1. Amsterdam University Medical Centers, Amsterdam, the Netherlands, and Karolinska Institute Stockholm Sweden
2. Amsterdam University Medical Centers Amsterdam the Netherlands
3. Karolinska Institute and Karolinska University Hospital Stockholm Sweden
4. Vrije Universiteit Amsterdam University Medical Center Amsterdam the Netherlands
5. Copenhagen University Hospital Rigshospitalet, Glostrup, and University of Copenhagen Copenhagen Denmark
6. Diakonhjemmet Hospital and University of Oslo Oslo Norway
7. Helsinki University Hospital and University of Helsinki Helsinki Finland
8. Amsterdam University Medical Centers, Amsterdam, and Amsterdam Rheumatology and Immunology Center Reade the Netherlands
9. Landspitali University Hospital and University of Iceland Reykjavik Iceland
10. Sahlgrenska University Hospital and University of Gothenburg Gothenburg Sweden
11. Diakonhjemmet Hospital Oslo Norway
12. University of Eastern Finland, Jyväskylä Central Hospital Jyväskylä Finland
13. University Hospital of Southern Denmark, Sønderborg, and University of Southern Denmark Odense Denmark