[1] Kantonsspital, Dept Gen Visceral Endocrine & Transplantat Surg, CH-9007 St Gallen, Switzerland
[2] Heidelberg Univ, Med Fac Mannheim, Univ Med Mannheim, Dept Surg, D-68167 Mannheim, Germany
[3] Spital Linth, Dept Surg, CH-8730 Uznach, Switzerland
[4] Heidelberg Univ, Inst Med Biometry & Informat, D-69120 Heidelberg, Germany