Background:Concomitant use of methotrexate (MTX) in abatacept (ABA) therapy is associated with good clinical response in patients with rheumatoid arthritis (RA) who are naïve to biological disease-modifying antirheumatic drugs (bDMARDs)1,2. However, it is unclear when abatacept is used in patients with prior bDMARDs use3.Objectives:We compared the effectiveness of abatacept monotherapy versus abatacept combined with methotrexate therapy in rheumatoid arthritis patients with prior bDMARDs use.Methods:Retrospective cohorts study. Rheumatoid arthritis patients treated with abatacept between 2009 and 2019 (n=86). Socio-demographic, clinical and pharmacological characteristics of patients were collected. We compared clinical effectiveness between ABA monotherapy patients (n=49) and abatacept concomitant methotrexate therapy patients (n=37), prior treated with bDMARDs. The effectiveness was measured according toThe European League Against Rheumatism(EULAR) response withDisease Activity Score(DAS28) like satisfactory (DAS28<3.2) or unsatisfactory (DAS28≥3.2), after 12 months of ABA therapy in RA patients.Results:49 RA patients have been evaluated in ABA monotherapy group; 83.67% (41/49) were women, disease duration was 16 (10-22) years and age of RA diagnosis was 48 (38.25-57.00). Concomitants glucocorticoids were administrated in 81.63% (40/49). Rheumatoid factor (RF) was positive in 75.51% (37/49) patients and cyclic citrullinated peptide antibodies (ACPA) in 71.43% (35/49). At 12 months, 40.82% (20/49) of patients had satisfactory EULAR response.In the combination therapy group, the age of RA diagnosis was 42.5 (35.75-53.50), 75.68% (28/37) were women and the disease duration was 12 (7-21) years. 89.19% (33/37) had concomitants glucocorticoids and the RF was positive in 72.97% (27/37) of patients. EULAR response was satisfactory at 12 months in 43.24% (16/37) of patients. No difference in treatment effectiveness was found in patients receiving abatacept in combination therapy with MTX compared with ABA monotherapy (p=0.829; IC95=0.35-2.35).Conclusion:Abatacept plus methotrexate therapy did not improve the effectiveness in rheumatoid arthritis patients with prior bDMARDs use, compared with abatacept monotherapy.References:[1]Genovese M, Schiff M, Luggen M, Becker J, Aranda R, Teng J, et al. Efficacy and safety of the selective co-stimulation modulator abatacept following 2 years of treatment in patients with rheumatoid arthritis and an inadequate response to anti-tumour necrosis factor therapy. Annals of the rheumatic diseases. 2008;67(4):547-54.[2]Smolen JS, Landewe RBM, Bijlsma JWJ, Burmester GR, Dougados M, Kerschbaumer A, et al. EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs: 2019 update. Ann Rheum Dis. 2020.[3]Walker UA, Jaeger VK, Chatzidionysiou K, Hetland ML, Hauge E-M, Pavelka K, et al. Rituximab done: what’s next in rheumatoid arthritis? A European observational longitudinal study assessing the effectiveness of biologics after rituximab treatment in rheumatoid arthritis. Rheumatology. 2016;55(2):230-6Disclosure of Interests:None declared