Personalized therapy in rheumatoid arthritis (PETRA): a protocol for a randomized controlled trial to test the effect of a psychological intervention in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disease that primarily affects cartilage and bone. Psychological stress can both trigger disease exacerbation and result from disease activity. As standard pharmacological interventions alone have limited success in treating RA, a more comprehensive biopsychosocial approach to treatment has been recommended.