SAT0431 The acr-eular classification criteria in primary sjÖgren’s syndrome: the contributing role of ultrasound
Authors: E. Mossel, J.F. van Nimwegen, M.S. van Ginkel, K. Delli, A.J. Stel, F.G. Kroese, F.K. Spijkervet, A. Vissink, S. Arends, H. Bootsma
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Salivary gland ultrasound (SGUS) is cheap, non-invasive and easy to perform in an outpatient setting. The ACR-EULAR criteria were recently developed to reach international consensus regarding the classification of primary Sjögren's syndrome (pSS), but SGUS is not yet included as a classification item. <h3>Objectives</h3> To assess the performance of the ACR-EULAR criteria when salivary gland ultrasound (SGUS) replaces current items, in a large cohort of patients clinically suspected or diagnosed with pSS in daily clinical practice. <h3>Methods</h3> Included were all consecutive outpatients who underwent SGUS between October 2014 and , July 2017 and had a complete data-set on all ACR-EULAR items. Classification according to the criteria was determined separately in patients who were subjected to a labial or parotid gland biopsy. For SGUS, the average score for hypoechogenic areas in the parotid and submandibular glands on one side was applied (range 0–3)<sup>1</sup>. The optimal cut-off value for our SGUS score was determined using ROC analysis. Clinical diagnosis by the treating physician was used as gold standard. Area under the curve (AUC), absolute agreement, sensitivity and specificity of the original and adjusted ACR-EULAR criteria sets were determined. <h3>Results</h3> Of the 363 consecutive patients, 243 patients had a complete data-set, of whom 147 patients were diagnosed with pSS. Accuracy of SGUS to predict clinical diagnosis was good, with an AUC of 0.860 and optimal cut-off value of ≥1.5. When applying a weight of 1 point for a positive SGUS, the cut-off value of the ACR-EULAR criteria to discriminate between pSS and non-pSS remained 4, irrespective of the type of biopsy used. In patients who underwent a labial gland biopsy (n=124), the original ACR-EULAR criteria showed an AUC of 0.965 (figure 1A). Absolute agreement with clinical diagnosis was 94.4%, sensitivity was 95.9% and specificity was 92.2%. When SGUS replaced the labial gland biopsy, absolute agreement was 87.9%, sensitivity was 82.2% and specificity was 96.1%. When SGUS replaced anti-SSA antibody status, absolute agreement was 89.5%, sensitivity was 86.3% and specificity was 94.1%. When SGUS replaced the ocular staining score (OSS), Schirmer's test or unstimulated whole saliva flow (UWS), absolute agreement varied between 89.5%–93.5%, sensitivity varied between 90.4%–95.9% and specificity varied between 88.2%–92.2%. In patients who underwent a parotid gland biopsy (n=198), similar results were found (figure 1B). <h3>Conclusions</h3> SGUS cannot be used as a replacement for salivary gland biopsy or anti-SSA antibody status in the ACR-EULAR criteria because of a substantial reduction in sensitivity. For diagnostic purposes, a high sensitivity is preferred over a high specificity. Replacement of the OSS, Schirmer's test or UWS by SGUS only resulted in negligible changes in accuracy of the ACR-EULAR criteria. With SGUS being able to replace one of these function tests, clinicians are offered more options that could lead to fulfilment of the ACR-EULAR criteria. <h3>Reference</h3> [1] Mossel, et al. Ann Rheum Dis2017: Published online first at December 12. <h3>Disclosure of Interest</h3> None declared