1. Division of Gastroenterology , Bangkok Metropolitan Administration General Hospital , Bangkok 10100 , Thailand
2. Division of Gastroenterology , Department of Medicine , Faculty of Medicine , Chulalongkorn University and King Chulalongkorn Memorial Hospital , Thai Red Cross Society , Bangkok 10330 , Thailand
3. Division of Gastroenterology , Sawanpracharak Hospital , Nakhon Sawan 60000 , Thailand
4. Division of Gastroenterology , Surin Hospital , Surin 32000 , Thailand
5. Division of Gastroenterology , HRH Princess Maha Chakri Sirindhorn Medical Center–MSMC Hospital , Nakhon Nayok 26120 , Thailand
6. Division of Gastroenterology , Maharat Nakhonratchasima Hospital , Nakhon Ratchasima 30000 , Thailand
7. Division of Gastroenterology , Maharaj Nakhonsithammarat Hospital , Nakhon Sithammarat 80000 , Thailand
8. Division of Gastroenterology , Chonburi Hospital , Chonburi 20000 , Thailand
9. Division of Gastroenterology , Bangkok Hospital , Bangkok 10310 , Thailand
10. Department of Surgery , Rajavithi Hospital , Bangkok 10400 , Thailand
11. Division of Gastroenterology , Rajavithi Hospital , Bangkok 10400 , Thailand
12. Division of Gastroenterology , Department of Medicine , Faculty of Medicine , Thammasat University Hospital , Pathum Thani 12120 , Thailand