Item selection for the development and validation of a revised classification criteria for adult and juvenile idiopathic inflammatory myopathies: MyoROC project

Objective: A revision of the 2017 EULAR-ACR myositis classification criteria, namely EULAR-ACR funded Myositis Revision of Classification (MyoROC) project, is currently underway involving a large international group of experts. In the first phase of this project, we identified additional items to be tested in the criteria. Methods: We distributed an electronic survey to International Myositis Assessment and Clinical Studies (IMACS) members to identify new items. The identified items were discussed within the Steering Committee and a multi-step Delphi consensus process consisting of an open discussion and three rounds of e-voting were conducted to reach the final item list. Results: The IMACS survey results revealed 24 new items. After an open discussion with Steering Committee members, 14 items were dropped and five new items were added, resulting in a total of 15 items. After three rounds of e-voting, the following variables were agreed to be tested in addition to the original items: finger flexion, knee extension ≥ hip flexion weakness, myonecrosis pattern on biopsy, magnetic resonance imaging and electromyography findings of myositis, additional rashes, skin biopsy, capillaroscopy, interstitial lung disease, arthritis, Raynaud's phenomenon, myositis-specific (MSA) and -associated autoantibodies, enzyme elevation at ≥2 time points, and aldolase. Conclusion: The new items that will be tested in the revised criteria were generated with input from a wide range of stakeholders and included, most importantly, MSA, pattern of weakness, skin changes, and additional diagnostic modalities. The next steps of the project are data collection followed by statistical analysis for development and validation of the revised criteria.