Objectives: We aimed to assess the diagnostic accuracy of salivary gland ultrasonography (SGUS) as a single test for the detection of primary Sjögren's syndrome (pSS) and examine the prognostic factors for severe structural damage of the salivary glands based on SGUS score.
Methods: Patients with pSS (n=94) and idiopathic sicca syndrome (n=44) were evaluated using the SGUS 0-48 scoring system, which comprises five parameters: parenchymal echogenicity, homogeneity, hypoechoic areas, hyperechogenic reflections, and clearness of posterior borders. The salivary gland volume and intraglandular power Doppler signal (PDS) were also assessed. A multivariate linear regression analysis was performed to determine the factors associated with SGUS score.
Results: Patients with pSS showed a significantly higher SGUS score than controls [median (IQR): 24.5 (13.0) vs 6 (3.75), p<0.001]. An SGUS cut-off of ≥14 had a sensitivity of 80.9% and a specificity of 95.5% for the diagnosis of pSS. There were no significant differences in the measured volumes and PDS between pSS patients and controls. The SGUS score correlated with unstimulated salivary flow rate (USFR), serum rheumatoid factor and IgG. Double seropositivity with anti-Ro/SS-A and anti-La/SS-B (β=6.060, p=0.001) and USFR (β=-1.913, p<0.001) were independently associated with the SGUS score.
Conclusions: The SGUS scoring system is a valuable diagnostic method for pSS. Double seropositivity of anti-Ro/SS-A and La/SS-B along with USFR were independent predictive factors for structural damage of the salivary glands.