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