[1] Soonchunhyang Univ, Bucheon Hosp, Coll Med, Div Rheumatol,Dept Internal Med, 170 Jomaru Ro, Bucheon 14584, South Korea
[2] Samsung Med Ctr, Biostat & Clin Epidemiol Ctr, 81 Irwon Ro, Seoul 06351, South Korea
[3] Natl Med Ctr, Dept Internal Med, Div Rheumatol, 245 Eulji Ro, Seoul 04564, South Korea
[4] Sungkyunkwan Univ, Dept Internal Med, Div Rheumatol, Sch Med,Samsung Med Ctr, 81 Irwon Ro, Seoul 06351, South Korea