Salivary gland ultrasonography: a highly specific tool for the early diagnosis of primary Sjögren's syndrome.

INTRODUCTION: Recently, a great interest has arisen for salivary gland ultrasonography (SGUS) as a valuable tool for the assessment of major salivary gland involvement in primary Sjögren's syndrome (pSS. The aims of this study were to test the accuracy of SGUS for the early detection of pSSand to compare the diagnostic performance of SGUS with minor salivary gland biopsy (MSGB) and unstimulated salivary flow (USFR) in this context.

METHOD: Patients with suspected pSS and symptoms duration of ≤5 years were consecutively enrolled in this study. The diagnosis of pSS was made according to the AECG criteria. SGUS was performed by two radiologists blinded to the diagnosis and a previously reported ultrasound scoring system (De Vita et al. 1992, cut-off ≥ 1) was used to grade the echostructure alterations of the salivary glands. Statistical analysis was performed using SPSS v16.

RESULTS: This study included 50 pSS patients and 57 controls with no-SS sicca symptoms. The mean(SD) age of the pSS group was lower than non-SS group (47(13) vs 53(12)yrs, p = 0.006). No further differences between the two groups were observed. Patients with pSS showed a significantly higher SGUS score in comparison with controls (mean(SD) = 2.1(1.8) vs 0.0(0.4), p = 0.000). The SGUS cut-off ≥ 1 showed a sensitivity (SE) of 66 %, a specificity (SP) of 98 %, a positive predictive value (PPV) of 97 % and a negative predictive value (NPV) of 73 % for pSS diagnosis. The SGUS score correlated also with patients' MSGB/FS and USFR.

CONCLUSIONS: This study confirmed the good performance of SGUS for the early non-invasive diagnosis of pSS. Further research in larger international cohort of patients is mandatory in order to assess the role of SGUS in the diagnostic algorithm of pSS.