1. Division of Rheumatology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
2. Division of Rheumatology, Department of Internal Medicine, Hanyang University Guri Hospital, Guri, Korea.
3. Hanyang University Institute for Rheumatology Research, Seoul, Korea.
4. Biostatistical Consulting and Research Lab, Medical Research Collaborating Center, Hanyang University, Seoul, Korea.