Risk Factors for the Reduction of Bone Mineral Density in Patients with Rheumatoid Arthritis Treated With or Without Biologic Disease-Modifying Anti-Rheumatic Drugs

Abstract

Objective: The aim of this study was to identify specific factors associated with reduced bone mineral density (BMD) of the lumbar spine and femoral neck in patients with rheumatoid arthritis (RA) treated with disease-modifying anti-rheumatic drugs (DMARDs), which were either conventional (cDMARDs) alone or biologic (bDMARDs), after the latter medications were approved for use in Japan.

Methods: Ninety-one patients were treated with bDMARDs and 61 with cDMARDs, respectively. We examined factors associated with BMD loss in the lumbar spine and femoral neck. The percentage of least significant change (LSC) was used as the criterion to identify BMD reduction. LSC≥2.4% indicated lumbar BMD reduction, and LSC≥1.9% indicated femoral neck BMD reduction.

Results: Although the average Disease Activity Score 28-C-reactive protein values were 2.3 and 2.5 in the cDMARDs and bDMARDs groups, respectively, more than one-third of patients in both groups (40.9% and 38.5%, respectively) had LSCs of BMD in the femoral neck. Multivariate stepwise binomial logistic regression analysis revealed no statistically significant risk factors for LSC indicating reduced BMD in the cDMARDs group. In contrast, multivariate stepwise binomial logistic regression analysis showed that lack of anti-osteoporosis drug therapy was a risk factor for the LSC, indicating reduced BMD in the lumbar spine in the bDMARDs group. Multivariate logistic regression analysis also showed that the lack of anti-osteoporosis drug therapy and low body mass index were risk factors for the LSC of BMD of the femoral neck in the bDMARDs group.

Conclusion: Although treatment with bDMARDs and cDMARDs achieved successful control of disease activity, the femoral neck BMD continued to decrease. Thus, it is important to start anti-osteoporosis drug treatment before progression of bone loss becomes apparent in patients undergoing bDMARDs treatment.