The diagnosis of primary Sjögren's syndrome (pSS) is complex, and the saliva test is a potential method to improve the existing diagnostic criteria.
To estimate the diagnostic accuracy of salivary anti-SSA/B antibodies in primary Sjögren's syndrome (pSS), and to analyze their correlations with clinical and laboratory profiles.
This study enrolled 100 pSS patients and 140 non-pSS controls, including 40 rheumatoid arthritis (RA) patients, 40 systemic lupus erythematosus (SLE) patients, and 60 healthy controls. Unstimulated whole saliva and stimulated parotid saliva samples were collected from the subjects. Salivary anti-SSA/B antibodies were measured using an enzyme-linked immunosorbent assay (ELISA). Clinical and laboratory data were retrieved from the medical records.
In the pSS group, the sensitivity of anti-SSA and anti-SSB antibodies in whole saliva was 49% and 29%, respectively, and the specificity was 87.5% and 95%. The sensitivity of anti-SSA and anti-SSB antibodies in parotid saliva was 32% and 8%, respectively, and the specificity was 95.52% and 97.86%, respectively. In the pSS group, the diagnostic accuracy of anti-SSA/B antibodies in whole saliva was significantly higher than in parotid saliva (p<0.05), but was significantly lower than in serum (p<0.05). The salivary flow rate in the pSS group positive for whole salivary anti-SSA was significantly lower than in the negative group (p<0.05). The prevalence of rheumatoid factor and antinuclear factor were significantly higher in salivary SSB-positive pSS patients than in SSB-negative patients (p<0.05).
Compared to parotid saliva, whole saliva is a more suitable diagnostic fluid. Using salivary anti-SSA/B antibodies as a single test item is insufficient given the relatively low sensitivity. Further studies should investigate the possibility of combining tests for different salivary autoantibodies as a method for diagnosing pSS.