[1] Univ Ulsan, Div Pulm & Crit Care Med, Dept Internal Med, Asan Med Ctr,Coll Med, Seoul, South Korea
[2] Ewha Womans Univ, Mokdong Hosp, Div Pulm & Crit Care Med, Dept Internal Med, Seoul, South Korea
[3] Univ Ulsan, Dept Gastroenterol & Inflammatory Bowel Dis Ctr, Asan Med Ctr, Coll Med, 88 Olympic ro 43 Gil, Seoul 05505, South Korea