1. Department of Family Medicine, Seoul National University Hospital, Seoul, Korea.
2. Department of Family Medicine, Healthcare System Gangnam Center, Seoul National University Hospital, Seoul, Korea.
3. Department of Medicine, Seoul National University College of Medicine, Seoul, Korea.
4. Department of Family Medicine, Seoul National University Health Service Center, Seoul, Korea.
5. Department of Social and Preventive Medicine, Inha University School of Medicine, Incheon, Korea.
6. Department of Internal Medicine, Healthcare System Gangnam Center, Seoul National University Hospital, Seoul, Korea.