1. From the Section of Gastroenterology, Department of Medicine, Research Centre, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
2. From the Department of Tropical Medicine and Gastroenterology, Assiut University Hospital and Faculty of Medicine, Assiut, Egypt
3. From the Department of Biostatistics, Epidemiology and Scientific Computing, Research Centre, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia