FRI0560 Comparison of Bone Microstructure of Psoriatic Arthritis and Psoriasis Patients – An HR-PQCT Study of Anabolic and Catabolic Bone Changes
Authors: D. Simon, F. Faustini, M. Englbrecht, A. Kleyer, R. Kocijan, J. Haschka, C. Figueiredo, S. Kraus, A.J. Hueber, M. Sticherling, G. Schett, J. Rech
Journal: Annals of the Rheumatic Diseases (2015)

<h3>Background</h3> Psoriatic disease comprises psoriatic arthritis (PsA), cutaneous psoriasis (PSO) and psoriatic nail disease.<sup>1</sup>PsA shows both bone erosion and proliferation. However, the latter seems to be present in PSO even in absence of joint manifestations.<sup>2</sup> <h3>Objectives</h3> (I) To compare the bone microstructure in PSO patients, without signs and symptoms of PsA, and in PsA patients and (II) to investigate whether specific demographic and clinical variables accompany bone changes. <h3>Methods</h3> Prospective cross-sectional study based on high-resolution peripheral quantitative computed tomography (HR-pQCT) examination of the metacarpal head and phalangeal base of the MCP joints 2 and 3 of the dominant hand. We assessed erosions and enthesiophytes by frequency, volume (for erosions, mm<sup>3</sup>) and size (for enthesiophytes, mm). Erosions were defined as breaks in the cortical shell within the joint visible in two planes, enthesiophytes as bony protrusions emerging from the cortical shell in the periarticular region. The study was approved by the local ethic committee, and the National Radiation Safety Agency (BfS). Patients signed consent. <h3>Results</h3> 101 PsA patients (mean age 50.8±13.2 years, N=51 female) and 55 PSO patients (49.0±11.4, N=20 female) were included. Mean age and sex distribution were comparable. In the PsA group skin disease duration was 18.9±14.8 years, joint disease duration was 6.4±7.3 years. Mean PASI score was 3.4±5.5 with 20.8% of the PsA patients showing nail and 19.8% scalp involvement. PSO patients mean disease duration was 15.2±15.4 years, PASI score 6.2±8.0. Nail disease was present in 50.9%, scalp involvement in 29.1%. 52 PsA patients were treated with conventional DMARDs, 49 with biological DMARDs. 140 erosions were identified in the PsA group and 27 in the PSO group (mean ± SD/patient: 1.39±2.16 (PsA) vs. 0.49±0.94 (PSO); <i>p</i>=0.002, U=2023.5). Erosions mean volume differed between the groups, with the PsA patients showing larger lesions (6.29±9.71 mm<sup>3</sup> vs. 3.29±3.09 mm<sup>3</sup>, <i>p</i>=0.003, U=2005.0). PsA patients showed a higher number of enthesiophytes (963 vs. 306), which accounted for a statistically significant difference in mean number per patient (mean ± SD/patient: 9.53±6.66 vs. 5.62±3.30, <i>p</i>≤0,001, U=1468.5). Additionally, enthesiophytes were larger in PsA compared to PSO patients (Fig. 1 A,B). Mean enthesiophyte size was 6.79±5.62 mm in the PsA group and 4.01±2.19 mm in the PSO group (<i>p</i>≤0.001, U=1722.0). With respect to PSO and PsA patients, two linear regression models investigating the role of age, sex, PASI score, BMI, and duration of psoriasis showed that only the duration of psoriasis is independently and positively related to the number of erosions and enthesiophytes (b<sub>ero.</sub>=0.23, <i>p</i>=0.031; b<sub>enthe.</sub>=0.24, <i>p</i>=0.023). <h3>Conclusions</h3> HR-pQCT analysis of the bone microstructure of PsA and PSO subjects indicates that PsA patients show significant more anabolic and catabolic bone changes. Duration of skin disease seems to play a decisive role for pathologic changes of the periarticular bone microstructure of psoriatic patients. <h3>References</h3> Scarpa R, et al. J Rheumatol 2006;33:210-2. Simon D, et al. Ann Rheum Dis 2014;73(Suppl 2):464-5. <h3>Disclosure of Interest</h3> None declared