Idiopathic inflammatory myopathies: definition and management of refractory disease.

Adult idiopathic inflammatory myopathies, commonly referred to as myositis, are a heterogeneous group of diseases with an autoimmune etiology. In this review, the authors are going to focus on myositis excluding inclusion body myositis. They will review the prognostic factors (for mortality and response to steroids), define refractory disease, introduce a new concept (presumed refractory disease), analyze definitions of active disease, damage and improvement criteria, and summarize therapeutic alternatives for refractory patients, based on different disease phenotypes.