Salivary gland ultrasound integrated with 2016 ACR/EULAR classification criteria improves the diagnosis of primary Sjögren's syndrome

OBJECTIVES: To evaluate the utility of salivary gland ultrasound (SGUS) in the diagnosis of primary Sjögren's syndrome (pSS) singly or integrated with 2016 ACR/EULAR classification criteria. METHODS: Patients with suspected pSS were enrolled in the study. SGUS semi-quantitative scoring was used to assess salivary gland. Clinical characteristics were recorded, including autoantibodies, ophthalmic tests, salivary glands scintigraphy (SGS) and labial biopsy. The diagnostic accuracy of SGUS score and complementary value of SGUS to 2016 ACR/EULAR criteria were analysed. RESULTS: 282 patients were included for analysis. 161 were diagnosed as pSS and 121 as non-SS. SGUS score≥5 showed 64.7% sensitivity and 81.4% specificity for the diagnosis of pSS. Positive anti-SSA, abnormal SGS and SGUS score were significantly higher in pSS than non-SS group (80.1% vs. 14.0%, p<0.01; 91.3% vs. 57.0%, p<0.01; 8.4±6.6 vs. 2.6±3.2, p<0.01 respectively). A weighted score [(anti-SSA×16.5) + (SGS×14.5) + (SGUS×4.5)] was constructed. The score ≥17.5 could improve the sensitivity, and almost keep the specificity comparing to 2016 ACR/EULAR criteria (89.9% vs. 85.6% and 79.5% vs. 82.2%). When replacing labial biopsy by SGUS in 2016 ACR/EULAR criteria, both sensitivity and specificity were a bit decreased (85.0% vs. 85.6% and 79.8% vs. 82.2%). When adding SGUS to 2016 ACR/EULAR criteria, it showed better performance by improving the sensitivity (90.8% vs. 85.6%), while not losing the specificity (83.7% vs. 82.2%). CONCLUSIONS: Adding SGUS score to the 2016 ACR/EULAR criteria can improve the diagnosis utility of pSS. SGUS may be a feasible and prospective tool in the diagnosis of pSS.