Ab1178 Systemic Sclerosis Specific Autoantibodies in an Unselected Cohort of Patients With Raynaud’s Phenomenon: Prevalence and Clinical Associations

Background: Raynaud's phenomenon (RP) is a vasospastic condition seen in approximately 5% of the general population, classified into primary (idiopathic) and secondary (in the presence of an underlying disorder). The latter may precede the onset of systemic autoimmune rheumatic diseases (SARDs) and particularly systemic sclerosis (SSc) by many years and therefore, it can serve as a warning sign for systemic autoimmunity, coupled with the appropriate laboratory investigations. While the prevalence and prognostic value of classical SSc autoantibodies (Anti-centromere, anti-Scl70, RNA polymerase III) in the setting of SSc are well defined, data on the prevalence and clinical significance of newer SSc autoantibodies among patients presenting with RP is limited. Objectives: The aim of this study is to determine the prevalence, distribution, and clinical associations of a wide spectrum of SSc autoantibodies in patients presenting with RP either alone or along with other clinical features. Methods: The study population included 150 consecutive patients with RP referred to "Molecular Physiology and Clinical Applications Unit, Department of Physiology, National and Kapodistrian University of Athens" for evaluation of the full spectrum of SSc-specific autoantibodies using a commercially available immunoblot kit EuroLine Systemic Sclerosis Profile (IgG). Reactivities against CENPA and B, PM/Scl 75 and 100, Scl-70, Ku, NOR90, RP11, RP155, fibrillarin, PDGFR, Th/To and Ro52 autoantigens) were tested in all study participants. Moreover, clinical, laboratory and imaging features were recorded for all patients following thorough chart review. For patients tested positive for SSc-specific autoantibodies, additional work up including, pulmonary function tests, cardiac ultrasound and chest high resolution computed tomography (HRCT) imaging were performed upon clinical indication. Statistical analysis was performed by Graphpad prism 10.0 and SPSS 26.0. Results: In this cohort, the prevalence of patients with positive SSc autoantibodies and anti-Ro52 was 38.7% (58 out of 150) and 14% (21 out of 150), respectively (Figure 1A). The frequency of ANA≥1/160 was 64.5%. The distribution of reactivities among positive SSc autoantibodies ranking from higher to lower frequencies was the following: 26.7% for anti-CENPA & CENPB, 22.1% for anti-PM/Scl75&100, 15.1% for anti-RP11/155, 10.5% for anti-Scl-70, 9.3% for anti-Th/To, 7.0% for anti-Ku, 5.8% for anti-fibrillarin and 3.5% for anti-NOR90 (Figure 1B). Patients with positive antibodies had a higher percentage of sclerodactyly than those without positive antibodies (8.6% vs 1.1%, p value=0.032), while there were no significant associations with other classical signs of SSc. Two out of twelve patients with antibodies against RP11/155 were diagnosed with breast cancer (16.7%). In SSc autoantibody positive patients, the mean±SD values for FEV1/FVC, FVC, DLCO, TLC and RVSP were 90.9±10.3, 103.5± 15.7, 79.3± 12.9, 97.1±12.2 and 27.5±4.4, respectively. Four out of 18 patients (22.2%) tested had an estimated pulmonary arterial pressure of more than 30mmHg on cardiac ultrasound. Thoracic HRCT performed in 44 patients with positive serum titers of SSc autoantibodies upon clinical indication revealed the presence of abnormal findings in 28 (63.6%) including ground glass abnormalities, fibrotic lesions, bronchiectasis, peribronchial thickening and the presence of emphysema. Conclusion: A wide spectrum of SSc autoantibodies is frequently identified in patients presenting with RP in an outpatient rheumatology setting in association with sclerodactyly. Follow up studies are warranted to clearly define their prognostic role in early diagnosis of SSc or other SARDs and prompt detection of internal organ involvement.REFERENCES: NIL. Acknowledgements: Asimina Karampela and Christos Stylianopoulos contributed equally to this work. Disclosure of Interests: Clio Mavragani SOBI, Lilly, Pfizer, UCB, Abbvie, Boehringer Ingelheim, Lilly, Abbvie, Vasiliki Koulouri: None declared, Asimina Karampela: None declared, Christos Stylianopoulos Lilly, Charalampos Skarlis: None declared, Nikolaos Marketos: None declared.