1. SUVA (Swiss National Accident Insurance Fund), Luzern, Switzerland
2. Department of Medical Biometry, Institute for Quality and Efficiency in Health Care (IQWiG), Cologne, Germany
3. Department of Surgery, Alfred Krupp Krankenhaus Steele, Essen, Germany
4. Faculty of Health Sciences, University of Witten-Herdecke, Witten, North Rhine-Westphalia, Germany
5. Department of General and Visceral Surgery, Evangelische Klinik Koeln-Weyertal, Weyertal 76, D-50931Cologne, Germany