1. Center for Clinical Epidemiology Odense University Hospital Odense C Denmark
2. Research Unit of Clinical Epidemiology, Department of Clinical Research University of Southern Denmark Odense C Denmark
3. Center for Crohn's and Colitis, Brigham and Women's Hospital, Harvard Medical School Boston Massachusetts USA
4. Department of Medical Gastroenterology S Odense University Hospital Odense C Denmark
5. Research Unit of Medical Gastroenterology, Department of Clinical Research University of Southern Denmark Odense C Denmark