[1] Dongguk Univ, Gyeongju Hosp, Dept Internal Med, Div Pulm Allergy & Crit Care Med,Coll Med, Gyeongju, South Korea
[2] Korea Univ, Guro Hosp, Dept Internal Med, Div Pulm Allergy & Crit Care Med,Coll Med, Seoul, South Korea
[3] Hanyang Univ, Hanyang Med Ctr, Dept Internal Med, Div Pulm Med & Allergy,Coll Med, Seoul, South Korea
[4] Sungkyunkwan Univ, Samsung Biomed Res Inst, Sch Med, Suwon, South Korea
[5] Sungkyunkwan Univ, Kangbuk Samsung Hosp, Dept Med, Div Pulm & Crit Care Med,Sch Med, Seoul, South Korea
[6] Konkuk Univ, Med Ctr, Sch Med, Dept Internal Med, Seoul, South Korea
[7] Soongsil Univ, Dept Stat & Actuarial Sci, 369 Sangdo Ro, Seoul 06978, South Korea