[1] Yonsei Univ, Coll Med, Gangnam Severance Hosp, Dept Family Med, Seoul 06273, South Korea
[2] Yonsei Univ, Coll Med, Yongin Severance Hosp, Dept Family Med, Yongin 16995, South Korea
[3] Eulji Univ, Sch Med, Nowon Eulji Med Ctr, Dept Family Med, Seoul 01830, South Korea
[4] Hanyang Univ, Grad Sch, Dept Med, Seoul 04763, South Korea