1. Internal Medicine Department, La Tour Hospital and University of Geneva, Geneva, Switzerland
2. Department of specilaties of Internal Medicine, Divison of Gastroenterology, Geneva University Hospital, Geneva, Switzerland
3. Division of Gastroenterology, McGill University Health Centre, McGill University, Montreal, Quebec, Canada
4. Department of Epidemiology and Biostatistics and Occupational Health, McGill University Health Centre, McGill University, Montreal, Quebec, Canada