1. Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA;
2. Center for Clinical Epidemiology, Odense University Hospital, Odense, Denmark;
3. Research Unit of Clinical Epidemiology, Department of Clinical Research, University of Southern Denmark, Odense, Denmark;
4. Division of Gastroenterolgy and Hepatology, Tufts University School of Medicine, Boston, Massachusetts, USA;
5. Department of Medical Gastroenterology S, Odense University Hospital, Odense, Denmark;
6. Research Unit of Medical Gastroenterology, Department of Clinical Research, University of Southern Denmark, Odense, Denmark.