1. Surgical Research Unit, Odense University Hospital, 5700 Svendborg, Denmark
2. Department of Clinical Research, University of Southern Denmark, 5230 Odense, Denmark
3. Department of Medicine, OUH Svendborg Sygehus, 5700 Svendborg, Denmark
4. Department of Social Medicine and Public Health, Pomeranian Medical University, 70-204 Szczecin, Poland