People with the scleroderma experience a thickening of the skin and other tissues in the body. A study from the Division of Rheumatology led by Julie J. Paik MD, MHS, Laura K. Hummers MD, ScM, and Andrew L. Mammen, MD, PhD found that some patients experience muscle weakness due to an accumulation of fibrous tissue in their muscles without signs of inflammation, called “fibrosing myopathy”. Fibrosing myopathy was associated with a worse clinical outcome including increased death from cardiac disease, stressing the need to further monitor scleroderma patients with this finding.
Why was this study done?
Although it was known that a large portion of people with scleroderma experience muscle weakness, the causes of weakness and associated long term outcomes have not been completely studied. For this study, the researchers wanted to determine if unique subtypes of scleroderma muscle disease existed among different patients. They also wanted to understand if this information, obtained through a muscle biopsy, was associated with other physical features of the disease, laboratory findings, and long-term outcomes.
How was this study done?
This study was completed by reviewing medical charts, laboratory data, blood specimens, and muscle biopsies from over 1500 patients seen at the Johns Hopkins Scleroderma Center between 1990 and 2014. Almost 25% of patients seen by the center during this period experienced muscle weakness. From this group, the researchers studied muscle biopsies from 37 people with scleroderma who had obvious signs of muscle weakness. Eight people whose biopsies showed an accumulation of fibrous tissue in the muscle without inflammation were considered to have “fibrosing myopathy”. Muscle biopsies from the other 29 peopled showed signs of inflammation so were considered to have “inflammatory myopathy”. Data including physical features of scleroderma, laboratory findings, and long-term survival were compared between these two distinct groups of patients.
What were the major findings?
People with scleroderma who had fibrosing myopathy were more likely to have widespread thickening of the skin over many areas of the body, be of African-American race, and have lower “forced vital capacity” (indicating impaired lung function), compared to people with inflammatory myopathy. They also had lower levels of muscle enzymes, indicating less ongoing damage to the muscle. However, people with fibrosing myopathy had a significantly higher mortality (5 of 8 with fibrosing myopathy; 62.5% compared to 4 of 29 with inflammatory myopathy (14.3%). The cause of death in 60% of these patients was due to cardiac disease.
What is the impact of this work?
Fibrosing myopathy is a unique subtype of muscle disease that can be observed in people with scleroderma. It is associated with a higher risk of mortality, especially due to cardiac disease. This underscores the importance of learning more about this unique muscle finding to identify how best to monitor and treat this group of scleroderma patients at risk for severe disease outcomes.
This research was supported by:
The Johns Hopkins Rheumatic Disease Research Core Center, Donald B. and Dorothy L. Stabler Foundation, Doris Duke Early Clinician Investigator Award, John Staurulakis Endowed Scholar Award, Chresanthe Stauralakis Memorial Discovery Fund, Scleroderma Research Foundation and McCrory Professorship, and in part, by the Intramural Research Program of the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health (K23 AR-061439, P30-AR053503).
Link to original research article:
Fibrosing myopathy in systemic sclerosis associates with higher mortality. Paik JJ, Wigley FM, Shah AA, Corse AM, Casciola-Rosen L, Hummers LK, Mammen AL. Arthritis Care Res (Hoboken). 2017 May 23. doi: 10.1002/acr.23291. [Epub ahead of print]