Salivary gland ultrasonography as a predictor of clinical activity in Sjögren’s syndrome

PURPOSE Primary Sjögren's syndrome is a multisystem autoimmune disease characterized by hypofunction of salivary and lacrimal glands and possible multi-organ system manifestations. Over the past 15 years, three sets of diagnostic criteria have been proposed, but none has included salivary gland ultrasonography. However, recent studies support its role in the diagnosis and prognostic evaluation of patients with Sjögren's syndrome. This study aimed to determine the value of salivary gland ultrasonography in the diagnosis and prognosis of Sjögren's syndrome by relating ultrasonography severity scores to clinical and laboratory data. METHODS Seventy patients who fulfilled the 2002 American-European Consensus Group diagnostic criteria for primary Sjögren's syndrome were selected from 84 patients receiving care in specialized outpatient clinics at our institution from November 2013 to May 2016. Their serology, European League Against Rheumatism Sjögren's syndrome disease activity index (ESSDAI), salivary flow rate, immunoglobulin G, and salivary and serum beta-2 microglobulin levels were measured. Salivary gland ultrasonography was performed by an experienced radiologist, using scores of 1-4 to classify salivary gland impairment. RESULTS Salivary gland ultrasonography scores of 1 or 2 were associated with an ESSDAI < 5. Ultrasonography scores of 3 or 4 were associated with an ESSDAI ≥5 (p = 0.064), a positive antinuclear antibody test (p = 0.006), positive anti-Ro/SSA antibodies (p = 0.003), positive anti-La/SSB antibodies (p = 0.077), positive rheumatoid factor (p = 0.034), and immunoglobulin G levels > 1600 mg/dL (p = 0.077). Salivary flow rate was lower in patients with scores 3 or 4 (p = 0.001). CONCLUSION This study provides further evidence that salivary gland ultrasonography can be used not only for diagnosis but also for prognostic evaluation of primary Sjögren's syndrome. These findings confirm what has been reported in the literature. However, further analyses involving larger matched samples are required to support this finding and include salivary gland ultrasonography as part of the diagnostic criteria for Sjögren's syndrome.