1. Department of Internal Medicine, Yeosu Chonnam Hospital, Yeosu, Korea.
2. Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, Korea.
3. Department of Internal Medicine, Gachon University, Gil Hospital, Incheon, Korea.
4. Department of Internal Medicine, Inje University Busan Paik Hospital, Busan, Korea.
5. Department of Internal Medicine, Seoul National University Boramae Medical Center, Seoul, Korea.
6. Department of Internal Medicine, Severance Hospital, Yonsei University, Seoul, Korea.
7. Department of Internal Medicine, Eulji Medical Center, Eulji University, Seoul, Korea.