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Response to: ‘External validation of EULAR/ACR classification criteria for idiopathic inflammatory myopathies’ by Luu et al
  1. Masatoshi Jinnin1,
  2. Akiko Ohta2,
  3. Hitoshi Kohsaka3
  1. 1Department of Dermatology, Wakayama Medical University, Wakayama, Wakayama, Japan
  2. 2Division of Public Health, Department of Social Medicine, Saitama Medical University, Moroyama, Saitama, Japan
  3. 3Rheumatology Center, Chiba-Nishi General Hospital, Chiba, Japan
  1. Correspondence to Dr Hitoshi Kohsaka, Rheumatology Center, Chiba-Nishi General Hospital, Chiba, 270-2251, Japan; kohsaka-mdr{at}

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We would like to thank Luu et al1 for their comments on our recent publication in the Annals of the Rheumatic Diseases, entitled ‘First external validation of sensitivity and specificity of the European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) classification criteria for idiopathic inflammatory myopathies with a Japanese cohort’.2

We are pleased to know similar validation studies of the new criteria3–7 have been carried out to strengthen our contention. Although Luu et al1 argue that earlier studies have been published before ours, they were not found with the PubMed search, using the name of the new criteria and validation as keywords, at the time of the submission of our manuscript in April 2019. Presumably, so did the reviewers of our manuscript. Before our publication, Luu et al gave their presentation in scientific meetings in 2018,3 4 which was followed by an official publication in the middle of 2019.5 It is common that presentations at scientific meetings precede the final and formal publication. The meeting abstracts do not appear in the literature databases, reflecting their possible scientific immaturity. In this regard, we gave oral presentations of our study at the meetings including the 13th International Workshop on Autoimmunity and Autoantibodies held in 2016. Nevertheless, we would like to point out that they made precious suggestion: inclusion of MRI or an extended antibody panel should improve the accuracy of the criteria.

A single-centre study reported by Hočevar et al6 was small in scale and retrospective but valuable. In a correspondence report, they raised the possibility of low sensitivity of the new criteria.

A larger retrospective report by Zhang et al,7 published in May 2019, also described that the new criteria showed high sensitivity and specificity. We agree with their suggestion that ‘other DM-associated rashes, such as technician’s hand, shawl sign and V area rash, may be included in the classification tree to improve the performance of the criteria in the future’.

Taken together, all of the above studies are greatly informative, suggesting overall high performance of the new criteria and possible difference in sensitivity and specificity among different ethnicities. They also show us what to be done in the future to improve the criteria.



  • Handling editor Josef S Smolen

  • Contributors Drafting of the manuscript: MJ, AO. Critical revision of the manuscript: HK.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Patient consent for publication Not required.

  • Provenance and peer review Commissioned; internally peer reviewed.

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