6 months of therapy, the median simplified disease activity index (SDAI) declined from a baseline of 41.4 to 16.0 (p = 0.0001) for the entire cohort, which was paralleled by significant falls in median serum ACPA levels (516.6 vs. 255.7 units/ml, p =