1. Department of Orthopaedics, Rehabilitation and Physical Therapy, Leiden University Medical Center, Leiden, The Netherlands
2. Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands
3. Department of Research, Sint Maartenskliniek, Nijmegen, The Netherlands
4. Department of Rheumatology, Radboud University Medical Center, Nijmegen, The Netherlands