1. Department of Family Medicine, Seoul National University Hospital, Seoul, Korea.
2. Department of Family Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
3. Center for Medical Informatics, Seoul National University Bundang Hospital, Seongnam, Korea.
4. Department of Pediatrics, Seoul National University Bundang Hospital, Seongnam, Korea.
5. Health Promotion Center, Seoul National University Bundang Hospital, Seongnam, Korea.