1. Division of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan;
2. Department of Rheumatology, Aomori Prefectural Central Hospital, Aomori, Japan;
3. Department of Internal Medicine, Takikawa Municipal Hospital, Takikawa, Japan;
4. Department of Hematology and Rheumatology, Tohoku University Graduate School of Medicine, Sendai, Japan;
5. Department of Internal Medicine, Tomakomai City Hospital, Tomakomai, Japan;
6. Hokkaido Medical Center for Rheumatic Diseases, Sapporo, Japan;
7. Department of Rheumatology and Orthopaedic Surgery, Hokkaido Orthopaedic Memorial Hospital, Sapporo, Japan;
8. Higashisendai Rheumatic Disease Clinic, Sendai, Japan;
9. Division of Rheumatology, Kin-ikyo Chuo Hospital, Sapporo, Japan;
10. The Center for Rheumatic Diseases, Tonan Hospital, Sapporo, Japan;
11. Izumi Himawari Clinic, Sendai, Japan;
12. NTT Sapporo Medical Center, Sapporo, Japan;
13. Kiyota Hospital, Sapporo, Japan;
14. Faculty of Health Sciences, Hokkaido University, Sapporo, Japan