Department of Internal Medicine, Pusan National University Hospital, Pusan National University School of Medicine, Busan, Korea. Biomedical Research Institute, Pusan National University Hospital, Busan, Korea. Department of Internal Medicine, Inje University Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea. Department of Internal Medicine, Inje University Busan Paik Hospital, Inje University College of Medicine, Busan, Korea. Department of Internal Medicine, Busan St. Mary's Hospital, Catholic University of Pusan, Busan, Korea. Department of Internal Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea. Department of Internal Medicine, Daedong Hospital, Busan, Korea. Department of Internal Medicine, Kosin University Gospel Hospital, Kosin University College of Medicine, Busan, Korea. Department of Internal Medicine, Dong-A Medical Center, Dong-A University College of Medicine, Busan, Korea. Biomedical Research Institute, Pusan National University Hospital, Busan, Korea. injkim@pusan.ac.kr.