The British Society for Rheumatology (BSR) released evidence-based guidelines for the management of idiopathic inflammatory myopathy (IIM) among pediatric and adult patients. The full report was published in Rheumatology.

The authors noted that this is the first set of evidence-based guidelines developed for IIM that affects both adults and children.

Guideline development followed the BSR Creating Clinical Guidelines Protocol using appraisal of guidelines for research and evaluation II (AGREEII) methodology. The working group identified key questions, which formed the basis for literature searches of peer-reviewed clinical studies and case reports. The group then reviewed eligible studies and drafted recommendations. The quality of evidence for each recommendation was graded as high, moderate, low, or very low. The wording and strength of each draft recommendation was finalized through a consensus building process.


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In total, 13 key questions were identified. Recommendations (strength of recommendation, quality of evidence, and strength of workgroup agreement) for each of these categories were highlighted.

1. Treating Skeletal Muscle Inflammation

  • High-dose glucocorticoids are recommended to treat muscle inflammation at the time of treatment induction.
  • Taper oral prednisolone may be used, according to clinical response, approximately 6 weeks after initiating treatment.
  • An exercise regimen, led by a physiotherapist or occupational therapist, can be considered as part of IIM management to improve quality of life and function.

Disease-modifying antirheumatic drugs (DMARDs) can help reduce muscle inflammation, achieve clinical remission, and reduce steroid burden.

Specific recommendations for DMARD use were included in the report.

  • Among children: Early, complete control of muscle weakness and inflammation to improve outcomes and reduce disease-related complications. Use of glucocorticoids and methotrexate as first-line treatment in most cases, with a combination of prednisolone and methotrexate preferred to prednisolone plus ciclosporin to reduce side effects. Treatment with mycophenolate mofetil to improve skin and muscle disease.
  • Among adults: Methotrexate, azathioprine, tacrolimus, ciclosporin, and mycophenolate mofetil for the treatment of active myositis and long-term maintenance of disease remission.

Potential second-line treatment options were noted.

  • Intravenous immunoglobulin (IVIG) for severe and/or refractory muscle inflammation.
  • Rituximab for patients with refractory myositis (especially in children) with a positive myositis autoantibody profile and those with a lower burden of disease damage.
  • Cyclophosphamide for severe and/or refractory IIM.
  • Abatacept for refractory adult IIM.

2. Treating IIM-Related Skin Manifestations

  • Among patients with skin disease refractory to glucocorticoid/conventional synthetic DMARD-based immunosuppression, treatment options can include rituximab and IVIG.
  • Patients must be advised to avoid sun exposure or use a high-factor, broad-spectrum sunscreen to reduce the risk for cutaneous and noncutaneous disease flares.
  • Children with active skin manifestations may receive systemic immunosuppressive drugs, especially in the presence of nailfold capillary abnormalities. The working group also recommended early treatment to improve remission and reduce calcification development.

3. Screening and Managing IIM-related Interstitial Lung Disease (ILD)

Screening Recommendations

  • Because pulmonary function abnormalities are common in children with IIM and may be asymptomatic, pulmonary function should be assessed routinely.
  • High-risk adults should be screened for ILD.

Treatment Recommendations

Patients with ILD should also be referred to a respiratory specialist. Treatment options for adults with rapidly progressive ILD were as follows:

  • Induction therapy with high-dose steroids
  • Ciclosporin or tacrolimus in conjunction with steroids.
  • Cyclophosphamide or rituximab as part of induction therapy.

For adults with chronic IIM-associated ILD, the working group noted the following treatment options:

  • Immunosuppression using steroids with or without a single DMARD
  • Rituximab or cyclophosphamide for treatment-resistant patients

4. Reducing Fracture Risk in Adult Patients With IIM

  • Assessing fracture risk is important in adults with IIM, in light of glucocorticoid use, female preponderance, and older age of onset. A bone health assessment should be conducted at diagnosis and whenever risk factors change.

