Arthritis & Rheumatism, Volume 60,
October 2009 Abstract Supplement
The 2009 ACR/ARHP Annual Scientific Meeting
Philadelphia October 16-21, 2009.
Myopathy Independently Predicts Mortality in Scleroderma Patients
Valiyil, Ritu, Hummers, Laura K., Wigley, Fredrick M.
Skeletal muscle dysfunction and weakness, or myopathy, is prevalent in systemic sclerosis (SSc) and can be caused by numerous factors including malnutrition, disuse, medications, inflammatory myositis, or muscle fibrosis. We postulated that presence of myopathy of any cause during the course of disease associates with unique clinical features and outcomes.
We searched our cohort database that documents clinical and laboratory information prospectively collected every 6 months of all SSc patients seen at our specialty scleroderma center. Myopathy was defined if muscle weakness graded less than 5/5 by manual muscle strength testing and any one of the following characteristics was present: elevated muscle enzymes (CK or aldolase), abnormal muscle MRI, abnormal electromyography, or abnormal muscle biopsy. For each subject with myopathy, one SSc control without myopathy was selected by closest last visit and matched by age (± 5 yrs) and disease duration (± 3 mo). Demographic, disease activity, laboratory, pulmonary, and echocardiogram data were obtained from the database. Differences between SSc patients with and without myopathy were analyzed by chi-squared analysis or student's t test. Conditional multivariable logistic regression models were used to assess associations.
178 of 2,359 SSc patients met our criteria for myopathy and were matched to 178 patients without myopathy. Between the myopathy and non-myopathy groups, there were no statistical differences in mean age (55 yrs), disease duration (8.4 yrs), and sex (78% female vs. 85% respectively). When compared to controls, subjects with myopathy were more likely to be the diffuse skin subtype (66 vs. 37%, p<.001) and African-American (34 vs. 17%, p=0.001). Arthralgias were more frequent with myopathy (83 vs. 69%, p=0.003), as were tendon friction rubs (34 vs. 17%, p<.001) and synovitis (24 vs. 11%, p=0.001). SSc patients with myopathy were more likely to have lung disease with a lower mean % predicted FVC (59.3) than SSc patients without myopathy (73), p<.001, as well as cardiac dysfunction with a mean lower ejection fraction (54%) compared to controls (58%), p=0.004. Anti-RNP antibodies were strongly associated with myopathy (OR 5.5, CI 1.2224.8), while antibodies against centromere and topoisomerase I were negatively associated (OR 0.09, CI 0.020.39 and OR 0.29, CI 0.110.80 respectively). In adjusted multivariable analysis, a significant association was observed between myopathy and diffuse skin subtype (OR 2.7, CI 1.16.5) and % predicted FVC <= 60 (OR 3.27, CI 1.86.0). There was no association with smoking, cancer, FEV1/FVC ratio, and maximum RVSP. Increased mortality was associated with myopathy (OR 3.4, CI 1.38.9) and % FVC <= 60 (OR 14.5, CI 2.582). In subjects with % FVC >60, death was more frequent in subjects with myopathy (27 vs. 9%, p<.001).
Myopathy in scleroderma is significantly associated with diffuse skin subtype and lung disease and independently predicts mortality. Early recognition of muscle disease may identify scleroderma patients at high risk for poor outcomes and provide an opportunity for therapeutic intervention.
To cite this abstract, please use the following information:
Valiyil, Ritu, Hummers, Laura K., Wigley, Fredrick M.; Myopathy Independently Predicts Mortality in Scleroderma Patients [abstract]. Arthritis Rheum 2009;60 Suppl 10 :1737