[1] Aarhus Univ Hosp, Dept Surg, Sect Coloproctol, Tage Hansens Gade 2, DK-8000 Aarhus C, Denmark
[2] Lillebaelt Hosp, Dept Surg, Kolding, Denmark
[3] Hvidovre Univ Hosp, Gastroenterol Unit, Hvidovre, Denmark
[4] Aalborg Univ Hosp, Dept Gastrointestinal Surg, Aalborg, Denmark
[5] Odense Univ Hosp, Dept Surg A, Odense, Denmark
[6] Copenhagen Univ Hosp, Rigshosp, Dept Surg & Transplantat, Copenhagen, Denmark
[7] Herlev Hosp, Dept Surg, Herlev, Denmark
[8] Aarhus Univ Hosp, Dept Gastroenterol & Hepatol, Aarhus C, Denmark
[9] Aarhus Univ Hosp, Dept Clin Epidemiol, Aarhus N, Denmark