1. Department of Surgery, University of Toronto, Toronto, Canada
2. Department of Surgery, University of Berne, Berne, Switzerland
3. Dalla Lana School of Public Health, University of Toronto, Toronto, Canada
4. Department of Surgery, University of Western Ontario, London, Ontario, Canada
5. Department of Surgery, University of Basel, Basel, Switzerland
6. Department of Surgery, University of Zurich, Zurich, Switzerland