1. Digestive Disease Center and Research Institute, Department of Internal Medicine, Soonchunhyang University School of Medicine, Bucheon, Korea
2. Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
3. Department of Clinical Research Design and Evaluation, Samsung Advanced Institute for Health Sciences & Technology (SAIHST), Sungkyunkwan University, Seoul, Korea
4. Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
5. Center for Clinical Epidemiology, Samsung Medical Center, Sungkyunkwan University, Seoul, Korea
6. Department of Epidemiology and Medicine and Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins Medical Institutions, Baltimore, MD, USA