1. Department of Rheumatology, Leiden University Medical Center, Leiden, the Netherlands
2. Department of Rheumatology, Amsterdam Rheumatology & Immunology Center (ARC), Amsterdam, the Netherlands
3. Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway
4. Rheumatology Unit, Department of Medicine, University of Padova, Padova, Italy
5. Department of Rheumatology, University of Göteborg, Göteborg, Sweden