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Risk Factors Associated with Incident Clinical Vertebral and Nonvertebral Fractures in Japanese Women with Rheumatoid Arthritis: A Prospective 54-month Observational Study
TAKEFUMI FURUYA, SHIGERU KOTAKE, EISUKE INOUE, YUKI NANKE, TORU YAGO, TSUYOSHI KOBASHIGAWA, NAOMI ICHIKAWA, EIICHI TANAKA, SHIGEKI MOMOHARA, AYAKO NAKAJIMA, MASAKO HARA, TAISUKE TOMATSU, HISASHI YAMANAKA, and NAOYUKI KAMATANI ABSTRACT. Objective. To evaluate the association between potential risk factors and incident clinical fractures in Japanese patients with rheumatoid arthritis (RA). Methods. A total of 1733 female patients with RA over age 50 years were enrolled in a prospective observational cohort study. Participants were followed for 54 months from October 2000 to March 2005, and classified into 4 groups according to incident fracture status since baseline: those without a new fracture; those with a new clinically recognized vertebral fracture; those with an incident nonvertebral fracture at the wrist, hip, humerus, pelvis, or ribs (main nonvertebral fracture); and those with any new nonvertebral fracture. Cox proportional hazard models were used to analyze independent contributions of various risk factors to fracture incidence. Results. During the followup period, 33, 34, and 98 patients developed a vertebral, a main nonvertebral, and any nonvertebral fracture, respectively. The Japanese Health Assessment Questionnaire (J-HAQ) score was associated with relative risks (RR) of 2.42 (95% confidence interval 1.42–4.14), 1.76 (95% CI 1.07–2.89), and 1.73 (95% CI 1.29–2.32) for vertebral, main nonvertebral, and all nonvertebral fractures. The risks of vertebral and any nonvertebral fractures were increased for age over 70 years compared with age in the 50s (RR 3.25, 95% CI 1.19–8.86; and RR 2.22, 95% CI 1.20–4.10, respectively). Clinical variables and medications were associated with a new fracture. Conclusion. HAQ, age, history of any prior fracture, and orthopedic surgery for RA appear to be associated with fractures in Japanese women with RA. (First Release Dec 1 2006; J Rheumatol 2007;34:303–10) Key Indexing Terms:
COHORT STUDIES From the Institute of Rheumatology, Tokyo Women's Medical University, Tokyo, Japan. Supported by a research consortium of 36 pharmaceutical companies for the large cohort study of RA at our institute, where multiple parallel research projects are under way. Companies contributed to this consortium dependent on their scientific interest for the entire cohort, but not for a specific research project using this cohort. T. Furuya, MD, PhD, Assistant Professor; S. Kotake, MD, PhD, Assistant Professor; E. Inoue, BEng, Fellow; Y. Nanke, MD, PhD, Assistant Professor; T. Yago, MD, Instructor; T. Kobashigawa, MD, Instructor; N. Ichikawa, MD, PhD, Instructor; E. Tanaka, MD, PhD, Instructor; S. Momohara, MD, PhD, Associate Professor; A. Nakajima, MD, PhD, Assistant Professor; M. Hara, MD, PhD, Professor; T. Tomatsu, MD, PhD, Professor; H. Yamanaka, MD, PhD, Professor; N. Kamatani, MD, PhD, Professor and Chairman, Institute of Rheumatology, Tokyo Women's Medical University. Address reprint requests to Dr. T. Furuya, Institute of Rheumatology, Tokyo Women's Medical University, 10-22 Kawada-cho, Shinjuku-ku, Tokyo 162-0054, Japan. E-mail: furuyat@ior.twmu.ac.jp Accepted for publication October 18, 2006.
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