1. Department Internal Medicine, Division of Gastroenterology, King Abdulaziz Medical City, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
2. King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
3. Ministry of the National Guard-Health Affairs, Riyadh, Saudi Arabia
4. Department of Medicine, University of Maryland Medical Center, Baltimore, MD, USA
5. Department of Medicine, Division of Gastroenterology, Southern Illinois University, School of Medicine, Springfield, IL, USA