Ultrasonography in the diagnosis of suspected primary Sjögren's syndrome and concordance with salivary gland biopsy: a Spanish single-center study.

OBJECTIVE: The study aims to evaluate the utility of major salivary gland ultrasonography for diagnosis of primary Sjögren's syndrome (pSS) and to assess its concordance with minor salivary gland biopsy (MSGB). METHODS: A cross-sectional study of 72 patients with suspected pSS was performed. Demographic, clinical, and serological data were collected. MSGB was performed, as was ultrasonography. The ultrasound technician was blind to clinical, serological, and histological data. The validity of ultrasonography compared with MSGB, the American-European Consensus Group (AECG), and American College of Rheumatology (ACR)/European Alliance of Associations for Rheumatology (EULAR) criteria was assessed by calculating the percentage of agreement, sensitivity, specificity, positive and negative predictive values, and area under the curve (AUC). RESULTS: Based on MSGB as the gold standard, the percentage of agreement between both tests was 78% (AUC 0.75). Based on the ACR/EULAR criteria, the percentage of agreement was 83% (AUC 0.78) for ultrasonography and 81% (AUC 0.83) for biopsy. Sensitivity and specificity were 90% and 67%, respectively, for ultrasonography and 76% and 90% for biopsy. The results were similar with the AECG criteria. The intra- and inter-observer variability was good (κ > 0.7). Significant differences were observed for positive anti-Ro52 values and hypergammaglobulinemia in pathological ultrasound scans. CONCLUSION: Diagnostic ultrasonography is as useful as MSGB in pSS. Therefore, it could be included in the classification criteria. In this cohort, it proved more sensitive than MSGB and could be used as an initial test for patients suspected of having pSS. MSGB could be used in cases where clinical and serological results are inconclusive. Key Points • Major salivary gland ultrasonography adds diagnostic value similar to that of MSGB, thus potentially enabling this invasive procedure to be avoided. • Ultrasonography could be included in the classification criteria for primary Sjögren's syndrome. • Given that ultrasonography is more sensitive and less specific than MSGB, it could be used as an initial diagnostic test in patients with suspected Sjögren's syndrome. • Biopsy should be performed in those cases where ultrasonography, clinical, and serological data are inconclusive.