title: Increased risk of venous thromboembolism in patients with dermatomyositis/polymyositis: a nationwide cohort study.
abstract: OBJECTIVE
  The number of previous studies on the risk of venous thromboembolism (VTE) in patients with dermatomyositis/polymyositis (DM/PM) is limited. Therefore, we conducted a nationwide retrospective cohort study to investigate the effects of DM/PM on the risk of VTE.
  
  
  METHODS
  We identified patients with newly diagnosed DM/PM in Taiwan between 2000 and 2010 using the National Health Insurance Research Database (NHIRD) and the Catastrophic Illness Patient Database. Each DM/PM patient was frequency-matched to 4 control patients according to age, sex, and index year. All of the patients were observed from the index date until the occurrence of a VTE event, censor, or until December 31, 2010. We calculated the hazard ratios (HRs) and 95% confidence intervals (CIs) of VTE in the DM/PM and comparison cohorts using the Cox proportional hazards regression model.
  
  
  RESULTS
  We followed up with the 2031 DM/PM patients (67.8% women, mean age of 46.1 y) and 8124 control patients for 9987 and 48 081 person-years, respectively. The DM/PM patients exhibited an 11.1-fold increased risk of VTE compared with that of the non-DM/PM comparison cohort after adjusting for age, sex, and comorbidities (95% CI=5.21-23.6). The older patients with DM/PM exhibited a multiplicative increased risk of VTE development compared with that of the control patients (adjusted HR=26.8, 95% CI=8.55-84.2), and the DM/PM patients with any comorbidity showed an additive risk of developing VTE (adjusted HR=33.3, 95% CI=11.2-99.4).
  
  
  CONCLUSIONS
  The risk of VTE is significantly higher in DM/PM patients than in non-DM/PM patients.
authors.affiliation: Department of Internal Medicine, Taichung Hospital, Ministry of Health and Welfare, Taichung, Taiwan; Department of Healthcare Administration, Central Taiwan University of Science and Technology, Taichung, Taiwan.
authors.forename: Wei-Sheng
authors.initials: WS
authors.lastname: Chung
authors.affiliation: Management Office for Health Data, China Medical University Hospital, Taichung, Taiwan.
authors.forename: Cheng-Li
authors.initials: CL
authors.lastname: Lin
authors.affiliation: Management Office for Health Data, China Medical University Hospital, Taichung, Taiwan; Graduate Institute of Clinical Medical Science and School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan. Electronic address: csung@mail.cmu.edu.tw.
authors.forename: Fung-Chang
authors.initials: FC
authors.lastname: Sung
authors.affiliation: Department of Internal Medicine, Taichung Hospital, Ministry of Health and Welfare, Taichung, Taiwan; Department of Healthcare Administration, Central Taiwan University of Science and Technology, Taichung, Taiwan.
authors.forename: Chuan-Chin
authors.initials: CC
authors.lastname: Lu
authors.affiliation: Graduate Institute of Clinical Medical Science and School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan; Department of Nuclear Medicine and PET Center, China Medical University Hospital, Taichung, Taiwan. Electronic address: d10040@mail.cmuh.org.tw.
authors.forename: Chia-Hung
authors.initials: CH
authors.lastname: Kao
mesh_terms: D000328:Adult; D000368:Aged; D016009:Chi-Square Distribution; D015897:Comorbidity; D016208:Databases, Factual; D003882:Dermatomyositis / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017285:Polymyositis / Q000175:diagnosis / Q000453:epidemiology*; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology; D013997:Time Factors; D054556:Venous Thromboembolism / Q000175:diagnosis / Q000453:epidemiology*
keywords: Dermatomyositis/polymyositis (DM/PM); National Health Insurance Research Database (NHIRD); Venous thromboembolism (VTE)