0513: Real-world Clinical and Diagnostic Features of Patients with Isolated Anti-SSB Antibodies Compared to Those with Combination Anti-SSA and Anti-SSB Antibodies

Background/Purpose: While Sjögren’s disease is commonly associated with anti-SSA (anti-Ro) and/or anti-SSB (anti-La) antibodies, these autoantibodies are not disease-specific and may be present in various autoimmune conditions. Emerging evidence suggests that isolated anti-SSB positivity is not strongly associated with Sjögren’s or other connective tissue diseases, whereas dual positivity for anti-SSA and anti-SSB may indicate a more severe disease phenotype [1-4]. This study aimed to compare the clinical and serologic profiles of patients with isolated anti-SSB antibodies to those with concurrent anti-SSA and anti-SSB positivity in a real-world clinical setting.

Methods: A retrospective analysis of electronic medical records from January 1, 2018, to December 31, 2022 was conducted. Adults (≥18 years) with positive serologic testing for anti-SSA and anti-SSB antibodies were included. Patients with isolated anti-SSA, negative repeat serology within six months, or insufficient clinical data were excluded. Demographic data, clinical manifestations, autoantibody profiles, and diagnostic outcomes were compared between groups. Statistical analysis included Student’s t-test and chi-squared tests for group comparisons, and univariate and multivariate logistic regression to estimate odds ratios (OR), with a significance threshold of p < 0.05.

Results: A total of 315 patients were included: 109 with isolated anti-SSB and 206 with both anti-SSA/SSB positivity. The groups were similar in age and sex distribution (83% vs. 85% female). Compared to the dual-positive anti-SSA/anti-SSB, patients with isolated anti-SSB antibody were significantly less likely to exhibit anemia, leukopenia, proteinuria, or positive ANA. Other autoantibodies (anti-Smith, anti-RNP, RF, anti-CCP) were also less frequent in the isolated anti-SSB group. Additionally, this group had lower rates of xerophthalmia and diagnoses of Sjögren’s disease, systemic lupus erythematosus, and rheumatoid arthritis, and were more often left without a rheumatologic diagnosis.

Conclusion: Isolated anti-SSB positivity is associated with a significantly lower likelihood of Sjögren’s disease, SLE, and RA. These findings suggest that isolated anti-SSB may lack diagnostic utility in connective tissue diseases and could represent a benign serologic finding in many patients.