title: Disease activity and prognostic factors in juvenile dermatomyositis: a long-term follow-up study applying the Paediatric Rheumatology International Trials Organization criteria for inactive disease and the myositis disease activity assessment tool.
abstract: OBJECTIVE
  The aims of this study were to examine disease activity by the Paediatric Rheumatology International Trials Organization (PRINTO) criteria for inactive disease and the Myositis Disease Activity Assessment Tool (MDAAT) in JDM patients after long-term follow-up and to identify predictors of these outcomes.
  
  
  METHODS
  A retrospective inception cohort of 59 patients diagnosed with JDM was clinically examined in a cross-sectional study a median of 16.8 years (range 2.0-38.1) after symptom onset. Patients were divided by the PRINTO criteria into clinically inactive and active disease. Disease activity was also measured by MDAAT and other validated tools. Medical records were reviewed for early disease variables and medication.
  
  
  RESULTS
  By the PRINTO criteria, 31/59 (51%) patients were active and 29/59 (49%) were inactive. By MDAAT, 43/59 (73%) of the patients had measurable disease activity, most commonly found in the skin (59%) and skeletal (27%) systems. MDAAT showed moderate to strong correlations with other disease activity measures (rsp 0.39-0.87, P < 0.05) except for muscle enzymes. Active patients had higher disease activity than inactive patients measured by MDAAT (P < 0.001) and other disease characteristics (all P ≤ 0.002) except for patients' global assessment of disease activity. After controlling for gender and follow-up time, calcinosis during disease-course predicted high MDAAT, age<9 years at diagnosis predicted active disease and organ damage present 6-12 months post diagnosis predicted both outcomes.
  
  
  CONCLUSIONS
  After 16.8 years, 51-73% of JDM patients had active disease. Disease activity by the PRINTO criteria and MDAAT were moderately to highly associated with most other disease characteristics and was predicted by early damage.
authors.affiliation: Section of Rheumatology, Norwegian Competence Center of Pediatric and Adolescent Rheumatology, Oslo University Hospital-Rikshospitalet, Institute for Experimental Medical Research, Department of Cardiology, Oslo University Hospital-Ullevål and Institute for Clinical Medicine, Medical Faculty, University of Oslo, Norway.Section of Rheumatology, Norwegian Competence Center of Pediatric and Adolescent Rheumatology, Oslo University Hospital-Rikshospitalet, Institute for Experimental Medical Research, Department of Cardiology, Oslo University Hospital-Ullevål and Institute for Clinical Medicine, Medical Faculty, University of Oslo, Norway. helga.sanner@medisin.uio.no.
authors.forename: Helga
authors.initials: H
authors.lastname: Sanner
authors.affiliation: Section of Rheumatology, Norwegian Competence Center of Pediatric and Adolescent Rheumatology, Oslo University Hospital-Rikshospitalet, Institute for Experimental Medical Research, Department of Cardiology, Oslo University Hospital-Ullevål and Institute for Clinical Medicine, Medical Faculty, University of Oslo, Norway.Section of Rheumatology, Norwegian Competence Center of Pediatric and Adolescent Rheumatology, Oslo University Hospital-Rikshospitalet, Institute for Experimental Medical Research, Department of Cardiology, Oslo University Hospital-Ullevål and Institute for Clinical Medicine, Medical Faculty, University of Oslo, Norway.Section of Rheumatology, Norwegian Competence Center of Pediatric and Adolescent Rheumatology, Oslo University Hospital-Rikshospitalet, Institute for Experimental Medical Research, Department of Cardiology, Oslo University Hospital-Ullevål and Institute for Clinical Medicine, Medical Faculty, University of Oslo, Norway.
authors.forename: Ivar
authors.initials: I
authors.lastname: Sjaastad
authors.affiliation: Section of Rheumatology, Norwegian Competence Center of Pediatric and Adolescent Rheumatology, Oslo University Hospital-Rikshospitalet, Institute for Experimental Medical Research, Department of Cardiology, Oslo University Hospital-Ullevål and Institute for Clinical Medicine, Medical Faculty, University of Oslo, Norway.Section of Rheumatology, Norwegian Competence Center of Pediatric and Adolescent Rheumatology, Oslo University Hospital-Rikshospitalet, Institute for Experimental Medical Research, Department of Cardiology, Oslo University Hospital-Ullevål and Institute for Clinical Medicine, Medical Faculty, University of Oslo, Norway.
authors.forename: Berit
authors.initials: B
authors.lastname: Flatø
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D018501:Antirheumatic Agents / Q000627:therapeutic use; D002114:Calcinosis / Q000209:etiology; D002648:Child; D002675:Child, Preschool; D003882:Dermatomyositis / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011379:Prognosis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D055815:Young Adult
chemical_list: D018501:Antirheumatic Agents
keywords: adolescent rheumatology; dermatomyositis; disease activity; myositis; outcome measures; outcomes research; paediatric rheumatology