1. Department of Medicine (Division of Gastroenterology), University of Western Ontario, London, Canada
2. Department of Medicine (Division of Gastroenterology), University of Toronto, Toronto, Ontario, Canada
3. Department of Medicine (Division of Gastroenterology), University of Calgary, Calgary, Alberta, Canada
4. Departments of Medicine (Division of Gastroenterology and Hepatology) and of Biometry, Bioinformatics and Epidemiology, Medical University of South Carolina, Charleston, South Carolina, USA