The Assessment of SpondyloArthritis International Society (ASAS) Consensus-Based Expert Definition of Difficult-to-Manage, including Treatment-Refractory, Axial Spondyloarthritis.

Address: Division of Rheumatology, Department of Medicine, University of Toronto and University Health Network, Toronto, ON, Canada; Department of Gastroenterology, Infectiology and Rheumatology (including Nutrition Medicine), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany. Electronic address: [email protected].; Department of Rheumatology, La Paz University Hospital, IdiPaz, Madrid, Spain.; Department of Gastroenterology, Infectiology and Rheumatology (including Nutrition Medicine), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany.; Department of Rheumatology and Clinical Immunology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.; Division of Rheumatology, Department of Medicine, University of Ottawa, Ottawa, ON, Canada; Ottawa Hospital Research Institute, Ottawa, ON, Canada.; Centre for Human Movement and Rehabilitation, School of Health and Society, University of Salford, Salford, Greater Manchester, UK.; Department of Rheumatology, Ghent University, Ghent University Hospital, Ghent, Belgium.; School of Healthcare Sciences, Cardiff University, Wales, UK.; Rheumatology Unit, Department of Medicine and Public Health, AOU and University of Cagliari, Cagliari, Italy.; Axial Spondyloarthritis International Federation (ASIF), London, UK.; Department of Rheumatology, Hôpital Cochin, University Paris Cité, Paris, France.; PMR Department, Rheumatology Division, Marmara University School of Medicine, Istanbul, Turkey.; Department of Rheumatology, Cairo University, Cairo, Egypt.; Department of Rheumatology and Immunology, Singapore General Hospital, Singapore; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.; Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands.; Rheumatology Unit, Hospital Italiano de La Plata - Universidad Nacional de La Plata, La Plata, Argentina.; Health & Territory Research (HTR), Universidad de Sevilla, Seville, Spain.; Semmelweis University, Budapest, Hungary.; Division of Rheumatology, University of California San Francisco, San Francisco, CA, USA.; Department of Rheumatology, Physical and Rehabilitation Medicine, Clinical University Centre, Sestre Milosrdnice, Zagreb, Croatia.; Department of Rheumatology and Immunology, Chinese PLA General Hospital, Beijing, China.; Department of Nephrology and Rheumatology, Kyorin University School of Medicine, Tokyo, Japan.; Department of Rheumatology and Clinical Immunology, Amsterdam University Medical Center, Amsterdam, The Netherlands; Department of Rheumatology, Zuyderland Medical Center, Heerlen, The Netherlands.; Department of Rheumatology & Immunology, Singapore General Hospital, Duke-NUS Medical School, Singapore.; Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK; Department of Rheumatology, Division of Medicine, University College London, London, UK.; NIHR Leeds Biomedical Research Centre, Leeds Teaching Hospitals Trust and Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, UK.; Department of Rheumatology & Immunology, SVP Hospital & Smt. NHL Municipal Medical College, Ahmedabad, India; Department of Rheumatology, Marengo CIMS Hospital & RheumaCARE, Ahmedabad, India.; Rheumatology Department Cochin Hospital, APHP, INSERM U-1153, Centre de Recherche en Epidémiologie et Statistiques, Université Paris Cité, Paris, France.; Rheumatology Department, King's College Hospital, Centre for Rheumatic Diseases, Centre for Education, King's College London, London, UK.; Department of Internal Medicine and Rheumatology, Klinikum Bielefeld, University of Bielefeld, Bielefeld, Germany.; Rheumalogy Division, Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brazil.; Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands; NOVA Medical School, UNL, Lisbon, Portugal.; Department of Allergy, Immunology & Rheumatology, Chung Shan Medical University Hospital, Taichung, Taiwan; Department of Nursing, Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan; Graduate Institute of Integrated Medicine, China Medical University, Taichung, Taiwan.; Rheumazentrum Ruhrgebiet, Herne and Ruhr-University, Bochum, Germany.; Department of Rheumatology, Leiden University, Leiden, The Netherlands.