1. Department of Internal Medicine, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Korea.
2. Department of Internal Medicine, Hanyang University Guri Hospital, Hanyang University College of Medicine, Guri, Korea.
3. Department of Statistics and Actuarial Science, Soongsil University, Seoul, Korea.
4. Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.