[1] Seoul Natl Univ Hosp, Dept Internal Med, Seoul, South Korea
[2] Korea Univ, Dept Biostat, Coll Med, Seoul, South Korea
[3] Ewha Womans Univ, Seoul Hosp, Dept Internal Med, Coll Med, Seoul, South Korea
[4] Inje Univ, Dept Internal Med, Busan Paik Hosp, Busan, South Korea
[5] Natl Med Ctr, Dept Internal Med, Seoul, South Korea
[6] Seoul Natl Univ, Dept Internal Med, Med Coll, 101 Daehakro, Seoul 03080, South Korea