1. Department of Rheumatology, University Hospital Zurich, Gloriastrasse 25, 8091 Zurich, Switzerland
2. Department of Rheumatology, Bethesda Hospital, Gellertstrasse 144, 4020 Basel, Switzerland
3. Department of Rheumatology, Zuger Kantonsspital, Landhausstrasse 11, 6340 Baar, Switzerland
4. Horten Centre for Patient Oriented Research and Knowledge Transfer, University of Zurich, Pestalozzistraße 24, 8091 Zurich, Switzerland