1. Department of Medicine; Faculty of Health, Witten/Herdecke University; Cologne Germany
2. International Affairs Unit; Institute for Quality and Efficiency in Health Care (IQWiG); Cologne Germany
3. Institute for Research in Operative Medicine; Witten/Herdecke University; Cologne Germany
4. Brandenburg Medical School - Theodor Fontane; Faculty of Health; Neuruppin Germany
5. Interdisciplinary Centre for Health Services Research; Witten/Herdecke University; Witten Germany