1. Department of Internal Medicine, Korea University Guro Hospital, Seoul, Korea.
2. Department of Internal Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
3. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Chungnam National University, Daejeon, Korea.
5. Department of Internal Medicine, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, Korea.
6. Department of Internal Medicine, Dong-A University Hospital, Busan, Korea.
7. Department of Internal Medicine, Chonnam National University Hwasun Hospital, Hwasun, Korea.
8. Department of Internal Medicine, SoonChunHyang University Hospital, Seoul, Korea.
9. Department of Internal Medicine, Pusan National University Hospital, Busan, Korea.
10. Department of Internal Medicine, Ulsan University Hospital, Ulsan, Korea.
11. Department of Internal Medicine, Gachon University Gil Medical Center, Incheon, Korea.
12. Department of Internal Medicine, Youngnam University Hospital, Daegu, Korea.
13. Department of Internal Medicine, National Cancer Center, Goyang, Korea.
14. Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
15. Department of Internal Medicine, St. Vincent Hospital, The Catholic University of Korea, Suwon, Korea.
16. Department of Internal Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea.