What is the role of steroids (corticosteroids) in the treatment of Inclusion Body Myositis (IBM)?

Steroids in Inclusion Body Myositis (IBM)

Corticosteroids are not effective for the treatment of Inclusion Body Myositis (IBM) and are not recommended as they do not arrest or slow disease progression. 1

Evidence on Steroid Treatment in IBM

Inclusion Body Myositis is a distinct form of inflammatory myopathy that differs significantly from polymyositis in its response to treatment. While corticosteroids are first-line therapy for polymyositis 2, the evidence for IBM shows a different pattern:

• A Cochrane systematic review of treatment options for IBM found no effective treatment for reversing or minimizing disease progression, including corticosteroids 1
• Multiple studies have demonstrated that high-dose prednisone may actually worsen strength in IBM patients while decreasing inflammation but increasing amyloid accumulation 3
• In a study of 40 patients with IBM, prednisone treatment at doses typically effective for polymyositis failed to prevent disease progression in patients observed for 2 or more years 4

Clinical Characteristics of IBM

Understanding why steroids fail in IBM requires recognizing its unique features:

• Insidious onset, typically after age 50
• Progressive, indolent course with selective involvement of quadriceps, iliopsoas, tibialis anterior, biceps, and triceps muscles
• Male predominance (3:1 ratio)
• Normal or mildly elevated creatine kinase levels
• Distinctive pathological features including vacuoles containing membranous material and filamentous inclusions 4

Alternative Treatment Approaches

Given the ineffectiveness of steroids, other approaches have been investigated:

• Methotrexate has been studied but provided moderate-quality evidence of having no effect on IBM progression 1
• Interferon beta-1a similarly showed no important difference compared to placebo 1
• Some limited evidence suggests that combination therapy with anti-T lymphocyte immunoglobulin (ATG) combined with methotrexate may provide modest benefit 1
• In retrospective analyses, stabilization of disease (rather than improvement) appears to be an attainable goal in some patients with immunosuppressive therapies 5

Common Pitfalls in IBM Management

1. Misdiagnosis: IBM is frequently misdiagnosed initially (40% of cases in one study), leading to inappropriate treatment 6
2. Inappropriate steroid use: Continuing steroid therapy despite lack of response or worsening symptoms
3. Unrealistic expectations: Setting goals for improvement rather than stabilization of disease
4. Failure to recognize disease pattern: Not recognizing the characteristic pattern of muscle involvement that distinguishes IBM from other inflammatory myopathies

Clinical Approach

When evaluating a patient with suspected IBM:

1. Confirm diagnosis with muscle biopsy showing characteristic features (vacuoles, inflammatory exudate, and filamentous inclusions)
2. Avoid corticosteroid therapy as primary treatment
3. Consider clinical trials of novel agents or combination immunosuppressive therapies
4. Focus on supportive care and management of functional limitations
5. Monitor for associated conditions including other autoimmune disorders (15%), diabetes mellitus (20%), and peripheral neuropathy (18%) 4

The natural history of IBM includes stabilization or improvement in approximately one-third of patients for 6 months or more 3, which may explain some reports of apparent response to various therapies in small studies.