1. Department of Internal Medicine, Chung-Ang University College of Medicine, Seoul, Korea.
2. Department of Internal Medicine, The Catholic University of Korea College of Medicine, Daejeon, Korea.
3. Department of Internal Medicine, Korea University College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Sungkyunkwan University School of Medicine, Seoul, Korea.
5. Department of Internal Medicine, Inje University College of Medicine, Seoul, Korea.
6. Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea.