This study aims to compare clinical and laboratory features of patients who, while satisfying the American European Consensus Group (AECG) criteria for primary Sjögren's syndrome (SS), do not present the positivity for anti-Ro/SSA and/or anti-La/SSB, with patients that meet the AECG criteria and are positive for anti-Ro/SSA and/or anti-La/SSB.
548 patients were selected based on the following criteria, and exclusion of patients negative for histopathology but positive for anti-Ro/SSA and anti-La/SSB: 1. Fulfilment of the AECG criteria, 2. Performance of minor salivary gland biopsy, 3. Search for anti-Ro/SSA and anti-La/SSB, 4. Absence of hepatitis C virus infection. Univariate and multivariate analyses were performed.
Two groups were compared: 342 patients were positive for both the histopathology and for anti-Ro/SSA and/or anti-La/SSB (H-only) and 206 patients were positive for histopathology, but negative for autoantibodies (H+SSA/SSB). The following variables were statistically found to be associated with H+SSA/SSB: younger age at diagnosis (p<0.0001), glandular swelling (p=0.01), purpura (p=0.04), leucopoenia (p=0.0001), lymphoma (p=0.002), low C3 (p=0.04), low C4 (p=0.01), hypergammaglobulinemia (p<0.0001), ANA (p<0.0001), rheumatoid factor (p<0.0001), and serum cryoglobulins (p=0.039). ANA positivity (OR 6.9), hypergammaglobulinemia (OR 5.1), positive rheumatoid factor (OR 2.3), and age at diagnosis (OR 0.97) were also selected by multivariate analyses as associated with H+SSA/SSB.
Primary SS negative for anti-Ro/SSA and anti-La/SSB antibodies appears to be characterized by a lower risk of lymphoma and by a lower level of B-cell expansion.