Proximal weakness and creatine kinase elevation in systemic sclerosis: Clinical correlates, prognosis and functional...

Area of Science:

• Rheumatology
• Clinical Immunology
• Internal Medicine

Background:

• Systemic sclerosis (SSc) is a complex autoimmune disease characterized by fibrosis, vascular abnormalities, and immune system dysfunction.
• Muscle involvement, or myopathy, can occur in SSc, but its prevalence, clinical significance, and prognostic implications require further elucidation.

Purpose of the Study:

• To investigate the frequency of clinical evidence of muscle disease in SSc patients.
• To identify clinical correlates associated with muscle disease in SSc.
• To determine the prognostic implications of muscle disease in SSc.

Main Methods:

• Analysis of data from the Australian Scleroderma Cohort Study.
• Participants were categorized based on proximal weakness (PW) and elevated creatine kinase (CK) levels.
• Statistical analyses included chi-squared, ANOVA, Kruskal-Wallis tests, and Cox regression for survival analysis.

Main Results:

• Nearly half of the 1786 SSc participants exhibited clinical signs of muscle disease (PW and/or elevated CK).
• Concurrent PW and elevated CK were associated with a severe SSc phenotype, including diffuse cutaneous SSc, tendon friction rubs, synovitis, and digital ulcers.
• PW, with or without elevated CK, was linked to increased multimorbidity, cardiopulmonary disease, and significantly higher mortality rates.
• PW was also associated with impaired physical function, evidenced by reduced six-minute-walk-distance and higher HAQ-DI scores.

Conclusions:

• Clinical manifestations of myopathy are highly prevalent in systemic sclerosis.
• The presence of proximal weakness and/or elevated creatine kinase, even without definitive SSc-myopathy diagnosis, identifies patients with significant clinical associations and poorer prognosis.
• Early detection and management of muscle involvement in SSc are crucial for improving patient outcomes.