1. Department of Rheumatology, Hanyang University Hospital for Rheumatic Diseases, Seoul, Korea.
2. Hanyang University Institute for Rheumatology Research, Seoul, Korea.
3. Department of Statistics, Kyungpook National University, Daegu, Korea.
4. College of Pharmacy, Chung-Ang University, Seoul, Korea.
5. Department of Information Statistics, Andong National University, Andong, Korea.