Associations of diagnostic findings with disease activity in primary Sjogren's syndrome: a cluster analysis

Objective: The diagnosis of primary Sjogren's syndrome still relies upon a constellation of clinical, laboratory, imaging, and pathological findings. We aimed to evaluate the relation of the disease activity with the results of diagnostic tests for primary Sjogren's syndrome. Methods: A principal component with cluster analysis was performed to classify 69 patients with primary Sjogren's syndrome based on the results of diagnostic evaluations. Results: Anti-SSA autoantibody was the most represented feature on the principal components. The anti-SSA and ultrasound score were positively correlated (p=0.001). We identified two distinct clusters of low or high disease activity (p<0.001). Except for disease duration and serum beta2-microglobulin, the clusters were significantly different in salivary flow (p=0.004), ultrasound findings (p<0.001), IgG (p=0.001), and salivary beta2-microglobulin (p=0.048). Also, positive findings were significantly different between the clusters in rheumatoid factor, antinuclear antibody, anti-SSA, and anti-SSB (all p <= 0.013). Conclusion: Patients with higher syndrome activity were best recognized with serological and ultrasound assessments. However, patients with lower syndrome activity had a longer disease duration, higher stimulated salivary flow rate, and a positive biopsy of minor salivary glands (56%). (C) 2023 Elsevier Espana, S.L.U. and Sociedad Espanola de Medicina Interna (SEMI). All rights reserved.