1Department of Internal Medicine 3, Friedrich-Alexander-University Erlangen-Nürnberg and Universitätsklinikum Erlangen, Erlangen, Germany
2Deutsches Zentrum Immuntherapie (DZI), Friedrich-Alexander-University, Erlangen, Germany
3III. Department of Internal Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
4Faculty of Health Sciences, Center for Health Services Research, Brandenburg Medical School Theodor Fontane, Rüdersdorf, Germany
5Praxis für Rheumatologie, Klinische Immunologie, Medical Center, Baden-Baden, Germany
6Faculty of Health Sciences Brandenburg, Brandenburg Medical School Theodor Fontane, Rüdersdorf bei Berlin, Germany
7Department of Neurology and Pain Treatment, Center for Translational Medicine, Neuromuscular Center, Immanuel Klinik Rüdersdorf, University Hospital of the Brandenburg Medical School Theodor Fontane, Rüdersdorf bei Berlin, Germany
8Department of Neurology, Neuromuscular Center, University Medical Center, Göttingen, Germany
9Myositis-Gruppe, Deutsche Gesellschaft Für Muskelkranke, Freiburg, Germany
10The Swedish Working Group for Myositis, The Swedish Rheumatism Association, Stockholm, Sweden
11Department of Rheumatology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
12Department of Rheumatology, Royal Wolverhampton Hospitals NHS Trust, Wolverhampton, UK
13Division of Musculoskeletal and Dermatological Sciences, School of Biological Sciences, Centre for Musculoskeletal Research, The University of Manchester, Manchester, UK
14Department of Rheumatology, City Hospital, Sandwell and West Birmingham Hospitals NHS Trust, Birmingham, UK
15Department of Rheumatology, Salford Royal Hospital, Northern Care Alliance NHS Foundation Trust, Manchester Academic Health Science Centre, Salford, UK
16Division of Musculoskeletal and Dermatological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
17Division of Rheumatology, Department of Medicine, Karolinska Institutet, Karolinska University Hospital, Solna, Sweden
18Department of Gastroenterology, Dermatology and Rheumatology, Karolinska University Hospital, Stockholm, Sweden
19Rheumatology Division, Fondazione Istituti di Ricovero e Cura a Carattere Scientifico (IRCCS) Policlinico San Matteo, Pavia, Italy