Objective: To evaluate the association between the degree of involvement shown by parotid scintigraphy at diagnosis and the disease expression, outcomes, and prognosis of primary Sjögren's syndrome (SS).
Methods: All patients consecutively diagnosed with primary SS in our department between 1984 and 2008 were evaluated. The scintigraphic stages were classified into class 4 (severe involvement), class 2-3 (mild to moderate involvement), and class 1 (normal results).
Results: A total of 405 patients with primary SS underwent parotid scintigraphy at diagnosis (47 had class 1 involvement, 314 had class 2-3, and 44 had class 4). Patients with class 4 had a higher frequency of parotid enlargement (p < 0.001), systemic involvement (p = 0.007), high titers of antinuclear antibody (p = 0.016), positive rheumatoid factor (p = 0.002), anti-Ro/SSA (p = 0.001), anti-La/SSB (p = 0.001), low C4 levels (p = 0.001), and low CH50 (p = 0.001) in comparison with the other 2 groups. A higher rate of lymphoma development was observed in patients with class 4 involvement. Adjusted multivariate Cox regression analysis showed a hazard ratio (HR) of 10.51 (p = 0.002) and Kaplan-Meier analysis a log-rank of 0.0005. Mortality was 5-fold higher in patients with class 4 involvement. Adjusted multivariate Cox regression analysis showed an HR of 5.33 (p = 0.001) and Kaplan-Meier analysis a log-rank of 0.033.
Conclusion: Patients with SS presenting with severe scintigraphic involvement at diagnosis had a more pronounced autoimmune expression, a higher risk of developing systemic features and lymphoma, and a lower survival rate. Study of the degree of salivary gland dysfunction at diagnosis by parotid scintigraphy offers valuable clinical information on the prognosis and outcome of primary SS.