The clinical and immunological characteristics related to salivary gland enlargement in primary Sjogren's syndrome: a retrospective cross-sectional study

Background: Salivary gland enlargement (SGE) is one of the common manifestations in primary Sjogren's syndrome (pSS) patients who are first referred to the hospital of stomatology. Whether the characteristics of the pSS patients with SGE differ from those of the ones without SGE remains unclear. Therefore, this study aimed at investigating the clinical and immunological characteristics related to SGE in pSS, to provide a comprehensive understanding of the clinical phenotype of pSS with SGE.Methods: In this retrospective cross-sectional study, medical records of patients diagnosed with pSS from 2016 to 2021 were evaluated. The included patients were divided into the SGE and non-SGE groups. Patient data including general clinical data, radiographic and B-ultrasound examination data, and immunological data were extracted. Intergroup differences were analyzed using the chi-square test, Fisher's exact test, and non-parametric tests with SPSS 23.0. Binary logistic regression analysis was further performed to determine the factors related to SGE in pSS.Results: Two hundred and three patients with pSS were included, including 126 and 77 patients with and without SGE, respectively. Univariate analysis showed that compared to the non-SGE group, the SGE group was younger, had dry eye symptom for a longer duration, and had a higher proportion of patients with severe conditions on salivary gland radiography (P<0.05). Regarding immunological indicators, the levels of anti-Ro52, anti-SSA (Ro60), and anti-SSB antibodies; immunoglobulin (Ig)G; IgA; and rheumatoid factor (RF) and erythrocyte sedimentation rate (ESR) were significantly higher in the SGE group (P<0.05). Binary logistic regression analysis showed that younger age and high anti-Ro52 levels were independent factors related to SGE in pSS.Conclusions: SGE is highly consistent with increased immunological indicators, reflecting disease activity. pSS patients with SGE were younger than those without. Special attention should be paid to the changes in the anti-Ro52 level since it is an independent factor related to SGE in pSS.