Salivary gland ultrasonography in primary Sjögren’s syndrome from diagnosis to clinical stratification: a multicentre study

BACKGROUND: To determine the diagnostic accuracy of major salivary gland ultrasonography (SGUS) in primary Sjögren’s syndrome (pSS) using the novel Outcome Measures in Rheumatology Clinical Trials (OMERACT) scoring system in a large-scale multicentre study. METHODS: SGUS was conducted for 246 pSS patients, 140 control subjects with conditions other than SS and 27 healthy control subjects. The echostructure features from the parotid and submandibular glands on both sides were graded using the novel OMERACT scoring system. Receiver operating characteristic curves were used to describe the diagnostic accuracy of the scoring system for pSS. The associations between the SGUS and disease characteristics were analysed to evaluate the clinical value of SGUS for pSS. RESULTS: The US scores in the pSS group were significantly higher than those in the non-pSS group (p < 0.001). The level of diagnostic accuracy was comparable with the scores of all four glands (AUC=0.908) when only the parotid and submandibular glands on either side were scored (AUC=0.910, 0.904, respectively). The optimal cut-off value for the left (right) parotid gland and the left (right) submandibular gland was 4, with maximal sensitivity (75.6% and 77.2%, respectively) and specificity (91.6% and 92.2%, respectively). The pSS patients with positive SGUS results presented a longer disease duration, parotid enlargement, dental loss and higher levels of serological markers, such as anti-SSA, anti-SSB, positive RF, IgG and γ-globulin%. CONCLUSIONS: SGUS with the OMERACT scoring system yields high sensitivity and specificity, demonstrating high diagnostic feasibility for pSS. The SGUS may have implications for deciding disease severity and treatment efficacy.