[1] Seoul Natl Univ, Coll Med, Dept Internal Med, Div Rheumatol, 101 Daehak Ro, Seoul 03080, South Korea
[2] Seoul Natl Univ, Boramae Med Ctr, Seoul Metropolitan Govt, Dept Internal Med, Seoul, South Korea
[3] Seoul Natl Univ, Bundang Hosp, Div Rheumatol, Dept Internal Med, Gyeonggi Do, South Korea
[4] Seoul Natl Univ, Seoul Natl Univ Hosp, Coll Med, Div Med Stat,Med Res Collaborating Ctr, Seoul, South Korea