[1] Unit of Gastroenterology, Karolinska Institute, Huddinge University Hospital
[2] Unit of Gastroenterology, Huddinge University Hospital
[3] Department of Gastroenterology, Leuven University Hospital
[4] Akademisches Lehrkrankenhaus, Univerzität zu Köln, Leverkusen
[5] Dept. of Gastroenterol. and Hepatol., University Hospital, Leiden
[6] Medical Department, University Hospital, Umeå
[7] Department of Gastroenterology, University Hospital, Linköping
[8] Gastroenterology Unit, Radcliffe Infirmary, Oxford
[9] Medical Department C, Herlev University Hospital
[10] Medical Department, Hammersmith Hospital, London
[11] Dept. of Biostatist. and Data Proc., Astra Draco, Lund
[12] Dept. of Clin. Res. and D., Astra Draco, Lund