1. Institute for Quality Assurance in Surgical Care, Otto-von-Guericke University Medical School, Germany
2. Department of General, Abdominal and Vascular Surgery, Otto-von-Guericke University Medical School, Germany
3. Department of Surgery, Carl-Thiem Hospital, Cottbus, Germany
4. StatConsult Institute for Clinical and Healthcare Research, Magdeburg, Germany
5. Department of General, Abdominal and Thoracic Surgery, District Hospital Bad Neustadt/Saale, Bad Neustadt, Germany