BSR Guideline on Idiopathic Inflammatory Myopathy Save

The British Society of Rheumatology (BSR) has published evidence-based guidelines for idiopathic inflammatory myopathy (IIM) affecting juvenile and adult-onset disease. This rare condition has an estimated prevalence of 5-15 per 100,000 persons.

The guideline committee that reviewed the literature and developed consensus using TAGREEII (Appraisal of Guidelines for Research and Evaluation II) methodology included 11 adult rheumatologists. 6 paediatric rheumatologists, 2 adult neurologists, a paediatric neurologist, nurse, pharmacist, dermatologists, paediatric dermatologist, 3 physiotherapists, and 4 patient representatives. 

A total of 213 papers were used to form recommendations.  The strength of recommendation was graded as strong = 1, or conditional = 2. Recommendation evidence was rated as  high (A), moderate (B), low (C) or very low (D), according to GRADE methodology. Thus each recommendation was scored by: Strength, Evidence and consensus (e.g. 1, B, 100%)

For full details on recommendations, please see the citation link at the end of this article. 

Highlight recommendations for specific clinical questions included:

How to Treat Skeletal Muscle Inflammation (myositis) ?

• High dose glucocorticoids (1, B, 100%).
  • Adult-specific: Oral prednisolone at a dose of 0.5–1 mg/kg/day, usually 40–60 mg daily (1, B, 100%)
  • Paediatric-specific: Oral prednisolone at a dose of 1–2 mg/kg/day or intravenous methylprednisolone pulses 30 mg/kg/day, maximum 1 g daily i.v. dose is recommended (1, B, 100%)
• DMARDS should be used to reduce muscle inflammation, achieve remission and reduce steroid burden (1, C, 100%)
• Adult-specific. Methotrexate, azathioprine, tacrolimus, ciclosporin, and mycophenolate mofetil are to be considered (2, C, 96%)
• Paediatric-specific. Early, complete control of muscle weakness and inflammation should be sought in juvenile-onset IIM, with the aim of improving outcomes and reducing disease-related complications (1, B, 100%).
  • A combination of high dose glucocorticoid and methotrexate should be used as first-line treatment in most cases (1, B, 100%)
  • Methotrexate is preferred over ciclosporin, as this has a more favourable side effect profile (1, B, 100%)
  • Mycophenolate mofetil may also be considered to improve skin and muscle disease (2, C, 100%)
• Intravenous immunoglobulin should be considered as a treatment of severe and/or refractory muscle inflammation (1, B, 100%)
• Refractory IIM - consider rituximab, cyclophosphamide or abatacept
• Exercise is safe and effective for people with IIM and can improve quality of life and function

How to Treat IIM-related Skin Manifestations ?

• Steroids and DMARDs as noted above are 1st line
• Refractory disease; Rituximab or IVIG 
• Sun avoidance and regular use of high factor broad spectrum sun cream

How to Manage IIM-related Interstitial Lung Disease (ILD) ?

• Paediatric-specific. Routinely assess PFTs/DLCO, as pulmonary function abnormalities may be asymptomatic (1, B, 100%)
• Adult-specific. Interstitial lung disease should be screened for in high-risk patients (1, B, 100%)
• In the treatment of rapidly progressive interstitial lung disease (RP-ILD):
  • Induction therapy with high dose steroids is to be considered (2, C, 96%)
  • Ciclosporin or tacrolimus, alongside steroids, to be considered in patients with RP-ILD (2, C, 96%)
  • Cyclophosphamide or rituximab therapy is to be considered early, potentially as part of the induction regimen (2, C, 96%)
• Adult-specific. In the treatment of chronic IIM-associated interstitial lung disease:
  • Immunosuppression using steroids with or without a single DMARD (azathioprine, ciclosporin, tacrolimus, mycophenolate) is to be considered (2, C, 100%).
  • Rituximab or cyclophosphamide is to be considered in treatment-resistant patients (2, C, 100%)

Who should have Cancer Screening with an IIM?

• Paediatric-specific. Routine screening for cancer is not warranted in juvenile-onset IIM (1, B, 100%)
• Adult-specific. The risk of cancer should be considered in all patients and screening should be particularly considered in those with the following risk factors (1, B, 100%):
  • Older age at onset
  • Male gender
  • Dysphagia
  • Cutaneous necrosis
  • Resistance to immunosuppressive therapy
  • Rapid disease onset
  • Positive anti-TIF1-γ autoantibodies
  • Positive anti-NXP2 autoantibodies
  • Negative for known myositis-specific abs

Other clinical questions covered in this guideline included:

• What management steps should be taken to reduce fracture risk in people with IIM?
• What key prognostic and management factors should be considered for children with IIM?
• Is autoantibody testing useful in people with IIM?
• How should IIM treatment during pregnancy and the breastfeeding period be amended?
• How should IIM-related cardiovascular disease be assessed for and treated?
• How should IIM-related dysphagia be screened for and managed?
• How should quality of life and mental wellbeing be assessed and treated in people with IIM?