Anti-SSA/SSB-negative primary Sjögren's syndrome showing different clinical phenotypes: a retrospective study of 934 cases

ABSTRACT

Abstract Background Currently, only a few studies have described the general characteristics of patients with primary Sjögren's syndrome (pSS) who tested negatives for anti-SSA and anti-SSB antibodies. We aimed to further investigate the clinical characteristics of these patients in a large sample. Methods Data from patients with pSS who were treated at a tertiary hospital in China between 2013 and 2022 were retrospectively analyzed. Clinical characteristics of the patients were compared between those with and without anti-SSA and anti-SSB antibody negativity. Factors associated with anti-SSA and anti-SSB negativity were identified by logistic regression analysis. Results Overall, 934 patients with pSS were included in this study, among whom 299 (32.0%) tested negative for anti-SSA and anti-SSB antibodies. Compared with patients testing positive for anti-SSA or anti-SSB antibodies, that testing negative for the two antibodies had a lower proportion of females (75.3% vs. 90.6%, p < 0.001) and thrombocytopenia (6.7% vs. 13.6%, p = 0.002), but a higher proportion of abnormal Schirmer I tests (96.0% vs. 89.1%, p = 0.001) and interstitial lung disease (ILD) (59.2% vs. 28.8%, p = 0.001). Anti-SSA and anti-SSB negativity was positively associated with male sex (odds ratio [OR] = 1.86, 95% confidence interval [CI] 1.05, 3.31), abnormal Schirmer I tests (OR = 2.85, 95% CI 1.24, 6.53), and ILD (OR = 2.54, 95% CI 1.67, 3.85). However, it was negatively related to thrombocytopenia (OR = 0.47, 95% CI 0.24, 0.95). Conclusion Approximately one third of pSS patients had anti-SSA and anti-SSB negativity. pSS patients testing negative for anti-SSA and anti-SSB showed a higher risk of abnormal Schirmer I tests and ILD, but a lower risk of thrombocytopenia.