1. Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
2. Department of Internal Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
3. Department of Internal Medicine, Kyung Hee University School of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Soonchunhyang University College of Medicine, Cheonan, Korea.
5. Department of Internal Medicine, Dongguk University College of Medicine, Goyang, Korea.
6. Department of Internal Medicine, Konyang University College of Medicine, Daejeon, Korea.
7. Department of Internal Medicine, Chungbuk National University Hospital, Cheongju, Korea.
8. Department of Internal Medicine, Jeju National University School of Medicine, Jeju, Korea.
9. Department of Internal Medicine, Hallym University Dongtan Sacred Heart Hospital, Seoul, Korea.
10. Department of Internal Medicine, Seoul Paik Hospital, Inje University College of Medicine, Seoul, Korea.
11. Department of Internal Medicine, St. Vincent's Hospital, The Catholic University of Korea College of Medicine, Suwon, Korea.
12. Department of Internal Medicine, Dankook University College of Medicine, Cheonan, Korea.