1. Department of Anaesthesiology and Intensive Care Medicine, Copenhagen University Hospital Rigshospitalet, and Departments of Gastrointestinal Surgery, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark
2. Department of Clinical Epidemiology, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark
3. Copenhagen University Hospital Hvidovre, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark
4. Copenhagen University Hospital Herlev, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark
5. Department of Gastrointestinal Surgery, Regional Hospital Herning, Herning, Denmark
6. Copenhagen University Hospital Køge, Copenhagen, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark
7. Department of Anaesthesiology and Intensive Care Medicine, Odense University Hospital, Odense, Denmark
8. Department of Gastrointestinal Surgery, Regional Hospital Kolding, Kolding, Denmark