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