1. Department for General, Visceral, Vascular, Thoracic and Pediatric Surgery of the Kempten Clinic, Kempten, Germany.
2. Department for General and Visceral Surgery of the Ulm University Clinic, Ulm, Germany.
3. Working Group "Healthcare Research" at the Department for General and Visceral Surgery of the Ulm University Clinic, Ulm, Germany.