Ultrasonographic Evaluation of Salivary Gland Stiffness in Primary Sjögren's Disease and Idiopathic Xerostomia

ABSTRACT Background Ultrasonography is widely used to evaluate salivary gland involvement in primary Sjögren's disease (SjD). However, distinguishing SjD‐related dry mouth from idiopathic xerostomia (IX) remains challenging. This study evaluates whether elastography, an advanced ultrasonographic technique measuring gland stiffness, can improve differentiation. Methods In this retrospective study, 192 patients diagnosed with SjD ( n = 83) or IX ( n = 109) were assessed for xerostomia severity and underwent conventional, Doppler ultrasonography, and shear wave elastography (SWE) of salivary glands. Additional SjD‐related indicators, including serological and pathological markers, were analyzed. Univariate and multivariate logistic regression identified key differentiators, and generalized additive model (GAM) examined nonlinear associations. Results SjD patients showed significantly higher parotid gland stiffness (23.9 ± 10.9 kPa) compared to IX patients (15.1 ± 6.7 kPa, p < 0.0001). Additionally, submandibular gland homogeneity and parotid stiffness were independent predictors of SjD. Multivariate analysis revealed parotid stiffness as the strongest factor associated with SjD (OR = 1.152 per kPa increase, 95% CI: 1.080–1.241). GAM analysis revealed a nonlinear exposure‐response pattern, with the modeled proportion of SjD reaching approximately 50% at a parotid stiffness of 17.7 kPa. Conclusion Parotid gland stiffness shows promise as a clinical tool for distinguishing SjD from IX.