[1] Seoul Natl Univ, Coll Med, SMG SNU Boramae Med Ctr, Dept Internal Med, Seoul, South Korea
[2] Hallym Univ, Kangdong Sacred Heart Hosp, Dept Pulm Allergy & Crit Care Med, Seoul, South Korea
[3] Univ Ulsan, Coll Med, Asan Med Ctr, Dept Internal Med, Seoul, South Korea
[4] Hallym Univ, Sacred Heart Hosp, Div Pulm Allergy & Crit Care Med, Anyang, South Korea
[5] Kyung Hee Univ, Sch Med, Dept Pulm & Crit Care Med, Kyung Hee Univ Hosp Gangdong, Seoul, South Korea
[6] Konkuk Univ, Sch Med, Dept Internal Med, Seoul, South Korea
[7] Catholic Univ Korea, Dept Internal Med, Uijeongbu St Marys Hosp, Coll Med, 271 Cheonbo Ro, Uijongbu 11765, South Korea