Background/Purpose: Bone erosions and joint space narrowing (JSN) are significant aspects of structural damage in rheumatoid arthritis. High resolution peripheral quantitative computed tomography (HR-pQCT) allows detailed analysis of bone erosion, joint space and bone microstructure. We previously reported bone erosion and microarchitecture evaluation using HR-pQCT within the first three months after the initiation of anti-tumor necrosis factor (TNFα) treatment. However, no study has yet reported if early bone changes such as three months would predict the future changes of bone destruction. Hence, the goal of this study was to quantify erosion volume, bone microarchitecture, joint space volume and width from prior to anti-TNFα therapy to one year after initiation using HR-pQCT, and to investigate if development of erosions at 3-months can predict progression of erosions after 1 year.

Methods: Twenty-one RA patients receiving MTX treatment were recruited and divided into two groups according to disease activity scores (low (DAS28≦3.2) (N=9) and high (DAS28>3.2) (N=12) DAS group). Patients in the high DAS group were treated with anti-TNFα and MTX immediately after the baseline MRI (BL). All patients underwent HR-pQCT scans of the MCP at BL, 3-months (3M) and 1-year (1Y). HR-pQCT-derived erosion volume, joint space volume and width and bone microarchitecture at the MCP2 and MCP3 were measured using in-house developed software with previously reported excellent in-vivo reproducibility.

Results: 37 bone erosions were detected at BL. In the high DAS group, one erosion was full repaired, while two new erosions were observed at 1-year. Although there were no significant changes of mean bone erosion volume in the high DAS group from BL to 1Y, the low DAS group showed increases in mean bone erosion volume from BL to 1Y regardless of lower disease activity (P=0.006). Changes of bone erosion volume from BL to 3M were significantly correlated with changes of bone erosion volume from 3M to 1Y (P=0.001). On the other hand, both groups showed significant joint space narrowing at 1Y compared to BL (P=0.008).

Conclusion: Our findings suggest that early changes in bone erosion volume can predict future disease progression. Therefore, additional treatment may be necessary for patients whose bone erosion volume increases during the early period despite good response for DAS28. HR-pQCT provides sensitive technique to measure erosion progression even within 3-months after treatment.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/bone-erosion-volume-changes-measured-by-hr-pqct-at-3-months-after-initiation-of-anti-tnf-treatment-predicted-erosion-volume-changes-at-1-year-in-ra/