1. Amsterdam Rheumatology and Immunology Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands, and Zuyderland Medical Center; Heerlen The Netherlands
2. Leiden University Medical Center, Leiden, The Netherlands, and Ghent University Hospital; Ghent Belgium
3. Maasstad Hospital; Rotterdam The Netherlands
4. Leiden University Medical Center; Leiden The Netherlands
5. Diakonhjemmet Hospital; Oslo Norway
6. University of Padua; Padua Italy
7. Amsterdam Rheumatology and Immunology Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands, and UCB; Brussels Belgium
8. Amsterdam Rheumatology and Immunology Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands and Zuyderland Medical Center; Heerlen The Netherlands