1. Department of Epidemiology, Erasmus University Medical Center Rotterdam, Rotterdam, The Netherlands
2. Department of Radiology, Erasmus University Medical Center Rotterdam, Rotterdam, The Netherlands
3. Clinic for Complementary Medicine Rodenrijs, Berkel en Rodenrijs, The Netherlands
4. Clinic for Acupuncture and Physical Therapy, Zandvoort, The Netherlands
5. Unipolis, Amsterdam, The Netherlands
6. Department of Health Policy and Management, Harvard School of Public Health, Boston, USA