Background Anti-SSa/Ro antibodies are among the common antibodies found in Systemic Sclerosis (SSc) patients (prevalence range 15–38%). Recent studies have suggested the association of anti-SSa/Ro with interstitial lung disease (ILD) as well as their prognostic role in SSc patients, however its definitive importance is yet to be determined.
Objectives To determine the prevalence of anti-SSa/Ro antibodies in a cohort of SSc patients and its association with clinical and serological features.
Methods Observational retrospective cohort study was performed including consecutive patients with clinical diagnosis of SSc (based on expert opinion) followed in our Rheumatology Department. Demographic, clinical and laboratorial data were obtained from clinical records. Lung involvement was considered if ILD was detected by an experienced radiologist in high-resolution computed tomography. Extractable Nuclear Antigen Antibodies, including ant-SSA/Ro, were measured in all the patients included, using enzyme-linked immunosorbent assay (ELISA) method. Patients with positive anti-SSa/Ro were compared with the other patients using Mann-Whitney, t-student, χ2 and Fisher tests (SPSS 23.0). Significance level was set as <0.05.
Results 108 patients were included, 96 (90%) were females with a mean age of 58.2±12.8 years and a median disease duration of 6 years [0–38]. 12 (11%) patients had diffuse SSc and 96 (89%) limited SSc. Anti-SSa/Ro antibodies were present in 13 (12%) patients and were the third most common antibodies after anti-centromere (57%) and anti-Scl70 (20%). In the anti-SSa/Ro group, 11 (84.9%) were females and the mean age was of 61.1±12 years. Comparing to non-anti-SSa/Ro patients, both groups were similar regarding demographical data, disease duration and type of skin involvement. Anti-SSa/Ro group had more frequent SSc-Overlap syndromes (SSc-OS) (54% vs 15%, p=0.003). Anti-SSa/Ro group had significantly more frequent ILD (54% vs 18%, p=0.01) with no differences regarding the pattern of lung disease. No statistically significant differences were found regarding frequencies of myopathy, pulmonary hypertension, gastrointestinal, renal and cardiac involvement. There was a greater proportion of neoplasia and joint involvement in the anti-SSa/Ro group (23% vs 6% and 54% vs 27%, respectively), not reaching statistical significance. Anti-SSa/Ro patients had significantly more frequent anti-Scl70 antibodies (46% vs 17%, p=0.02) and Rheumatoid Factor (31% vs 6%, p=0.018), without differences regarding other antibodies. No differences in mortality were found between the groups.
Conclusions Anti-SSa/Ro antibodies were among the most common antibodies in our cohort of SSc patients. Consistently with previous data, our study supports their association with SSc-OS and ILD without evidence for other clinical features. Finally, our study also demonstrates a greater proportion of anti-Scl70 antibodies in these patients.
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Disclosure of Interest None declared