[1] Ersta Hosp, Ctr Gastrointestinal Dis, S-11691 Stockholm, Sweden
[2] Danderyd Hosp, Dept Clin Sci, Stockholm, Sweden
[3] Karolinska Inst, Dept Clin Sci Intervent & Technol, Stockholm, Sweden
[4] Karolinska Inst, Inst Mol Med & Surg, Stockholm, Sweden
[5] Univ Orebro, Orebro, Sweden
[6] Univ Hosp, Orebro, Sweden
[7] Univ Auckland, Dept Surg, Auckland 1, New Zealand