1. Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
2. Department of Internal Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul, Korea.
3. Department of Internal Medicine, Gyeonggi Provincial Medical Center Paju Hospital, Paju, Korea.
4. Department of Internal Medicine, Jeonbuk National University Medical School, Jeonju, Korea.
5. Department of Internal Medicine, Gyeonggi Provincial Medical Center Suwon Hospital, Suwon, Korea.
6. Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea.
7. Department of Internal Medicine, Chung-Ang University Hospital, Seoul, Korea.
8. Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
9. Department of Internal Medicine, Gangwon-do Wonju Medical Center, Wonju, Korea.
10. Department of Internal Medicine, Kyung Hee University Hospital, Seoul, Korea.
11. Department of Internal Medicine, Inje University Busan Paik Hospital, Busan, Korea.
12. Department of Internal Medicine, Inje University Sanggye Paik Hospital, Seoul, Korea.