Rheumatoid arthritis is associated with less optimal hip structural geometry

Impact of Bone Mineral Density and Bone Structural Properties on Postmenopausal Women With Rheumatoid Arthritis in Japan: A Cross-Sectional Study

Introduction There has been no study on bone structural properties in postmenopausal women with rheumatoid arthritis (RA) in Japan. This study investigated bone mineral density (BMD) and bone structural properties in Japanese postmenopausal women with RA. Methods The study had a cross-sectional design and included 119 postmenopausal women aged 50-80 years with RA symptoms for more than five years. BMD, trabecular bone score (TBS), and results of hip structure analysis (HSA) were measured on dual-energy X-ray absorptiometry scans. The control group consisted of 288 women aged 50-80 years without RA. The RA group and control group using bisphosphonates were compared after propensity score matching for age, body mass index, and fracture history. Women in the RA group were also compared according to the use of glucocorticoids (GCs). Results After the propensity matching score, there were no other significant differences in BMD, TBS, and HSA parameters between the RA group and the control group. In the RA group, the TBS was lower in patients on GCs than those not on GCs (1.272 vs 1.313, p=0.008). There were no other significant differences in BMD and HSA parameters between patients in the RA group according to the use of GCs. Conclusion Although there were no differences in BMD, the TBS was lower in patients on GCs than those not on GCs in the RA group. It is thus important for physicians who administer GCs to treat patients with RA to be aware of not only BMD but also TBS.

Impact of Anti-Citrullinated Protein Antibodies on Progressive Systemic Bone Mineral Density Loss in Patients With Early Rheumatoid Arthritis After Two Years of Treat-to-Target

Objectives

To investigate the association of anti-citrullinated protein antibodies (ACPA) with changes in systemic bone mineral density (BMD) in patients with early rheumatoid arthritis (RA) after two years of treat-to-target.

Methods

BMD was measured at the lumbar spine (LS) and femoral neck (FN) in 100 patients with recent onset RA at baseline and after 24 months of treatment aimed at low disease activity (LDA) according to the 28-joints disease activity score (DAS28 <3.2). Multivariable regression analyses were performed to determine independent associations between autoantibodies and other disease and treatment-related parameters with BMD loss.

Results

After 24 months, the majority of the patients were at least in LDA (78%), with slightly more ACPA-positive subjects achieving the target. The BMD had significantly decreased at both the LS (mean [SD] percent loss -1.8 [6.2], p=0.03) and the FN (-2.4 [7.3], p=0.03) in ACPA-positive but not in ACPA-negative patients. Consequently, the proportion of patients with reduced BMD (Z score ≤-1) after 24 months was significantly higher among ACPA-positive patients at both the spine (39.5% vs 19.3%, p=0.05) and the hip (37.2% vs 12.2%, p=0.007). The association between ACPA and BMD loss was independent of other variables including age, gender, disease activity, cumulative dose of glucocorticoids and duration of therapy with bisphosphonates at the LS but not the FN.

Conclusions

ACPA are associated with ongoing BMD loss at the spine despite suppression of inflammation and adoption of prophylactic measures. ACPA-positive RA patients should be therefore strictly monitored for the development of osteoporosis.

Beyond Bone Mineral Density: A New Dual X-Ray Absorptiometry Index of Bone Strength to Predict Fragility Fractures, the Bone Strain Index

For a proper assessment of osteoporotic fragility fracture prediction, all aspects regarding bone mineral density, bone texture, geometry and information about strength are necessary, particularly in endocrinological and rheumatological diseases, where bone quality impairment is relevant. Data regarding bone quantity (density) and, partially, bone quality (structure and geometry) are obtained by the gold standard method of dual X-ray absorptiometry (DXA). Data about bone strength are not yet readily available. To evaluate bone resistance to strain, a new DXA-derived index based on the Finite Element Analysis (FEA) of a greyscale of density distribution measured on spine and femoral scan, namely Bone Strain Index (BSI), has recently been developed. Bone Strain Index includes local information on density distribution, bone geometry and loadings and it differs from bone mineral density (BMD) and other variables of bone quality like trabecular bone score (TBS), which are all based on the quantification of bone mass and distribution averaged over the scanned region. This state of the art review illustrates the methodology of BSI calculation, the findings of its in reproducibility and the preliminary data about its capability to predict fragility fracture and to monitor the follow up of the pharmacological treatment for osteoporosis.