1. Universidad de Antioquia; Department of General Surgery; Street 67 N 53-108 Medellin Colombia
2. London School of Hygiene & Tropical Medicine; Cochrane Injuries Group; Keppel Street London UK WC1E 7HT
3. University of Perugia; Department of General Surgery; Terni Italy
4. Lister Hospital - East and North Herts NHS Trust; General and Colorectal Surgery; Coreys Mill Lane Stevenage Hertfordshire UK SG1 4AB