[1] Konkuk Univ, Sch Med, Chungju Hosp, Div Pulm & Crit Care Med,Dept Internal Med, Chungju, South Korea
[2] Konkuk Univ, Sch Med, Chungju Hosp, Dept Internal Med, Chungju, South Korea
[3] Univ Ulsan, Coll Med, Asan Med Ctr, Div Pulm & Crit Care Med, Seoul 138736, South Korea