1. Department of Internal Medicine, Hanyang University College of Medicine, Seoul, Korea.
2. Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
3. Department of Internal Medicine, Soonchunhyang University College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Busan Paik Hospital, Inje University School of Medicine, Busan, Korea.
5. Department of Internal Medicine, Pusan National University College of Medicine, Busan, Korea.