1. Pain Management and Research Center; University Medical Center Maastricht; Maastricht The Netherlands
2. Adelante Centre of Expertise in Rehabilitation; Hoensbroek The Netherlands
3. Department of Rehabilitation Medicine; Research School CAPHRI; Maastricht University; Maastricht The Netherlands
4. Department of Anaesthesiology; VU University Medical Center and The Institute for Research in Extramural Medicine; Amsterdam The Netherlands
5. Department of Methodology and Statistics; Research School CAPHRI; Maastricht University; Maastricht The Netherlands