1. Department of Medical Sciences, Unit of Rheumatology, Uppsala University, Uppsala, Sweden
2. Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
3. Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
4. Department of Medicine, Unit of Clinical Epidemiology, Karolinska Institutet, Stockholm, Sweden
5. Center of Hematology, Karolinska University Hospital, Stockholm, Sweden
6. Division of Rheumatology, Department of Medicine, University of Massachusetts Medical School, Worcester, MA, USA
7. Rheumatology Unit, Department of Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden