1. Department of Rheumatology and Immunology, Medical University Graz, Graz, Austria
2. Rheumatology Service, Hospital of Bruneck, Bruneck, Italy
3. Medical Centre for Rheumatology Berlin-Buch, Immanuel Krankenhaus Berlin, Berlin, Germany
4. Institute for Medical Informatics, Statistics and Documentation, Medical University of Graz, Graz, Austria
5. Department of Internal Medicine III, Oncology, Haematology, Rheumatology and Clinical Immunology, University Hospital Bonn, Venusberg-Campus 1, Bonn, Nordrhein-Westfalen 53127, Germany