POS1066 IS ENTHESITIS A SONOGRAPHIC BIOMARKER OF DISEASE SEVERITY IN PSORIATIC ARTHRITIS? THE LINK BETWEEN ULTRASOUND ENTHESEAL ABNORMALITIES AND PERIPHERAL JOINT EROSIVE DAMAGE

Abstract

Background:Enthesitis is one of the hallmark of psoriatic arthritis (PsA). Ultrasound (US) accurately detects morphostructural abnormalities indicative of entheseal inflammation and structural damage. Interestingly, in a recent study, US-detected entheseal pathology appeared to be a potential marker of disease severity, being associated with higher radiographic score of structural damage at peripheral joint level. (1) However, a sub-analysis of the impact of each elementary finding of US enthesitis was not performed. Moreover, some US entheseal abnormalities (hypoechogenicity, thickening and calcification/enthesophyte) have been described as frequent findings in healthy subjects and patients with dysmetabolic conditions, undermining their specificity. (2) Thus, we hypothesized that their role as a sonographic biomarker of joint disease severity could be questioned.Objectives:The main aim of the present study was to explore the association between the US elementary findings of enthesitis defined by OMERACT [i.e. hypoechogenicity, thickening, Doppler signal, calcification/enthesophyte and bone erosion at enthesis] (3) and the presence of US-detected joint bone erosions in patients with PsA.Methods:Consecutive patients with PsA (CASPAR criteria) were included in this cross-sectional single-centre study. The scanning protocol included bilateral assessment of the main entheses of the lower limbs [plantar fascia, quadriceps, patellar (proximal and distal) and Achilles tendons]. The presence of US joint bone erosions was investigated in the following areas: 2nd and 5th metacarpophalangeal (MCP) joints, ulnar head and 5th metatarsophalangeal (MTP) joint, bilaterally, as well as the most inflamed joint at the physical examination. The US examination was carried out with a 6-18 MHz probe. Univariate and multivariate logistic analysis were performed to identify predictors of US joint bone erosions.Results:A total of 74 PsA patients were enrolled. The mean disease duration was 7.9±8.0 years. Joint bone erosions were found in 36/75 patients (48.0%), and in 71/600 joints (11.8%), most frequently in the 5th MTP joint (in 26/75 patients, 34.7%). The univariate analysis showed that entheseal bone erosions [odds ratio (OR) 27.1, 95% confidence interval (CI) 3.3-220.2, p value <0.01] and Doppler signal (OR 3.5, 95% CI 1.3 - 9.4, p value 0.01) were associated with joint bone erosions. Only entheseal bone erosions remained significantly associated with joint bone erosions in the multivariate analysis (Table 1).Table 1.Multivariate regression analysis: predictive value of the entheseal US findings for the presence of joint bone erosions.OR (95% CI)P valueHypoechogenicity0.5 (0.1-3.4)0.45Thickening2.2 (0.6-8.3)0.27Doppler signal3.2 (0.9-10.8)0.06Calcification/enthesophyte1.1 (0.1-11.2)0.99Entheseal bone erosion24.2 (2.7-216.2)<0.01Conclusion:Entheseal bone erosion and, to a lesser extent, Doppler signal, were the only entheseal abnormalities correlated with the presence of US-detected joint bone erosions, representing potential sonographic biomarkers of disease severity in PsA.