The international classification criteria for Sjögren's syndrome necessitate the presence of either extractable nuclear antibody or a characteristic focal inflammatory infiltrate in a minor salivary gland. Thus, patients who are extractable nuclear antibody-negative will need to have a labial salivary gland biopsy, which is an invasive procedure associated with morbidity. The aim of this study was to evaluate the viability of ultrasound imaging of the major salivary glands as a predictor of the histology to explore whether ultrasound can help in stratifying Sjögren's patients and reduce the need for biopsy.
The records of 85 patients suspected of having Sjögren's syndrome and who have had biopsy and ultrasound were analysed retrospectively. The histology and the ultrasound were reported by experts independently. The reporting was impartial as the examiners were blinded to the results of the other investigations and to the diagnosis.
Out of the 85 patients, 34 had positive ultrasound, 29 of whom also had positive histology. Fifty-one patients had negative ultrasound, of whom 49 were also negative for histological features of Sjögren's syndrome. The results show that the ultrasound had a positive predictive value of 85% and a striking negative predicative value of 96% of the histology results. The overall concordance between the ultrasound and the histology was 91% (Kappa = 0.826).
Our study shows that potentially the ultrasound has a role in stratifying patients who are extractable nuclear antibody-negative and can help to prioritize the biopsy for those who have sonographic evidence of SS.