1. Department of Internal Medicine, Seoul Paik Hospital, Inje University College of Medicine, Seoul, Korea.
2. Department of Internal Medicine, Yeouido St. Mary's Hospital, The Catholic University of Korea, College of Medicine, Seoul, Korea.
3. Department of Internal Medicine, Guro Hospital, Korea University College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Ansan Hospital, Korea University College of Medicine, Ansan, Korea.
5. Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
6. Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
7. Department of Internal Medicine, Ulsan University College of Medicine, Asan Medical Center, Seoul, Korea.
8. Department of Internal Medicine, Chung-Ang University College of Medicine, Seoul, Korea.
9. Department of Internal Medicine, Hanyang University College of Medicine, Seoul, Korea.
10. Department of Internal Medicine, Samsung Medical Center, Sungkyunkwan University College of Medicine, Seoul, Korea.