1. Department of Rehabilitation Medicine, University of Groningen, University Medical Center Groningen, PO Box 30002, 9750 RA Haren, the Netherlands
2. Faculty of Behavioral, Management, and Social Sciences, University of Twente, Enschede, the Netherlands
3. Department of Rehabilitation Medicine, University of Groningen, University Medical Center Groningen
4. Department of Rehabilitation Medicine and Department of Oral and Maxillofacial Surgery, University of Groningen, University Medical Center Groningen
5. Department of Epidemiology, University of Groningen, University Medical Center Groningen