OP0020 Assessment of 3-month changes in bone microstructure under anti-tnfα therapy in patients with rheumatoid arthritis using hr-pqct

Background Bone erosions are usually thought to be irreversible and occur in the first few months of RA onset. With its resolution of up to 81 μm, HR-pQCT has emerged as valuable tool to assess bone changes in RA(1,2). Although one previous study showed minimal erosive progression in patients with RA one year after TNFα inhibition therapy (3), no studies have investigated yet the very early bone changes after the initiation of anti-TNFα treatment. Objectives To investigate the early changes in bone erosion progression and bone microarchitecture in the MCP joints and wrist of RA patients using HR-pQCT, radiographs, and 3T MRI after 3 months of anti-TNFα treatment. Methods 26 RA patients underwent 3T MRI wrist scans and HR-pQCT scans of the MCP and wrist joints at baseline (BL) and at 3 months (3M). Radiographs were obtained at the baseline time point only. DAS28 was assessed at BL and 3M. Patients were divided into two groups: the anti-TNFα group and the MTX-only group.HR-pQCT-derived erosion volume, joint volume/width and bone microarchitectural parameters were computed using methods previously developed(4–6), and the joint destruction was assessed via Sharp and RAMRIS scorings using radiographs and MR images respectively. Results Patients in the Anti-TNFα group were slightly younger than patients in the MTX only group and had a higher initial DAS28 score,but otherwise displayed similar anthropometerics and demographics (Table). DAS scores significantly improved in the anti-TNFα group from BL to 3M (Fig. A). 75 erosions were identified at BL by HR-pQCT. The anti-TNFα group showed a significant decrease of erosion volume from BL to 3M at MCH3 (with decreasing trend at MCH2 and wrist). The MTX-only group in contrast, displayed significant increases in erosion volume at MCH2 and wrist despite low disease activity (Fig. B). In the anti-TNFα group, joint space width and volume of the MCP joints decreased significantly from BL to 3M and were positively correlated with erosion volume changes. Although microstructural parameters at the wrist and MCP remained largely unchanged, erosion volume changes were significantly negatively correlated with changes of trabecular BMD in the anti-TNFα group (Fig. C). No significant correlations were observed between HR-pQCT parameters and RAMRIS and DAS scores. Conclusions We found that anti-TNFα treatment can prevent erosion progression and deterioration of bone microarchitecture within the first 3 months of treatment. HR-pQCT can serve as a sensitive and powerful tool to quantify bone changes and monitor RA treatment even over short time periods. References Barnabe C et al. Nat Rev Rheumatol. 2015. Tam LS et al. J Rheumatol. 2016. Moller U et al. Ann Rheum Dis. 2009. Srikhum W et al. J Rheumatol. 2013. Yang H et al. Int J Rheum Dis. 2015. Burghardt AJ et al. Ann Biomed Eng. 2013. Acknowledgements The study was supported by UCB Pharma Inc. Disclosure of Interest None declared