1. Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
2. Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
3. Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea.
4. Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seongnam, Korea.
5. Department of Preventive Medicine, Ajou University School of Medicine, Suwon, Korea.