1. Department of Family Medicine, Uijeongbu Eulji Medical Center, Eulji University, Gyeonggi-do 11759, Republic of Korea
2. Department of Family Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul 08308, Republic of Korea
3. Department of Family Medicine, H plus Yang Ji Hospital, Seoul 08779, Republic of Korea
4. Department of Family Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Republic of Korea