Background:Primary Sjögren’s syndrome (pSS) is a chronic inflammatory autoimmune disease characterized by lymphocyte infiltration in salivary and lacrimal glands. pSS affects primarily middle-aged and elderly patients, although younger age groups may also be involved. However, differences of etiology and pathogenesis between early-onset pSS (EOpSS) and late-onset pSS (LOpSS) are unknown. Recently, standardized outcome tools for measuring disease-specific activity and patients’ reported symptoms have been formulated by the European League Against Rheumatism (EULAR) SS study group: the EULAR SS Disease Activity Index (ESSDAI) for systemic features of pSS [1]. Also, as the new imaging techniques, salivary gland ultrasonography (SGUS) proved valuable for assessing salivary gland involvement in SS and seemed to exhibit good diagnostic properties. In addition, previous studies have demonstrated usefulness of SGUS for the prognostic stratification of patients with pSS [2], [3], [4].Objectives:The aim of this study was to examine the differences of etiology and pathogenesis between EOpSS and LOpSS using ESSDAI and SGUS.Methods:Fifty-six pSS patients who fulfilled the American College of Rheumatology (ACR) / European League Against Rheumatism (EULAR) classification criteria for SS were studied. Based on the disease onset age, all pSS patients were divided into two groups as those with the onset age of 40 years old or younger (EOpSS: n=26) and those with the onset age of older than 65 years old (LOpSS: n=30). The clinical findings were evaluated ESSDAI and OMERACT SGUS score at the first visit to our hospital. The ESSDAI (0–123) proposes the evaluation of 12 domains or organ systems (constitutional, lymphadenopathy, glandular, articular, cutaneous, pulmonary, renal, peripheral nervous system, central nervous system, muscular, hematological and biology). All patients were examined SGUS by a single investigator who was blinded to device (TUS-A300; Canon Medical Systems, Tokyo, Japan) with a linear transducer (7.5-10MHz). The OMERACT SGUS score was used for graded changes in the parenchymal homogeneity of salivary glands: grade 0, normal-appearing salivary gland parenchyma; grade 1, minimal change: mild inhomogeneity without hypo/anechoic areas; grade 2, moderate change: moderate inhomogeneity with focal hypo/anechoic areas; grade 3, severe change: diffuse inhomogeneity with hypo/anechoic areas occupying the entire gland surface [5].Results:The proportions of positive sera of RF, anti-SS-A and anti-SS-B antibodies were not different in the two groups, but the disease activities were higher in the EOpSS than in the LOpSS patients by measuring ESSDAI (7.30 vs 4.23, p=0.008), especially in constitutional domain (1.50 vs 0.60, p=0.03), articular domain (1.54 vs 0.40, p=0.0002) and biological domain (1.35 vs 0.90, p=0.04). No difference in salivary secretion was found between two groups (EOpSS: 8.02 vs LOpSS: 6.31 mL/10min.), but the OMERACT SGUS score was higher in LOpSS than in EOpSS patients (2.00 vs 2.70, p=0.0002).Conclusion:Although serological findings were not different, EOpSS patients had higher disease activity but less severe salivary gland degeneration than that in LOpSS patients, suggesting the pathogenesis of these two groups was different.References:[1]Seror R, et al. Ann Rheum Dis. 2010 Jun;69(6):1103-9.[2]Arthritis Care Res (Hoboken). 2014 Jul;66(7):1102-7.[3]Hammenfors DS, et al. Clin Exp Rheumatol. 2015 Jan-Feb;33(1):56-62.[4]Milic V, et al. PLoS One. 2019 Dec 31;14(12): e0226498.[5]Jousse-Joulin S, et al. Ann Rheum Dis. 2019 Jul;78(7):967-973.Disclosure of Interests:None declared
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