Rheumatoid Arthritis (RA) is a long-term disease that causes pain and swelling in the joints. This study compares two drugs, upadacitinib (a pill) and adalimumab (an injection), to see how well they help adults with RA who didn't improve with a previous treatment. The study involves about 480 participants around the world. Participants will either take upadacitinib daily with an injection placebo every other week or adalimumab injection every other week with a pill placebo daily. Neither participants nor doctors will know which treatment is given, ensuring fairness.

Participants will continue their assigned treatment for two periods and will be monitored for 30 and 70 days after. The study involves regular hospital or clinic visits to check side effects and treatment effectiveness through medical tests and questionnaires.

• The study requires regular hospital visits and monitoring.
• There are two treatment periods with follow-ups of 30 and 70 days.
• Participants must already be on a stable dose of the drug methotrexate.