A Study to Determine the Effect of Methotrexate (MTX) Dose on Clinical Outcome and Ultrasonographic Signs in Subjects With Moderately to Severely Active Rheumatoid Arthritis (RA) Treated With Adalimumab (MUSICA)

* Adult subjects with moderately to severely active rheumatoid arthritis * Subjects must have a DAS28(CRP) (Disease Activity Score using C-Reactive Protein) greater than or equal to 3.2 at baseline (there is no minimum CRP score required to qualify) * Subjects must have at least 5/68 tender joints plus 5/66 swollen joints assessed at screening or baseline * Subject must treated with and MTX (methotrexate) dose (oral and/or injectable) of 15 mg or more per week (no upper limit on dose) for at least 12 weeks prior to screening * Subject is either biologic-naïve or has only one prior biologic disease-modifying antirheumatic drug (i.e. abatacept, anakinra, certolizumab, etanercept, golimumab, infliximab, or tocilizumab)

* Previous exposure to adalimumab (Humira), rituximab (Rituxan), natalizumab (Tysabri), efalizumab (Raptiva) * Subject has been treated with intra-articular or parenteral administration of corticosteroids within 4 weeks of screening * Subject has diagnosis or history of gout or pseudogout * Subject has undergone joint surgery within 12 weeks of screening (at joints to be assessed by ultrasound) * Subject has history of chronic arthritis diagnosed before age 16 years