1. Department of Gastroenterology; Asan Digestive Disease Research Institute; Asan Medical Center; University of Ulsan College of Medicine; Seoul Korea
2. Health Screening and Promotion Center; Asan Medical Center; University of Ulsan College of Medicine; Seoul Korea
3. Department of Internal Medicine; Jeju National University School of Medicine; Jeju Korea
4. Department of Clinical Epidemiology and Biostatistics; Asan Medical Center; University of Ulsan College of Medicine; Seoul Korea