1. Center for Internal Medicine and Dermatology, Department of Psychosomatic Medicine, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 12203 Berlin, Germany
2. Department of Psychosomatic Medicine and Psychotherapy, University Hospital Tübingen, 72076 Tübingen, Germany
3. Quantitative Health Sciences, Outcomes Measurement Science, University of Massachusetts Medical School, Worcester, MA 01655, USA
4. Department of Psychosomatic Medicine, DRK Kliniken Berlin Wiegmann Klinik, 14050 Berlin, Germany