1. Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
2. Department of Internal Medicine, Inje University Ilsan Paik Hospital, Ilsan, Korea
3. Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
4. Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Korea
5. Division of Clinical Epidemiology, Medical Research Collaborating Center, Seoul National University Hospital, Seoul, Korea
6. Department of Statistics, Kyungpook National University, Daegu, Korea
7. Department of Prevention and Management, Inha University Hospital, Incheon, Korea
8. Department of Internal Medicine, Seoul National University Boramae Medical Center, Seoul, Korea