1. Department of General, Visceral, and Thoracic Surgery, Kreisklinik Bad Neustadt/Saale, Bad Neustadt/Saale, Germany.
2. Department of Surgery, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany.
3. Institute of Biometrics and Medical Informatics, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany.
4. Department of Surgery,Vivantes Klinikum Spandau, Berlin, Germany.