[1] Univ Cagliari, Dept Surg Sci, Cagliari, Italy
[2] Azienda Osped Univ Cagliari, Cagliari Univ Hosp D Casula, Emergency Surg Unit, Cagliari, Italy
[3] Pisa Univ Hosp, Dept Gen Emergency & Trauma Surg, Pisa, Italy
[4] Ist Ric Farmacol Mario Negri IRCSS, Ctr Polit Regolatorie Sanita, Milan, Italy
[5] IRCCS Ist Ortoped Galeazzi, Unit Clin Epidemiol, Milan, Italy
[6] Forth Valley Royal Hosp, Dept Gen Surg, Larbert, England
[7] Macerata Gen Hosp, Dept Gen & Emergency Surg, Macerata, Italy
[8] Univ Naples Federico II, Dept Publ Hlth, Naples, Italy
[9] Bufalini Hosp, Dept Gen Emergency & Trauma Surg, Cesena, Italy
[10] Univ Naples Federico II, Dept Publ Hlth, Minimally Invas Gen & Oncol Surg Unit, Naples, Italy
[11] Univ Cagliari, Dept Surg Sci, Policlin Univ D Casula, Azienda Osped Univ Cagliari, SS 554,Km 4,500, I-09042 Monserrato, Italy