1. Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
2. Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
3. Department of Family Medicine, Korea University College of Medicine, Seoul, Korea
4. Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
5. Department of Internal Medicine, SMG-SNU Boramae Medical Center, Seoul, Korea