1. Department of Internal Medicine, St. Vincent Hospital, College of Medicine, the Catholic University of Korea, Suwon, Korea
2. Department of Internal Medicine, Incheon St. Mary's Hospital, College of Medicine, the Catholic University of Korea, Incheon, Korea
3. Department of Internal Medicine, Uijeongbu St. Mary's Hospital, College of Medicine, the Catholic University of Korea, Uijeongbu, Korea