Background Patients with rheumatoid arthritis (RA) have a high risk of hip fracture. Limited data exist in the literature concerning risk factors for incident hip fractures in patients with RA. Previously,we reported clinical risk factors for both incident vertebral and non-vertebral fractures in Japanese patients with RA (1, 2). However, we did not evaluate the risk factors for hip fractures alone, because in our previous studies, the number of hip fracture patients was small.
Objectives To evaluate the association between potential risk factors and incident hip fractures in Japanese RA patients.
Methods Institute of Rheumatology Rheumatoid Arthritis (IORRA) is a prospective observational cohort study of Japanese RA patients at the Institute of Rheumatology, Tokyo Women’s Medical University (Tokyo, Japan) that was begun in 2000. A total of 9,720 patients (82% female, mean age 56 years) with RA were enrolled in the IORRA cohort study from 2000 to 2010. Self-reported hip fractures were verified with patient medical records. Cox proportional hazards models were used to analyze independent contributions of various risk factors to hip fracture incidence.
Results During a mean (SD) follow-up of 5.2 (3.3) years, 152 patients reported 152 hip fractures. Among these 152 patients, 97 hip fractures in 97 patients (15 males, 82 females) were verified with medical records. Japanese version of the Health Assessment Questionnaire (J-HAQ) disability score (P=1.1×10-12), age (P=2.4×10-6), history of total knee replacement (TKR) (P=0.0076), and body mass index (BMI) (P=0.021) were significantly associated with hip fractures (model (1) in Table). Among the scores on the 8 domains of the J-HAQ, HAQ (arising) (P=7.0×10-5) and HAQ (hygiene) (P=0.0076) were significantly correlated to incident hip fractures (model (2) in Table). While inconclusive, past fracture history appeared to be associated with hip fracture risk (model (1) and (2) in Table). We did not find significant associations of incident hip fractures with gender, smoking, RA duration, the Disease Activity Score in 28 joints, visual analog scale (VAS) for pain, VAS by physician, daily prednisone dose, weekly methotrexate dose, bisphosphonate use, active vitamin D3 use, biologic use, folic acid use, or proton pump inhibitor use.
Conclusions High HAQ disability score, old age, history of TKR, and low BMI appear to be associated with incident hip fractures in Japanese patients with RA. Among the 8 domains of the J-HAQ, disabilities of arising and hygiene appear to correlate to incident hip fractures in Japanese RA patients.
Furuya T, et al. J Rheumatol (2007) 34:303-310,
Furuya T, et al. J Bone Miner Metab (2008) 26:499-505.
Disclosure of Interest T. Furuya: None Declared, E. Inoue: None Declared, T. Hosoi: None Declared, A. Taniguchi: None Declared, S. Momohara: None Declared, H. Yamanaka Grant/Research support from: IORRA study is supported by 40 pharmaceutical companies;Asahikasei Kuraray Medical Co.,Ltd. Abbott Japan Co.,Ltd. Asahikasei Pharma Corporation Astellas harma Inc. AstraZeneca K.K. Bristol-Myers Squibb Chugai Pharmaceutical Co.,Ltd. Daiichi Fine Chemical Co.,Ltd. Daiichi Sankyo Co.,Ltd. Dainippon Sumitomo Pharma Co.,Ltd. Eisai Co.,Ltd. GlaxoSmithKline K.K. Hisamitsu Pharmaceutical Co.,Inc. Janssen Pharmaceutical K.K. Japan Tobacco Inc. Kaken Pharmaceutical Co.,Ltd. Kissei Pharmaceutical Co., Ltd. Kowa Pharmaceutical Co.Ltd. Maruho Co.,Ltd. Mitsubishi Chemical Medience Corporation Mitsubishi Tanabe Pharma Corporation Mochida Pharmaceutical Co., Ltd. MSD K.K., Mundipharma K.K. Nippon Chemiphar Co.,Ltd. Nippon Shinyaku Co.,Ltd. Novartis Pharma K.K. Otsuka Pharmaceutical Co.,Ltd. Pfizer Japan Inc. Sanofi-Aventis K.K. Santen Pharmaceutical Co.,Ltd. Sanwa Kagaku Kenkyusho Co.,Ltd. Sekisui Medical Co.,Ltd. Shionogi Co.,Ltd. Taishotoyama Pharmaceutical Co.,Ltd. Takeda Pharmaceutical Company Limited Teijin Pharma Limited Torii Pharmaceutical Co.,Ltd. UCB Japan Co. Ltd. ZERIA Pharmaceutical Co.,Ltd., Consultant for: Abbott, AstraZeneca, Bristol-Myers Squibb, Chugai, Eisai, Janssen, Mitsubishi Tanabe., Pfizer, Takeda, Teijin Pharma, UCB