To evaluate the clinical value of serological indicators combined with conventional ultrasound and contrast-enhanced ultrasound scoring in the diagnosis of primary Sjögren's syndrome syndrome (pSS).

A total of 161 suspected pSS patients who visited the First Affiliated Hospital of Wenzhou Medical University from June 2017 to December 2018 were prospectively selected as the research subjects. Their baseline data were recorded, and relevant laboratory tests, diagnostic tests, and labial gland pathological examinations were performed. The enrolled patients were divided into either a pSS group (83 cases) or a non-pSS group (78 cases). The parotid gland and submaxillary gland of all patients were scored according to a 4-point scoring system after salivary gland ultrasonographic examination, and contrast-enhanced ultrasound examination was performed to obtain contrast parameters. Logistic regression analysis was performed to screen parameters and construct a contrast-enhanced ultrasound contrast scoring equation. Four pSS diagnostic models were constructed by combining serological indicators with total ultrasound score, contrast-enhanced ultrasound score, and labial gland pathological grade. The diagnostic efficacy of the four models for pSS was evaluated by receiver operating characteristic (ROC) curve analysis. The area under the ROC curve (AUROC) of the models was compared by DeLong test, and their sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio were calculated.

Compared with the non-pSS group, the median ultrasound total score was higher (8 vs 4, P＜0.001), the median gradient of submandibular gland imaging parameters (Grad) (1.36 vs 1.94, P＜0.001), the median area under the time intensity curve (Area) (876.49 vs 954.27, P=0.003), the median peak gland intensity (PI) (-51.20 dB vs -49.20 dB, P=0.001), and the median difference in gland intensity (ID) was smaller (15.90 dB vs 17.80 dB, P=0.003), and the median time to peak (TTP) of submandibular gland contrast agent was greater in the pSS group (10.01 s vs 9.10 s, P=0.046). A scoring equation for contrast-enhanced ultrasound was constructed as follows: y=7.760-1.534 × submandibular gland Grad. ROC curve analysis of four pSS diagnostic models showed that the AUROC of serological indicators combined with total ultrasound score for the diagnosis of pSS was 0.860; the AUROC of serological indicators combined with contrast-enhanced ultrasound, score, serological indicators combined with pathological grade, and serological indicators combined with contrast-enhanced ultrasound score and total ultrasound score was 0.854, 0.941, and 0.892, respectively. The diagnostic efficacy of serological indicators combined with contrast-enhanced ultrasound score and ultrasound total score was significantly superior to that of serological indicators combined with contrast-enhanced ultrasound score or ultrasound total score (P=0.024 and 0.015, respectively). However, there was no significant difference in diagnostic efficacy between serological indicators combined with pathological grade and serological indicators combined with contrast-enhanced ultrasound score and ultrasound score total score (P=0.066).

The combination of serological indicators, ultrasound score, and contrast-enhanced ultrasound score can improve the diagnostic efficacy for pSS, and its diagnostic efficacy is comparable to that of serological indicators combined with labial gland pathology. Such diagnostic model can avoid excessive invasive examination to a certain extent.