[1] Chung Ang Univ, Coll Med, Dept Psychiat, Seoul 156756, South Korea
[2] Chung Ang Univ, Coll Med, Dept Internal Med, Seoul 156756, South Korea
[3] Yonsei Univ, Coll Med, Dept Internal Med, Div Pulmonol,Kangnam Severance Hosp, Seoul, South Korea
[4] Chonnam Natl Univ Hosp, Dept Internal Med, Gwangju, South Korea
[5] Konkuk Univ, Dept Internal Med, Sch Med, Seoul, South Korea
[6] Ewha Womans Univ, Dept Internal Med, Sch Med, Seoul, South Korea
[7] Yonsei Univ, Coll Med, Dept Internal Med, Div Pulmonol,Inst Chest Dis, Seoul, South Korea
[8] Seoul Natl Univ, Coll Med, Dept Internal Med, Div Pulmonol, Seoul 151, South Korea
[9] Ajou Univ, Sch Med, Dept Internal Med, Suwon 441749, South Korea