title: Myopathy is a poor prognostic feature in systemic sclerosis: results from the Canadian Scleroderma Research Group (CSRG) cohort.
abstract: OBJECTIVE
  To determine the clinical impact of muscle involvement in a large systemic sclerosis (SSc) cohort.
  
  
  METHODS
  Using the Canadian Scleroderma Research Group (CSRG) database, SSc patients with either elevated creatine kinase (CK) or a prior history of myositis/myopathy were identified. Regression and Kaplan-Meier analyses were performed to determine characteristics associated with muscle involvement in SSc and survival outcome.
  
  
  RESULTS
  In 1145 patients with SSc, 5.6% had an elevated CK. This subset was more likely to be male (24.5% in elevated CK vs. 12.6% in normal CK, p < 0.013), younger (52 vs. 56 years, p < 0.045), have diffuse cutaneous SSc (dcSSc; 40.4% vs. 37.9%, p < 0.002), tendon friction rubs (30.0% vs. 13.4%, p < 0.001), and forced vital capacity (FVC) < 70% (23.9% vs. 13.1%, p < 0.039), be ribonucleoprotein (RNP) antibody positive (12.0% vs. 5.0%, p < 0.032), topoisomerase1 (topo1)-antibody positive (26.0% vs. 14.4%, p < 0.026), have a higher modified Rodnan skin score (MRSS; 16.14 vs. 9.81, p < 0.001), and a higher Health Assessment Questionnaire (HAQ) score (0.98 vs. 0.79, p < 0.011). Survival was reduced for patients with elevated CK (p < 0.025). Nearly 10% of patients in the CSRG cohort had a prior history of myositis/myopathy. This subset also had findings similar to those with elevated CK and increased mortality (p < 0.003).
  
  
  CONCLUSIONS
  Muscle involvement in SSc has a poor prognosis impacting survival, especially in men with early dcSSc with topo1 and RNP autoantibodies and interstitial lung disease (ILD).
authors.affiliation: University of Western Ontario, Schulich School of Medicine and Dentistry, Department of Medicine, Division of Rheumatology, St Joseph's Health Care , London, ON , Canada.
authors.forename: M
authors.initials: M
authors.lastname: Jung
authors.forename: A
authors.initials: A
authors.lastname: Bonner
authors.forename: M
authors.initials: M
authors.lastname: Hudson
authors.forename: M
authors.initials: M
authors.lastname: Baron
authors.forename: J E
authors.initials: JE
authors.lastname: Pope
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D002170:Canada / Q000453:epidemiology; D002423:Cause of Death; D015331:Cohort Studies; D015897:Comorbidity; D003402:Creatine Kinase / Q000378:metabolism*; D016208:Databases, Factual; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D017563:Lung Diseases, Interstitial / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009135:Muscular Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D012595:Scleroderma, Systemic / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D012720:Severity of Illness Index; D017678:Sex Distribution; D018709:Statistics, Nonparametric; D016019:Survival Analysis
chemical_list: D003402:Creatine Kinase