AB1148 THE RELATION ANALYSIS OF BONE MICROARCHITECTURE EVALUATED BY HR-PQCT, AND SYNOVITIS, BONE DESTRUCTION, SYSTEMIC OSTEOPOROSIS IN RHEUMATOID ARTHRITIS
Authors: Naoki Iwamoto, Konosuke Watanabe, Tomohiro Koga, Shin-Ya Kawashiri, Kunihiro Ichinose, Mami Tamai, Hideki Nakamura, Nozomi Ohki, Ko Chiba, Tomoki Origuchi, Makoto Osaki, Atsushi Kawakami
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Periarticular osteoporosis is one of hallmark of rheumatoid arthritis (RA). However, until now the periarticular bone structure including bone mineral density have not been fully elucidated. High-resolution peripheral quantitative computed tomography (HR-pQCT) is a new technique with high spatial resolution that enables us to assess microarchitecture of cancellous and cortical bones that cannot be assessed by conventional X-ray examinations. Recently, few studies using HR-pQCT revealed that bone microarchitecture such as trabecular volumetric densities (Tb.vBMD) were different between RA and non-RA<sup>1</sup>, but these study had not compared findings of HR-pQCT with synovitis assessed by ultrasonography(US) or systemic osteoporosis. <h3>Objectives</h3> To investigate bone microarchitecture evaluated by HR-pQCT in RA. <h3>Methods</h3> This study included 21 RA patient. HR-pQCT imaging analyses quantified bone microarchitecture in 2,3 Metacarpal Head. We measured the bone mineral density (BMD) of lumber spine and femoral neck using Dual-Energy X-ray Absorptiometry (DXA). Synovitis and bone destruction were assessed by US and X-ray, respectively. <h3>Results</h3> Disease duration, age and disease activity were not correlated with bone microarchitecture. BMD of femoral neck was correlated with Tb.vBMD (r=0.84,p&lt;0.01). The joints with US-proven active synovitis [power doppler score (PD)≥2)] showed less Tb.vBMD, trabecular number (Tb.N) and trabecular thickness (Tb.Th) as compared with the patients with US-PD&lt;2 synovitis (Tb.vBMD:121.5 mg/cm<sup>3</sup> vs 145.3 mg/cm<sup>3</sup>, Figure 1). These tendencies were also shown in deferent Metacarpal Heads in the same patient (the mean difference of Tb.vBMD, PD≥2 – PD&lt;2: -11.9 mg/cm<sup>3</sup>). Moreover, the joints with progressive joint destruction as classified by more than steinbrocker stage 3 showed less Tb.vBMD (122.1 mg/cm<sup>3</sup> vs 150.0 mg/cm<sup>3</sup>). The longitudinal analysis of 10 patients revealed that Tb.vBMD and TB.N were improved along with improvement of disease activity (⊿DAS -2.80: from baseline to 12 months after new treatment initiated), but Tb.Th was not improved. <h3>Conclusion</h3> This study revealed that bone destruction and synovitis were associated with bone microarchitecture and, the difference of treatment response by parameter of bone microarchitecture. However, this study was mainly transverse analysis and small samples, we need longitudinal analysis using larger samples. <h3>References</h3> [1] Feehan LM, Li LL, McKay HA. Micro-structural bone changes in early rheumatoid arthritis persist over 1-year despite use of disease modifying anti-rheumatic drug therapy. BMC Musculoskelet Disord 2017; 18(1): 521. <h3>Disclosure of Interests</h3> Naoki Iwamoto: None declared, Konosuke Watanabe: None declared, Tomohiro Koga: None declared, Shin-ya Kawashiri: None declared, Kunihiro Ichinose: None declared, Mami Tamai: None declared, Hideki Nakamura: None declared, Nozomi Ohki: None declared, Ko Chiba: None declared, Tomoki Origuchi: None declared, Makoto Osaki: None declared, Atsushi Kawakami Grant/research support from: Astellas Pharma, Consultant for: Astellas Pharma, Speakers bureau: Astellas Pharma