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2017 European League Against Rheumatism/American College of Rheumatology classification criteria for adult and juvenile idiopathic inflammatory myopathies and their major subgroups
  1. Ingrid E Lundberg1,
  2. Anna Tjärnlund1,
  3. Matteo Bottai2,
  4. Victoria P Werth3,
  5. Clarissa Pilkington4,
  6. Marianne de Visser5,
  7. Lars Alfredsson2,
  8. Anthony A Amato6,
  9. Richard J Barohn7,
  10. Matthew H Liang8,
  11. Jasvinder A Singh9,10,
  12. Rohit Aggarwal11,
  13. Snjolaug Arnardottir12,
  14. Hector Chinoy13,
  15. Robert G Cooper14,
  16. Katalin Dankó15,
  17. Mazen M Dimachkie7,
  18. Brian M Feldman16,
  19. Ignacio Garcia-De La Torre17,
  20. Patrick Gordon18,
  21. Taichi Hayashi19,
  22. James D Katz20,
  23. Hitoshi Kohsaka21,
  24. Peter A Lachenbruch22,
  25. Bianca A Lang23,
  26. Yuhui Li24,
  27. Chester V Oddis11,
  28. Marzena Olesinska25,
  29. Ann M Reed26,
  30. Lidia Rutkowska-Sak27,
  31. Helga Sanner28,
  32. Albert Selva-O’Callaghan29,
  33. Yeong-Wook Song30,
  34. Jiri Vencovsky31,
  35. Steven R Ytterberg32,
  36. Frederick W Miller33,
  37. Lisa G Rider33
  38. The International Myositis Classification Criteria Project consortium, The Euromyositis register and The Juvenile Dermatomyositis Cohort Biomarker Study and Repository (JDRG) (UK and Ireland)
  1. 1Rheumatology Unit, Department of Medicine, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden
  2. 2Institute for Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
  3. 3Department of Dermatology, Philadelphia VAMC and Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
  4. 4Department of Rheumatology, Great Ormond Street Hospital for Children NHS Trust, London, UK
  5. 5Department of Neurology, Academic Medical Centre, Amsterdam, The Netherlands
  6. 6Department of Neurology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
  7. 7Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA
  8. 8Division of Rheumatology, Immunology and Allergy, Brigham and Women’s Hospital, and Section of Rheumatology, Boston VA Healthcare, Boston, Massachusetts, USA
  9. 9Mayo Clinic College of Medicine, Rochester, Minnesota, USA
  10. 10University of Alabama and Birmingham VA Medical Center, Birmingham, USA
  11. 11Division of Rheumatology and Clinical Rheumatology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
  12. 12Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
  13. 13National Institute of Health Research Manchester Musculoskeletal Biomedical Research Unit, Central Manchester University Hospitals NHS Foundation Trust, University of Manchester, Manchester, UK
  14. 14MRC/ARUK Institute of Ageing and Chronic Disease, Faculty of Health & Life Sciences, University of Liverpool, Liverpool, UK
  15. 15Division of Immunology, 3rd Department of Internal Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
  16. 16Division of Rheumatology, Department of Pediatrics, University of Toronto and The Hospital for Sick Children, Toronto, Canada
  17. 17Department of Immunology and Rheumatology, Hospital General de Occidente, Secretaría de Salud, and University of Guadalajara, Guadalajara, Jalisco, Mexico
  18. 18Department of Rheumatology, King’s College Hospital NHS Foundation Trust, London, UK
  19. 19Clinical Immunology, Doctoral Program in Clinical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan
  20. 20National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA
  21. 21Department of Rheumatology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
  22. 22Department of Public Health, Oregon State University, Corvallis, Oregon, USA
  23. 23Division of Rheumatology, Department of Pediatrics, IWK Health Centre and Dalhousie University, Halifax, Canada
  24. 24Department of Rheumatology and Immunology, People’s Hospital of Beijing University, Beijing, China
  25. 25Connective Tissue Diseases Department, National Institute of Geriatrics, Rheumatology and Rehabilitation, Warsaw, Poland
  26. 26Department of Pediatrics, Duke University, Durham, North Carolina, USA
  27. 27Paediatric Clinic of Rheumatology, Institute of Rheumatology, Warsaw, Poland
  28. 28Section of Rheumatology, Oslo University Hospital–Rikshospitalet, Oslo, Norway
  29. 29Vall d’Hebron General Hospital, Barcelona, Spain
  30. 30Department of Internal Medicine, Medical Research Center, Clinical Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
  31. 31Department of Rheumatology, Institute of Rheumatology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic
  32. 32Division of Rheumatology, Mayo Clinic College of Medicine, Rochester, New York, USA
  33. 33US Department of Health and Human Services, Environmental Autoimmunity Group, Clinical Research Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Bethesda, Maryland, USA
  1. Correspondence to Ingrid E Lundberg, Rheumatology Unit, D2:01, Karolinska University Hospital, Solna, Stockholm S-171 76, Sweden; Ingrid.Lundberg{at}


Objective To develop and validate new classification criteria for adult and juvenile idiopathic inflammatory myopathies (IIM) and their major subgroups.

