1. Department of Family Medicine, Korea University College of Medicine , Seoul , Republic of Korea
2. Department of Statistics and Actuarial Science, Soongsil University , Seoul , Republic of Korea
3. Department of Medical Statistics, College of Medicine, The Catholic University of Korea , Seoul , Republic of Korea
4. Department of Family Medicine, Uijeongbu Eulji Medical Center, Eulji Unversity , Gyeonggi-do , Republic of Korea