1. Department of Internal Medicine, University of Ulsan College of Medicine, Seoul, Korea.
2. Department of Internal Medicine, Ajou University College of Medicine, Suwon, Korea.
3. Department of Internal Medicine, The Catholic University of Korea College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Yeungnam University College of Medicine, Daegu, Korea.
5. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
6. Department of Internal Medicine, Chung-Ang University College of Medicine, Seoul, Korea.
7. Department of Internal Medicine, Sungkyunkwan Universitiy School of Medicine, Seoul, Korea.
8. Department of Medicine, Korea University Graduate School, Seoul, Korea.