1. Department of Rheumatology, Hanyang University Hospital for Rheumatic Diseases, Seoul, Korea.
2. Department of Internal Medicine, Yonsei Unversity College of Medicine, Seoul, Korea.
3. Department of Rheumatology, Ajou University Hospital, Suwon, Korea.
4. Division of Rheumatology, Daejeon Rheumatoid & Degenerative Arthritis Center, Chungnam National University, Daejeon, Korea.
5. Division of Rheumatology, Department of Internal Medicine, Korea University Anam Hospital, Seoul, Korea.
6. Division of Rheumatology, Department of Internal Medicine, Ewha Womans University Mokdong Hospital, Seoul, Korea.
7. Division of Rheumatology, Department of Medicine, Sungkyunkwan University, School of Medicine, Samsung Medical Center, Seoul, Korea.