SAT0364 EFFECT OF ACHIEVING DAPSA-LDA ON THE PROGRESSION OF BONE EROSION AND ENTHESIOPHYTES IN PATIENTS WITH PSORIATIC ARTHRITIS: A LONGITUDINAL HR-PQCT STUDY
Authors: WU Dongze, James F. Griffith, Steven H.M. Lam, Priscilla C. Wong, Lin Shi, Edmund K. LI, Isaac T. Cheng, K. LI Tena, Vivian W. Hung, Ling Qin, Lai-Shan Tam
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Psoriatic arthritis (PsA) is characterized by structural bone damage with bone erosions and enthesiophytes. Whether achieving low disease activity (LDA) according to Disease Activity in PSoriatic <b>Arthritis (</b>DAPSA-LDA) limits progression of structural bone damage, as assessed by high resolution-peripheral quantitative computed tomography (HR-pQCT), is uncertain. <h3>Objectives:</h3> To investigate the progression of structural bone abnormalities at the metacarpal head in patients with PsA over a 5-year period. <h3>Methods:</h3> HR-pQCT examination was were performed in 60 PsA patients at baseline and after 5 years. Baseline-indexed image registration and slice matching were performed to acquire precisely matched baseline and follow-up volumes of interest (VOI) at the 2nd and 3rd metacarpal heads (MCH2 &amp; 3). A semi-automated method was used to calculate bone erosion and enthesiophyte volume [1]. Erosion and enthesiophyte progression was defined as change exceeding the smallest detectable change (SDC). The primary objective of this study was to investigate the degree of bone erosion and enthesiophyte progression in PsA patients receiving routine care. Secondary objectives were to compare changes in bone erosion and enthesiophyte volume between patients who 1) received (TNFi group) or did not receive TNF inhibitor (non-TNFi group); 2) achieved or did not achieve sustained DAPSA-LDA(sDAPSA-LDA) at both baseline and 5-year. <h3>Results:</h3> A total of 108 bone erosions and 99 enthesiophytes were detected at baseline. Three new bone erosions and no new enthesiophytes were evident at 5 years. Mean (±SD) individual bone erosion (4.23±4.15 mm<sup>3</sup>) and enthesiophyte (3.39±2.30 mm<sup>3</sup>) volume at baseline increased significantly (0.58±1.50 mm<sup>3</sup>, p&lt;0.001 for bone erosion; 0.47±0.76 mm<sup>3</sup>, p&lt;0.001 for enthesiophyte volume) over a 5-year period despite disease modifying anti-rheumatic drug being used in 88.3% of patients (Figure 1). The total bone erosion (7.83±7.41 mm<sup>3</sup>) and enthesiophyte volume (5.59±5.46 mm<sup>3</sup>) per patient also increased by 1.07±2.16 mm<sup>3</sup> (p&lt;0.001) and 0.78±1.11 mm<sup>3</sup> (p= 0.001) respectively. 14 patients received TNFi throughout the 5-year period. Comparable changes in bone erosion and enthesiophyte volume were found between the TNFi and the non-TNFi groups. After 5 years, 26 (43%) patients achieved sDAPSA-LDA. Less erosion progression (12/51 [23.5%] vs 25/60 [41.7%], P=0.047) was observed those who did rather than did not achieve sDAPSA-LDA. Similarly, enthesiophyte volume change (0.28±0.67 vs 0.61±0.80 mm<sup>3</sup>; P=0.048) and total enthesiophyte volume change (0.42±0.69 vs 1.05±1.29 mm<sup>3</sup>; P=0.019) were lower in those who did rather than did not achieve sDAPSA-LDA. <h3>Conclusion:</h3> Once DAPSA-LDA is achieved, it should be maintained for a long period so as to minimize progression of structural bone damage in patients with PsA. <h3>Reference</h3> [1] EULAR 2018 (OP0132) &amp; ACR 2018 (865) <h3>Disclosure of Interests:</h3> None declared