[1] Sungkyunkwan Univ, Kangbuk Samsung Hosp, Dept Internal Med, Div Nephorol,Sch Med, Seoul, South Korea
[2] CHA Univ, CHA Bundang Med Ctr, Dept Internal Med, Sch Med, Seongnam, South Korea
[3] Hanyang Univ, Coll Med, Dept Internal Med, Guri Hosp, Guri, South Korea
[4] Soongsil Univ, Dept Stat & Actuarial Sci, Seoul, South Korea
[5] Sungkyunkwan Univ, Kangbuk Samsung Hosp, Dept Internal Med, Div Endocrinol & Metab,Sch Med, 29 Saemunan Ro, Seoul 03181, South Korea