5. Key Prognostic and Management Factors for Pediatric Patients With IIM

  • Juvenile-onset IIM differs from adult-onset IIM and should be managed by a pediatric specialist.
  • Timely diagnosis and treatment are associated with improved disease outcomes. Early referral to a specialist can be considered.
  • Clinicians should use age-appropriate tools, such as the Childhood Myositis Assessment Score, Childhood Health Assessment Questionnaire, and Juvenile Dermatomyositis Multidimensional Assessment Report, to assess muscle strength, function and quality of life.
  • Children must be screened for overlapping connective tissue disease, which is associated with increased mortality.
  • Children must also be assessed for the presence of calcinosis using clinical examination and plain x-ray radiography.

6. Use of Autoantibody Testing in Patients With IIM

  • Myositis autoantibody testing is recommended for its role in facilitating diagnosis, informing disease phenotype and prognosis, and helping tailor treatment.

7. Cancer Screening in Patients With IIM

  • Juvenile-onset IIM is not associated with cancer; therefore, screening children with IIM may not be necessary.
  • Cancer screening can be considered for adults with IIM, especially those with risk factors such as older age at onset, male gender, dysphagia, cutaneous necrosis, immunosuppressive therapy resistance, rapid disease onset, positive anti-TIF1-g or anti-NXP2 autoantibodies, and those who test negative for known myositis-specific autoantibodies.

8. Treating Pregnant and Breastfeeding Women

Research has shown higher risk for low birth weight, obstetric complications, and longer hospitalization in women with IIM.

  • Women with IIM should be advised to conceive when their disease is well controlled.
  • Patients with IIM should be managed in conjunction with a maternal medicine specialist.
  • Clinician must be vigilant during the postpartum period for occurrence of disease flares.

9. Assessing and Treating IIM-Related Cardiovascular Disease

  • Adult patients with IIM should be routinely assessed for cardiovascular risk.
  • Cardiovascular risk factors must be assessed among children with IIM (hypertension, obesity, and metabolic abnormalities) and managed appropriately.

10. Screening for Cardiac Involvement in IIM

  • All adult patients with IIM must be screened for cardiac involvement. Diagnostic tests can include serum cardiac damage marker testing, electrocardiography, echocardiography, and cardiac magnetic resonance imaging (MRI). Cardiac troponin 1 may be recommended over cardiac troponin T.
  • Clinicians can considered screening children with IIM for cardiac involvement using electrocardiography and echocardiography.

11. Assessing and Managing IIM-Related Dysphagia

Dysphagia is common among patients with IIM, affecting their quality of life and increasing the risk for weight loss and aspiration pneumonia.

  • Clinicians must routinely assess patients for dysphagia.
  • Early involvement of speech and language therapists for patients with dysphagia can be considered.
  • Among patients with active disease and dysphagia with resistance to other treatments, IVIG can be recommended.

12. Assessing and Treating Quality of Life and Mental Well-Being

  • All patients must be assessed for psychologic well-being and psychiatric comorbidities.
  • Age-appropriate assessment tools, such as the Child Health Questionnaire (CHQ-50) and the adult-specific 36-item Short Form survey, can be used.
  • Factors that negatively impact health-related quality of life, such as skin involvement, pruritis, and steroid adverse effects, must be addressed.
  • Factors that impact quality of life among pediatric patients, such as pain, muscle weakness, and poor sleep, should be managed appropriately.
  • Patients with IIM must be encouraged to participate in individually tailored exercises and rehabilitation across all ranges of disease activity to improve mental well-being.
  • Physiotherapy or occupational therapy may also be considered to improve poor grip strength, which can impact activities of daily living and quality of life.

13. Management Considerations for Certain Ethnic Groups

  • Clinical symptoms, associated autoantibodies, and underlying risk factors vary by ethnicity. Clinicians should consider these differences when assessing patients with IIM.

Reference

Oldroyd AGS, Lilleker JB, Amin T, et al.; for the British Society for Rheumatology Standards, Audit and Guidelines Working Group. British Society for Rheumatology guideline on management of paediatric, adolescent and adult patients with idiopathic inflammatory myopathy. Rheumatology. Published on March 31, 2022. doi:10.1093/rheumatology/keac115