Idiopathic inflammatory myopathies (IIM) are rare inflammatory autoimmune diseases, commonly with primary involvement of the skeletal muscle. IIM are multi-system diseases often extending beyond muscle weakness and may involve the lungs, joints, skin, and the gastrointestinal tract.

The aim of the Outcome Measures in Rheumatology (OMERACT) Myositis group is to identify core domains and instruments that reflect the life impact area in IIM, with strong patient participation.