1. Department of General Practice, Erasmus University Medical Center, PO Box 2040, 3000 CA Rotterdam, the Netherlands
2. Department of General Practice, Erasmus University Medical Center
3. Department of Rheumatology and Clinical Immunology, University Medical Center, Utrecht, the Netherlands; and Department of Rheumatology, Tergooi Hospital, Hilversum, the Netherlands
4. Department of Radiology & Nuclear Medicine, Erasmus University Medical Center
5. Department of General Practice, and Department of Orthopedics, Erasmus University Medical Center
6. Department of General Practice, Erasmus University Medical Center.*S.M.A. Bierma-Zeinstra and P.A.J. Luijsterburg contributed equally to the work