1. Center of Excellence in Health Care Research of the German Pain Association, Institute of Neurological Sciences, Nuernberg, Germany
2. O. Meany Consultancy GmbH, Hamburg, Germany
3. Interdisciplinary Pain and Palliative Care Center, Goeppingen, Germany
4. Interdisciplinary Pain Center, Kevelaer, Germany
5. Center for Internal Medicine and Endoscopy, Starnberg, Germany