[1] Sungkyunkwan Univ, Samsung Med Ctr, Sch Med, Dept Med, Seoul 60351, South Korea
[2] Dongguk Univ, Sch Med, Ilsan Hosp, Dept Internal Med, Goyang 10326, South Korea
[3] Ewha Womans Univ, Sch Med, Dept Internal Med, Seoul 07804, South Korea
[4] Kyungpook Natl Univ, Med Ctr, Sch Med, Dept Internal Med, Daegu 37224, South Korea