CLINICAL PHENOTYPE OF ANTINUCLEAR ANTIBODY NEGATIVE SYSTEMIC SCLEROSIS IN A COHORT OF SYSTEMIC SCLEROSIS ROMANIAN PATIENTS

Background Autoantibody formation is one of the hallmarks of systemic sclerosis (SSc). Previous studies suggested that SSc patients who are antinuclear antibody (ANA) negative constitute a distinct subset of SSc patients associated with a better prognosis, defined by male dominance, less vasculopathy and more frequent lower gastrointestinal involvement [1,2]. Objectives To examine clinical and serologic correlations of Romanian SSc patients without ANA/SSc-related autoantibodies (Abs). Methods This was a single-center retrospective study which enrolled 270 SSc. The presence for both circulating SSc-related autoAbs and ANA was screened. Demographic and clinical features, symptoms and parameters related to a specific organ involvement according to MEDS evaluation sheets, were evaluated. Results We identified a population of 32 (12%) patients who had neither SSc-related autoAbs nor ANA. The group comprised 27 females and 5 males, with a mean age of 59.7 (±14.3) years, most of them with diffuse subset (25/32). ANA/SSc-related autoAbs negative patients had a significantly younger disease onset (48 [8-76] vs 60.5 [20-81] years, P <.005), longer disease duration (6 [0.1-50] vs 2 [0.1-25] years, P <.001), lower mRSS (7 [2-21] vs 9 [1-23], P <.001) but higher European Scleroderma Study Group (ESSG) activity index (5.3 [0.1-50] vs 2.9 [0.1-25] P <.001), higher proportion of synovitis (42% vs 16%, P <.001) and calcinosis (42% vs 17%, P <.001). For organ involvement, although the absence of SSc-related autoAbs was positively correlated with presence of digital ulcers (P < 0.001), heart and severe pulmonary involvement (P < 0.001), we didn’t find a statistically significant difference between the two groups. Patients negative for ANA/SSc-related autoAbs more frequently received corticosteroids (58% vs 14%, P <.0001) and immunosuppressants (16% vs 0.5%, P <.0001) than those positive SSc-related Abs. No differences in mortality were found between the groups. Conclusion Our data revealed that ANA/SSc-related autoAbs negative patients are younger and have more frequently diffuse skin involvement, inflammatory arthritis, and calcinosis. Although digital ulcers, severe pulmonary and heart involvement were more common, there was no statistically difference between the two groups. Even though overall disease activity index was significantly higher in seronegative SSc patients, no difference in mortality were found between the groups. Whether the absence of detectable autoAbs persists and is to be viewed as a favorable prognostic factor are questions to be addressed by future studies. References [1]Hudson M, et al. Prevalence and clinical profiles of autoantibody-negative systemic sclerosis subjects. Clin Exp Rheumatol. 2014;32:S127-S132. [2]Salazar GA, et al. Antinuclear antibody-negative systemic sclerosis. Semin Arthritis Rheum. 2015;44(6):680-6 Acknowledgements: NIL. Disclosure of Interests None Declared.