Ab1533 Anti-Ro52 Positivity Is Associated With Poorer Lung Function at Diagnosis in Connective Tissue Disease and Idiopathic Inflammatory Myopathy Associated Interstitial Lung Disease

Background: Anti-Ro52 antibodies are detectable in multiple connective tissue diseases, particularly Sjogren's syndrome, systemic lupus erythematosus, systemic sclerosis, as well as in idiopathic inflammatory myopathies (IIM). Recent cohort studies in these patients suggest an association with anti-Ro52 positivity and more progressive interstitial lung disease (ILD) with increased morbidity and mortality. Objectives: We sought to investigate the significance of anti-Ro52 positivity in an Irish population of CTD-ILD and IIM-ILD patients. Methods: This is a monocentric 7-year retrospective combined cohort study of CTD-ILD and IIM-ILD patients treated in a specialist ILD centre. We screened 781 extended myositis panel results from 2016 to 2022 to identify a cohort of 41 CTD-ILD and IIM-ILD patients. Results: The screening process identified 41 CTD-ILD and IIM-ILD patients, (19 male, 22 female) with a mean age of 66.7 (std±13.2) and a mean disease duration of 4.4 years (std±2.6). 14 patients demonstrated anti-Ro52 antibody positivity compared with 27 who did not. The anti-Ro52+ cohort had a significantly lower baseline diffusing capacity for carbon monoxide (DLCO) at diagnosis at 41.70% predicted compared with 55.41% predicted for the anti-Ro52- cohort (p = 0.009). Baseline forced vital capacity (FVC) was numerically lower in the anti-Ro52+ cohort at 75.78% predicted versus 92.83% predicted but this did not reach statistical significance (p = 0.083). After standard of care treatment with immunosuppressive and anti-fibrotic therapies, the anti-Ro52+ cohort had comparatively poorer FVCs on their most recent pulmonary function tests (PFTs) at 72.16% predicted versus 97.06% predicted (p = 0.028). Despite relatively poorer lung function 11/14 anti-Ro52+ patients are alive today compared with 23/27 anti-Ro52- patients (p = 0.593). There was no demonstrable association between anti-Ro52 status and smoking, malignancy or ILD pattern on computed tomography (CT). Interestingly, the subgroup of patients under 65 presented with lower baseline FVC at diagnosis when compared with those over 65; 75.45% predicted vs. 95.6% predicted (p = 0.026). One hypothesis is that the younger patient is at greater risk of fulminant disease onset compared with more insidious disease progression in elderly patients. Conclusion: Anti-Ro52 antibodies are associated with a lower DLCO at diagnosis of CTD-ILD and IIM-ILD in an Irish cohort of patients. Patients under 65 also presented with a more markedly reduced FVC than those over 65, perhaps reflecting the fulminant nature of disease onset in this less elderly demographic. REFERENCES: NIL. Acknowledgements: Department of Rheumatology, Department of Respiratory Medicine, Pulmonary Function Testing Laboratory, Immunology Laboratory. Disclosure of Interests: None declared.