title: Long-term follow-up of 124 patients with polymyositis and dermatomyositis: Statistical analysis of prognostic factors.
abstract: OBJECTIVE
  The aims of this study were to clarify the long-term outcome of patients with polymyositis and dermatomyositis (PM/DM) and to elucidate prognostic factors using statistical analysis.
  
  
  METHODS
  We enrolled patients with PM/DM who visited our department between 1990 and 2014. Diagnoses of PM/DM and clinically amyopathic DM were based on the definitions of Bohan and Peter, and Sontheimer, respectively. We also obtained clinical data, such as age of onset, sex, medications, and presence of interstitial lung disease and malignancies, as well as laboratory tests, including the values of creatine kinase, KL-6, and ferritin. The follow-up was conducted until June 2014.
  
  
  RESULTS
  A total of 124 patients (PM: 46, DM: 78) were enrolled. The mean age of onset was 53.5 years, and females were predominant (64.5%). Overall survival rates were 93%, 86%, and 78% for 1, 5, and 10 years, respectively. The survival rates were significantly lower in patients with higher age of onset, with malignancies, and with hyperferritinemia in univariate analysis; however, multivariate analysis identified age of onset and serum ferritin as the most significant prognostic factors.
  
  
  CONCLUSIONS
  Our study indicates that when age of onset and serum ferritin are used in combination, we can predict prognosis of patients with PM/DM.
authors.affiliation: a Department of Hematology and Rheumatology , Tohoku University Graduate School of Medicine , Sendai , Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Ishizuka
authors.affiliation: a Department of Hematology and Rheumatology , Tohoku University Graduate School of Medicine , Sendai , Japan.
authors.forename: Ryu
authors.initials: R
authors.lastname: Watanabe
authors.affiliation: a Department of Hematology and Rheumatology , Tohoku University Graduate School of Medicine , Sendai , Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Ishii
authors.affiliation: a Department of Hematology and Rheumatology , Tohoku University Graduate School of Medicine , Sendai , Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Machiyama
authors.affiliation: a Department of Hematology and Rheumatology , Tohoku University Graduate School of Medicine , Sendai , Japan.
authors.forename: Kanae
authors.initials: K
authors.lastname: Akita
authors.affiliation: a Department of Hematology and Rheumatology , Tohoku University Graduate School of Medicine , Sendai , Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Fujita
authors.affiliation: a Department of Hematology and Rheumatology , Tohoku University Graduate School of Medicine , Sendai , Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Shirota
authors.affiliation: a Department of Hematology and Rheumatology , Tohoku University Graduate School of Medicine , Sendai , Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Fujii
authors.affiliation: a Department of Hematology and Rheumatology , Tohoku University Graduate School of Medicine , Sendai , Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Harigae
mesh_terms: D000328:Adult; D000368:Aged; D003402:Creatine Kinase / Q000097:blood; D003882:Dermatomyositis / Q000097:blood / Q000150:complications / Q000401:mortality*; D005260:Female; D005293:Ferritins / Q000097:blood; D005500:Follow-Up Studies; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000150:complications; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications; D017285:Polymyositis / Q000097:blood / Q000150:complications / Q000401:mortality*; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate
chemical_list: D005293:Ferritins; D003402:Creatine Kinase
keywords: Dermatomyositis; Long-term follow-up; Polymyositis; Prognostic factor