High prevalence of subclinical salivary gland ultrasound abnormalities in systemic lupus erythematosus: implications for the diagnosis of secondary Sjögren’s syndrome

Abstract Introduction Secondary Sjögren’s syndrome (sSS) is a common overlap condition in patients with systemic lupus erythematosus (SLE), frequently contributing to morbidity and impaired quality of life. However, its diagnosis remains challenging due to the reliance on invasive or resource-intensive diagnostic procedures. The aim of this work is to assess the diagnostic value of salivary gland ultrasonography (SGUS) in detecting secondary Sjögren’s syndrome among patients with systemic lupus erythematosus. Methods This cross-sectional study included a total of 35 individuals diagnosed with SLE. Patients were classified as having probable secondary Sjögren’s syndrome using a clinically adapted approach informed by the 2016 ACR/EULAR classification framework. All participants underwent SGUS, with the imaging results evaluated and scored based on the validated OMERACT scoring system. A full clinical and laboratory assessment for SLE was also carried out. Results The presence of sSS was determined in 23 patients (65.71%). Twenty-two individuals (62.85%) of the total cohort demonstrated pathological SGUS findings (score ≥ 2). However, there were no significant differences in SGUS OMERACT scores between SLE patients with and without sSS (3.08 ± 1.04 vs. 2.91 ± 0.99, p = 0.66). Pathological SGUS changes were observed in 65.2% of the sSS group compared to 58.3% in the non-sSS group ( p = 0.68). Consequently, the ROC curve analysis yielded a low area under the curve (AUC) of 0.54, indicating that SGUS scores could not reliably distinguish between sSS and SLE-associated subclinical sialadenitis in this cohort. Conclusion While salivary gland ultrasound abnormalities are highly prevalent in patients with systemic lupus erythematosus, they demonstrate limited specificity for diagnosing secondary Sjögren’s syndrome due to the high frequency of subclinical glandular involvement in SLE. SGUS should be interpreted with caution as a standalone diagnostic tool for sSS in this population.