1. Department of Orthopaedics, Rehabilitation and Physical Therapy, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
2. Center for Rehabilitation and Rheumatology, Reade, 1056 AA Amsterdam, The Netherlands
3. Department of Rheumatology, Radboud UMC, 6500 GM Nijmegen, The Netherlands
4. Department of Research, Sint Maartenskliniek, 6500 GM Nijmegen, The Netherlands
5. Department of Clinical Epidemiology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands