1. The University of Texas at Austin and Dell Medical School, Austin, Texas, USA.
2. University Medical Center, Utrecht, The Netherlands.
3. Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Behavioral Medical Services, Boston, Massachusetts, USA.
4. Department of Sport, Health Sciences and Social Work, Oxford Brookes University, Oxford, UK.
5. University of Oxford. Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Oxford, UK.