1. Department of Gastroenterological Surgery, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
2. Department of Surgery, Surgical Research Unit, Medical Research Centre, Oulu University Hospital, University of Oulu, Oulu, Finland
3. Department of Surgery, Central Hospital of Central Finland, Jyväskylä, Finland
4. Department of Surgery, Seinäjoki Central Hospital, Seinäjoki, Finland