Diagnostic measures for patients with systemic sclerosis-associated myopathy

Area of Science:

• Rheumatology
• Immunology
• Neurology

Background:

• Systemic sclerosis (SSc) is a connective tissue disease that can affect muscles, leading to SSc-associated myopathy (SSc-myopathy).
• Understanding the clinico-serological profile and diagnostic parameters of SSc-myopathy is crucial for effective patient management.

Purpose of the Study:

• To evaluate the clinico-serological profile of patients with SSc-myopathy.
• To assess the diagnostic accuracy of various parameters for identifying muscle involvement in SSc-myopathy.

Main Methods:

• Comparative analysis of SSc-myopathy patients against SSc patients without myopathy.
• Assessment of muscle performance using Manual Muscle Test for 8 muscle groups (MMT-8) and Functional Index-2 (FI-2).
• Comparison of muscle performance in SSc-myopathy patients with those suffering from primary myositis.

Main Results:

• SSc-myopathy patients more frequently exhibited immunosuppressive treatment, elevated creatine kinase (CK) levels, and anti-PM-Scl antibodies, with a lower prevalence of anti-RNA Polymerase III antibodies.
• Manual Muscle Test for 8 muscle groups (MMT-8) indicated mild muscle weakness in both SSc-myopathy and primary myositis patients.
• Functional Index-2 (FI-2) revealed compromised muscle endurance in both groups, but with differing patterns of affected muscle groups.

Conclusions:

• Previously identified clinic-serological characteristics of SSc-myopathy were confirmed.
• Autoantibody profiles and CK levels appear valuable for diagnosing SSc-myopathy.
• Functional muscle tests validated for primary myositis showed suboptimal performance in SSc-myopathy patients due to confounders and potential lack of sensitivity.