[1] Yonsei Univ, Dept Internal Med, Div Rheumatol, Coll Med, Seoul, South Korea
[2] Soongsil Univ, Dept Stat & Actuarial Sci, 369 Sangdo Ro, Seoul 06978, South Korea
[3] Yonsei Univ, Coll Med, Dept Internal Med, Div Gastroenterol, 20 Eonju Ro 63 Gil, Seoul 06229, South Korea
[4] Inha Univ Hosp, Dept Neurol, Incheon, South Korea
[5] Univ Ulsan, Asan Med Ctr, Dept Gastroenterol, Coll Med, Seoul, South Korea