1. Centre for Trauma Sciences, Blizard Institute, Queen Mary University of London , London, UK
2. General Surgical Department, Aberdeen Royal Infirmary , Aberdeen, UK
3. Health Services Research Unit, University of Aberdeen , Aberdeen, UK
4. Department of Surgery, Elkabbary Hospital , Alexandria, Egypt
5. Medical Statistics Team, University of Aberdeen , Aberdeen, UK
6. Department of Surgery, Raigmore Hospital , Inverness, UK
7. Division of Trauma and Acute Care Surgery, Department of Surgery, University of Alabama at Birmingham , Birmingham, Alabama, USA