Therapeutic approaches in myositis

The inflammatory myopathies are a heterogeneous group of diseases including dermatomyositis, polymyositis, and inclusion body myositis. Few clinical trials have been conducted in myositis, making it difficult to provide clear recommendations on the treatment of these rare disorders. Although corticosteroids have not been tested in randomized controlled trials, the general expert consensus confirms their first-line use. However, in many patients, corticosteroid toxicity leads to significant disability, or these agents are ineffective, which then requires additional immunosuppression. Intravenous immunoglobulin is a reasonable short-term treatment with proven benefit in a controlled trial, but its long-term effectiveness remains unknown. The evidence for other immunosuppressive therapies has been derived mainly from case reports and open studies. These agents include methotrexate and/or azathioprine, followed by cyclosporine or tacrolimus (particularly for antisynthetase antibody-positive patients) and mycophenolate mofetil (for refractory rash). Newer therapies (eg, rituximab) are encouraging, but results from the largest randomized controlled trial studying this agent are soon to follow. The balance of evidence suggests that immunosuppressive drugs are effective in dermatomyositis and polymyositis, although randomized controlled trials are lacking.