1. Department of Internal Medicine, The Catholic University of Korea School of Medicine, Seoul, Korea.
2. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Internal Medicine, Pusan National University College of Medicine, Busan, Korea.
4. Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Korea.
5. Department of Internal Medicine, Soon Chun Hyang University College of Medicine, Seoul, Korea.
6. Department of Internal Medicine, Korea University College of Medicine, Seoul, Korea.