Diagnostic value of a novel salivary gland ultrasound scoring system in IgG4-related sialadenitis

Abstract

Objectives: To develop a novel ultrasound scoring system for the major salivary glands in patients with immunoglobulin G4-related sialadenitis (IgG4-RS) and assess its diagnostic value in a multicentre cohort of Chinese patients.

Methods: Twenty clinicians (rheumatologists, stomatologists and radiologists) participated. The study was conducted in four steps: (i) defining the ultrasonography (US) elements, (ii) developing a novel ultrasound scoring system for US of the salivary glands, (iii) evaluation of inter- and intra-reader reliabilities using the new ultrasound scoring system, and (iv) assessing the diagnostic value of this novel ultrasound scoring system in IgG4-RS patients in a Chinese multicentre cohort.

Results: A novel ultrasound scoring system for the salivary glands was developed, with total scores ranging from 0 to 34. The inter- and intra-reader reliabilities of the ultrasound scoring system were excellent (0.972 and 0.940, respectively). A total of 470 people were recruited in this study; 187 patients were diagnosed with IgG4-RS, and the remaining 283 people were diagnosed with non-IgG4-RS. Patients with IgG4-RS group had significantly higher US scores than the non-IgG4-RS group (mean US score = 16 vs 4, P < 0.001). The calculated area under the curve for the total US score was 0.852 (95% CI: 0.814, 0.891). The total US scores ≥9 showed a sensitivity of 75.4% and a specificity of 91.9%. Association analysis showed a positive correlation between total US scores and serum IgG4 levels and hypocomplementaemia (r = 0.221 and r = 0.349, respectively; P = 0.002 and P < 0.001, respectively) and a negative correlation between total US scores and serum C3 and C4 levels (r = -0.210 and r = -0.303, respectively; P = 0.005 and P < 0.001, respectively).

Conclusion: A novel semiquantitative ultrasound scoring system for patients with IgG4-RS was developed, with good diagnostic performance. The inter- and intra-reader reliabilities were excellent. US scores were correlated with IgG4, C3 and C4 levels and hypocomplementaemia.

Keywords: IgG4-related disease; salivary gland; scoring system; sialadenitis; ultrasonography.