Salivary biomarkers as diagnostic and symptom severity indicators in primary Sjögren’s disease: a cross-sectional study
Arsalan Tariq, Abdul SaadObjective
To assess salivary biomarkers for diagnosing Sjögren’s disease and their relationship with symptom severity.
Methods
In this cross-sectional study, 72 patients with primary Sjögren’s disease and 76 controls (40 healthy and 36 with sicca symptoms) were recruited from tertiary care clinics and established cohorts in Lahore, Pakistan. Unstimulated whole saliva was collected under standardised conditions, and levels of beta-2 microglobulin (β2M), interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α) were measured using ELISA, multiplex immunoassays and other analytical platforms. European Alliance of Associations for Rheumatology (EULAR) Sjögren’s disease Patient Reported Index (ESSPRI) scores, Visual Analogue Scales (VASs) for dryness, fatigue and pain, as well as objective glandular measures (unstimulated salivary flow and Schirmer’s test) were recorded. Non-normal variables were analysed using the Mann-Whitney U test; correlations were assessed via Spearman’s rank coefficient. Receiver operating characteristic (ROC) curve and multivariable logistic regression analyses were performed to evaluate diagnostic performance.
Results
Patients with primary Sjögren’s disease had higher ESSPRI scores than controls (6.3 vs 2.0, p=0.005), indicating greater symptom burden. Salivary β2M, IL-6 and TNF-α were significantly elevated (p<0.01), positively correlated with ESSPRI and VAS scores and negatively with salivary flow and Schirmer’s test. ROC analyses showed strong diagnostic performance (area under the curve (AUC) 0.82–0.91), improving for the β2M+IL-6 composite (AUC 0.94) and further with anti-Sjögren's-syndrome-related antigen A(SSA) (AUC 0.97), including in anti-SSA-negative patients (AUC 0.90), supporting their use as non-invasive diagnostic and disease-monitoring tools.
Conclusion
Salivary biomarkers are effective, non-invasive indicators for diagnosing primary Sjögren’s disease and assessing symptom severity including in anti-SSA-antibody-negative.