1. University of Perugia; Department of General Surgery; Terni Italy
2. Regional Health Authority of Umbria; Health Planning Service; Via Mario Angeloni 61 Perugia Umbria Italy 06124
3. Lister Hospital - East and North Herts NHS Trust; General and Colorectal Surgery; Coreys Mill Lane Stevenage Hertfordshire UK SG1 4AB
4. Derriford Hospital; Department of Pharmacy; Plymouth UK
5. San Luca Hospital, Auxologic Institute; Milan Italy
6. Regional Health Authority of Umbria; Epidemiology Department; Via Mario Angeloni, 61 Perugia Italy 06124