Methods Candidate variables were assembled from published criteria and expert opinion using consensus methodology. Data were collected from 47 rheumatology, dermatology, neurology and paediatric clinics worldwide. Several statistical methods were used to derive the classification criteria.

Results Based on data from 976 IIM patients (74% adults; 26% children) and 624 non-IIM patients with mimicking conditions (82% adults; 18% children), new criteria were derived. Each item is assigned a weighted score. The total score corresponds to a probability of having IIM. Subclassification is performed using a classification tree. A probability cut-off of 55%, corresponding to a score of 5.5 (6.7 with muscle biopsy) ‘probable IIM’, had best sensitivity/specificity (87%/82% without biopsies, 93%/88% with biopsies) and is recommended as a minimum to classify a patient as having IIM. A probability of ≥90%, corresponding to a score of ≥7.5 (≥8.7 with muscle biopsy), corresponds to ‘definite IIM’. A probability of <50%, corresponding to a score of <5.3 (<6.5 with muscle biopsy), rules out IIM, leaving a probability of ≥50 to <55% as ‘possible IIM’.

Conclusions The European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria for IIM have been endorsed by international rheumatology, dermatology, neurology and paediatric groups. They employ easily accessible and operationally defined elements, and have been partially validated. They allow classification of ‘definite’, ‘probable’ and ‘possible’ IIM, in addition to the major subgroups of IIM, including juvenile IIM. They generally perform better than existing criteria.

  • dermatomyositis
  • polymyositis
  • autoimmune diseases

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  • This article is published simultaneously in Arthritis & Rheumatology.

  • FWM and LGR contributed equally,

  • AT and MB contributed equally.

  • Handling editor Tore K Kvein

  • Contributors All authors were involved in drafting the article or revising it critically for important intellectual content and approved the final version to be published. All authors had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study conception and design: IEL, AT, MB, VPW, CP, MdV, LA, AAA, RJB, MHL, JAS, KD, BMF, HK, PAL, BAL, FWM, LGR. Acquisition of data: IEL, AT, MB, VPW, CP, MdV, LA, AAA, RJB, MHL, JAS, RA, SA, HC, RGC, KD, MMD, BMF, IG-DLT, PG, TH, JDK, HK, PAL, BAL, YL, CVO, MO, AMR, LR-S, HS, AS-O, YWS, JV, SRY, FWM, LGR, The International Myositis Classification Criteria Consortium, working committee members. Analysis and interpretation of data: IEL, AT, MB, VPW, CP, MdV, LA, AAA, RJB, MHL, JAS, RA, BMF, IG-DLT, PG, HK, PAL, BAL, YL, FWM, LGR.

  • Funding Financial support came from the European League Against Rheumatism (EULAR), American College of Rheumatology (ACR), The Myositis Association (TMA) and in part by the Intramural Research Program of the NIH, National Institute of Environmental Health Sciences and the European Science Foundation for the Euromyositis Register, the Swedish Research Council K2014-52X-14045-14-3 and through the regional agreement on medical training and clinical research (ALF) between Stockholm County Council and Karolinska Institutet. However, the project also received support (not financial support/funding) from different associations: the American Academy of Neurology (AAN), the Childhood Arthritis and Rheumatology Research Alliance (CARRA, CARRA Inc is funded by NIH-NIAMS), Friends of CARRA, and the Arthritis Foundation, the European Neuromuscular Centre (ENMC), the International Myositis Assessment and Clinical Studies Group (IMACS), the Muscle Study Group (MSG), the Rheumatologic Dermatology Society (RDS), the Pediatric RheumatologyEuropean Society (PReS) network for JDM and the Pediatric Rheumatology International Trials Organization (PRINTO).

  • Disclaimer The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of the Department of Veterans Affairs or the United States government, or the NHS, the National Institute for Health Research or the Department of Health (UK).

  • Competing interests JAS has received research grants from Takeda and Savient and consultant fees from Savient, Takeda, Regeneron, Merz, Iroko, Bioiberica, Crealta and Allergan. JAS serves as the principal investigator for an investigator-initiated study funded by Horizon pharmaceuticals through a grant to DINORA, Inc., a 501 (c)(3) entity. JAS is a member of the executive committee of OMERACT, an organisation that develops outcome measures in rheumatology and receives arms-length funding from 36 companies; a member of the American College of Rheumatology’s (ACR) Annual Meeting Planning Committee (AMPC); Chair of the ACR Meet-the-Professor, Workshop and Study Group Subcommittee; and a member of the Veterans Affairs Rheumatology Field Advisory Committee. HC and RGC’s work in myositis is partly funded by grants from Arthritis Research UK (18474) and the Medical Research Council (MR/N003322/1). JV’s work in myositis is supported by Project (Ministry of Health, Czech Republic) for conceptual development of research organization 00023728.

  • Ethics approval Ethical committees at each participating centre.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Collaborators The collaborators are included in the appendix.

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