Efficacy of a Sequential Treatment Strategy in Rheumatoid Arthritis

Inclusion Criteria: * Aged between 18 or above * Rheumatoid arthritis according to ACR-EULAR 2010 (American College of Rheumatology-European League Against Rheumatism) * ACPA positive * Under methotrexate or leflunomide treatment for at least 3 months * DAS28-CRP\>3.2 under methotrexate or leflunomide calculated with CRP dated less than 7 days from baseline * Escape under synthetic background treatment defined by an elevation of C-reactive protein (CRP) (CRP\> 5mg/L ) or Erythrocyte sedimentation rate (ESR) (for men: \> age in years/2 ; for women: \> age (+10) /2)) within the last 6 months before baseline * Targeted DMARDs (biological and targeted synthetic DMARDs) naïve * Indication for a TNF inhibitor Exclusion Criteria: * Subject unable to read or/and write * Planned longer stay outside the region that prevents compliance with the visit plan * Subject unable to sign informed consent form * Subject not covered by public health insurance * Dementia * Fibromyalgia * Contra-indications to TNF inhibitor and/or Abatacept * Absence of tuberculosis screening in the previous 3 months before baseline * Patient with untreated active tuberculosis * Patient who cannot be followed during 48 weeks * Drug addiction, addiction to alcohol * Protected populations according to the French Public Health Code Articles L1121-5,6,8 (For example, pregnant, parturient or lactating women, prisoners, adults under guardianship or otherwise unable to consent). * Women of child bearing potential, unless they are using an effective method of birth control * Patient under law protection * Prisoners * Subject who are in a dependency or employment with the sponsor or the investigator * Participation in another interventional clinical trial or administration of an investigational product within the last 4 weeks before the screening date * Subject with moderate to severe heart failure (class 3 or class 4 cardiac disease as defined by the New York Heart Association Functional Classification) * Patients had a history of chronic obstructive pulmonary disease (COPD) and heavy smoking * Patients had a planned surgical procedure at least 30 days before the screening day * Known allergy or intolerance to an anti-TNF therapy * Hypersensitivity to the Abatacept or to any of its excipients * Patient with untreated active hepatitis B * Patient vaccinated with a live vaccine within 30 days prior to screening * Patients with an Inflammatory Bowel Disease (IBD) (loss of chance if switching from an anti-TNF to abatacept)