Usefulness of Unstimulated and Stimulated Whole Saliva, Accuracy of Minor Labial Salivary Gland Biopsy in the Diagnosis of Primary Sjögren's Disease: A Croatian Single-Center, Cross-Sectional Study

Abstract

The aim of this cross-sectional study was to determine the accuracy of minor labial salivary gland (MLSG) biopsy in the diagnosis of primary Sjögren' s disease (pSD); to study the correlation between the focus score (FS) and anti-SSA/Ro, anti-SSB/La, anti-SSA and -SSB antibodies, unstimulated whole saliva (UWS) and stimulated whole saliva (SWS); to determine the role of UWS and SWS in the clinical evaluation of pSD patients and patients with sicca symptoms.
 Methods. A total of 37 subjects were enrolled in the study and divided into two groups: the test group consisted of 15 patients diagnosed with pSD; the control group consisted of 22 patients who had sicca symptoms but did not meet the 2016 American College of Rheumatology (ACR) and European League Against Rheumatism (EULAR) diagnostic criteria. Clinical and laboratory tests, including saliva collection, MLSG biopsy, autoantibody titers, were performed in all patients.
 Results. The median of the FS was 1.00 [IQR=1.00-1.50] in the test group, whereas in the control group, it was 0.00 [IQR=0.00-0.00] (p< 0.001). The sensitivity, specificity, and accuracy of MLSG biopsy were 86.7%, 100.0%, and 94.6%, respectively. The results showed a correlation between the FS and antinuclear antibodies (ANA) (p=0.002). In addition, Pearson’s correlation showed a weak negative correlation between UWS (r=-0.058, p=0.73) and SWS (r=-0.022, p=0.90) and the FS. In the test group, 73.3% of patients had abnormal UWS values, while 86.7% had abnormal SWS values; among them, values of 0.00 ml/min for UWS and SWS were found in 60.0% and 26.7% of patients, respectively.
 Conclusions. Although MLSG biopsy has great diagnostic value and accuracy in diagnosing pSD, it is not always definitive. Our study found a statistically significant association between the FS and ANA, and the greater utility of SWS in diagnosing pSS.