Sicca severity in primary Sjögren’s disease reflects symptom amplification rather than systemic inflammatory activity

Aim: To clarify whether sicca symptom severity reflects systemic inflammatory activity or symptom amplification in primary Sjögren’s disease (pSD), and to examine its relationship with functional impairment and mood disturbance in a predominantly treated cohort.Material and Methods: In this cross-sectional, single-center study, adult patients fulfilling the 2016 ACR/EULAR classification criteria for pSD were evaluated. Systemic disease activity was assessed using the EULAR Sjögren’s Syndrome Disease Activity Index. Oral and ocular dryness severity were measured using visual analog scales. Health-related quality of life was assessed with the EQ-5D-5L index and Short Form 36 physical and mental component scores, and depressive symptoms with the Beck Depression Inventory. Logistic regression models examined associations with systemic disease activity. Receiver operating characteristic analyses assessed the performance of dryness severity for identifying systemic activity and fibromyalgia. Symptom heterogeneity was explored using unsupervised cluster analysis.Results: Among 107 patients, 86.9 percent had low systemic disease activity. Sicca severity showed no association with systemic disease activity and did not predict moderate to high disease activity. Pulmonary involvement, fibromyalgia, and erythrocyte sedimentation rate were independently associated with higher systemic disease activity. Although dryness severity showed poor discrimination for inflammatory activity, it was strongly associated with fibromyalgia, depressive symptoms, and impaired quality of life. Cluster analysis identified a symptom amplification phenotype characterized by marked functional and psychological impairment despite moderate dryness severity.Conclusion: In pSD, sicca symptom severity primarily reflects functional and psychological burden rather than systemic inflammation, supporting phenotype-oriented, patient-centered assessment strategies.