Background Patients with rheumatoid arthritis (RA) show problems with bone metabolism. The bone mineral density (BMD) of patients with RA is lower than that of healthy individuals. Biologic agents and bisphosphonates are both effective against osteoporosis in patients with RA1, and control of disease activity in RA is also important for osteoporosis; however, which is most important for osteoporosis in patients with RA remains unclear. Change in BMD (ΔBMD) represents a useful parameter for determining improvements in osteoporosis and bone metabolism.
Objectives We investigated ΔBMD in patients with RA and healthy individuals. Factors predicting ΔBMD were analyzed in patients with RA.
Methods We started the 10-year prospective cohort TOMORROW (TOtal Management Of Risk factors in Rheumatoid arthritis patients to lOWer morbidity and mortality clinical trial; registration number, UMIN000003876) in 2010. BMD was measured at three points (whole body, lower limb, lumbar spine) for age- and sex-matched patients with RA and healthy individuals using dual-energy X-ray absorptiometry (DXA). We compared ΔBMD in both groups between 2010 and 2013. Predictive factors for ΔBMD in RA were investigated by univariate analysis, and the importance of biologic agents, bisphosphonates, and control of disease activity in RA were compared.
Results Participants comprised 192 patients with RA and 194 healthy individuals. Clinical data from 2013 are shown in Table 1. The ΔBMD of patients with RA was -0.2% (whole body), -0.1% (lower limb), and 3.1% (lumbar spine), while that of healthy individuals was 0.4% (whole body), -0.1% (lower limb), and 2.2% (lumbar spine). No significant differences in ΔBMD for whole body or lower limb were seen; however, ΔBMD of the lumbar spine was significantly increased in both groups (p<0.0001). No significant differences between groups were identified. In patients with RA, ΔBMD of the lumbar spine was significantly higher in bisphosphonate users than in non-bisphosphonate users (6.2% vs. 1.8%, p=0.0001). Changes in disease activity and use of biologic agents did not influence ΔBMD (p=0.1368 and p=0.1117, respectively).
Conclusions Increased lumbar BMD appeared to reflect degenerative changes in the lumbar spine. Bisphosphonate use was a more important influence on ΔBMD than changes in disease activity or use of biologic agents in patients with RA. BMD might thus degenerate even when disease activity is under good control using biologic agents. Bisphosphonates are important for protecting against the development of osteoporosis and improving bone metabolism in patients with RA.
Lange U, et al. Increase in bone mineral density of patients with rheumatoid arthritis treated with anti-TNF-alpha antibody: a prospective open-label pilot study. Rheumatology (Oxford). 2005; 44:1546-8.
Disclosure of Interest M. Tada: None declared, T. Koike Grant/research support: Grant/research support: Takeda Pharmaceutical, Mitsubishi Tanabe Pharma Corporation, Chugai Pharmaceutical, Eisai, Abbott Japan, Teijin Pharma, Banyu Pharmaceutical and Ono Pharmaceutical, K. Inui Grant/research support: Chugai Pharmaceutical Co., Ltd., Mitsubishi Tanabe Pharma Co., Astellas Pharma Inc., Abbvie GK, Eisai Co.,Ltd., MSD K.K., Speakers bureau: Bristol-Myers K.K., Takeda Pharmaceutical Corporation, Ltd., Chugai Pharmaceutical Co., Ltd., Janssen Pharmaceutical K.K., Abbvie GK,Astellas Pharma Inc., Y. Sugioka: None declared, K. Mamoto: None declared, T. Okano: None declared, H. Nakamura Grant/research support: Chugai Pharmaceutical Co., Ltd., Astellas Pharma Inc., Nippon Zoki Pharmaceutical Co., Ltd., Daiichi Sankyo, Speakers bureau: Eisai Co., Ltd., Daiichi Sankyo