[1] Hvidovre Univ Hosp, Ctr Surg Res CSR, Surg Div, Gastrounit, Hvidovre, Denmark
[2] Zealand Univ Hosp, Ctr Surg Sci, Dept Surg, Koge, Denmark
[3] Sorlandet Hosp Trust, Surg Dept, Kristiansand, Norway
[4] Univ Gothenburg, SSORG Scandinavian Surg Outcomes Res Grp, Dept Surg, Inst Clin Sci,Sahlgrenska Acad, Gothenburg, Sweden
[5] Sahlgrens Univ Hosp, Dept Surg, Gothenburg, Region Vastra G, Sweden
[6] Herlev Hosp, Dept Surg, Herlev, Denmark