From the Guidelines
Autoimmune myositis should be treated with high-dose corticosteroids, such as prednisone, starting at 0.5-1 mg/kg/day, in combination with immunosuppressants like methotrexate, azathioprine, or mycophenolate mofetil, as first-line therapy. This approach is based on the most recent and highest quality evidence available, including a study published in 2021 in the Annals of the Rheumatic Diseases 1. The treatment goals are to eliminate organ inflammation, prevent disease complications, reduce morbidity, and restore quality of life.
Key Treatment Considerations
- Corticosteroids, such as prednisone, are the cornerstone of treatment for autoimmune myositis, with a typical starting dose of 0.5-1 mg/kg/day 1.
- Immunossuppressants like methotrexate (15-25 mg weekly), azathioprine (1-2 mg/kg/day), or mycophenolate mofetil (1000-1500 mg twice daily) are often used in combination with corticosteroids to reduce the risk of relapse and improve treatment outcomes 1.
- For severe or refractory cases, intravenous immunoglobulin (IVIG) at 2 g/kg over 2-5 days or rituximab (two 1000 mg infusions separated by two weeks) may be considered as second-line therapy 1.
- Physical therapy is essential throughout treatment to maintain muscle strength and prevent contractures.
Monitoring and Evaluation
- Regular monitoring of muscle enzyme tests (CK, aldolase), muscle strength assessments, and evaluation for extramuscular manifestations like interstitial lung disease are crucial to assess treatment response and adjust therapy as needed 1.
- The main subtypes of autoimmune myositis, including dermatomyositis, polymyositis, immune-mediated necrotizing myopathy, and inclusion body myositis, each have distinct clinical features and treatment responses, and should be considered when developing a treatment plan 1.
From the Research
Autoimmune Myositis Treatment Options
- The treatment of autoimmune myositis, including dermatomyositis, polymyositis, and inclusion body myositis, typically involves the use of glucocorticoids as the mainstay of treatment 2.
- For patients who do not respond to glucocorticoids or experience relapses, add-on immunosuppressive therapy may be necessary, with options including azathioprine, methotrexate, and mycophenolate 3, 4.
- Intravenous immunoglobulin (IVIG) has been shown to be effective in some patients with dermatomyositis and polymyositis, and may be used as a second-line therapy 4, 5.
- Rituximab and tacrolimus may also be considered as additional treatment options for patients with autoimmune myositis 4.
- Pulse dose methylprednisolone therapy has been used in some cases of adult idiopathic inflammatory myopathy, with reported improvements in clinical and biochemical outcomes 6.
Disease-Specific Treatment Approaches
- Dermatomyositis and polymyositis are typically treated with oral high-dose prednisone combined with azathioprine or methotrexate to facilitate early tapering of prednisone 3.
- Inclusion body myositis (IBM) remains a challenging condition to treat, with some patients partially responding to steroids or IVIG, but often becoming unresponsive over time 4, 5.
- Immune-mediated necrotizing myopathy (IMNM) may be treated with IVIG, particularly in cases related to statin use 5.
- Myositis associated with antisynthetase syndrome (ASS) may require a combination of glucocorticoids and immunosuppressive therapy 5.