1. Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
2. Department of Internal Medicine, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Suwon, Korea.
3. Department of Internal Medicine, Chung-Ang University College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea.
5. Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
6. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
7. Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea.