1. Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
2. Division of Gastroenterology, Department of Internal Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Korea.
3. Department of Internal Medicine, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung, Korea.
4. Department of Gastroenterology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.