1. Gastroenterology Division, Department of Medicine 1443, King Abdulaziz Medical City, P.O. Box 22490, Riyadh 11426, Saudi Arabia
2. Department of Medicine 1443, King Abdulaziz Medical City, P.O. Box 22490, Riyadh 11426, Saudi Arabia
3. Gastroenterology Division, Department of Medicine, King Fahad Medical City, P.O. Box 59046, Riyadh 11525, Saudi Arabia