[1] Dept Gen Visceral & Transplantat Surg, Aachen, Germany
[2] RWTH Aachen Univ Hosp, Dept Med Stat, Aachen, Germany
[3] Helios Hosp Emil von Behring, Dept Gen Visceral & Minimal Invas Surg, Berlin, Germany
[4] RWTH Aachen Univ Hosp, Dept Gen Visceral & Transplantat Surg, D-52074 Aachen, Germany