Anti-Ro52 positivity is associated with poorer lung function at diagnosis in CTD-ILD and IIM-ILD

<bold>Background:</bold> Recent cohort studies suggest an association with anti-Ro52 antibodies and more progressive ILD in CTD-ILD and IIM-ILD. This study investigates the significance of anti-Ro52 positivity in an Irish cohort of patients. <bold>Methods:</bold> This is a monocentric 7-year retrospective cohort study of CTD-ILD and IIM-ILD patients. 781 extended myositis panel results were screened from 2016 to 2022 to identify a suitable cohort. PFT data was analysed to explore the significance of anti-Ro52 positivity. <bold>Results:</bold> 41 CTD-ILD and IIM-ILD patients (19 male, 22 female) were included. The mean age was 66.7 (std +/- 13.2) and the mean disease duration was 4.4 years (std +/- 2.6). 14/41 patients were anti-Ro52+. The anti-Ro52+ cohort had a significantly lower baseline DLCO at diagnosis; 41.70% vs. 55.41% (p = 0.009). Baseline FVC predicted was numerically lower in the anti-Ro52+ cohort but did not reach statistical significance; 75.78% vs. 92.83% (p = 0.083). After standard of care treatment, the anti-Ro52+ cohort had poorer FVCs; 72.16% vs. 97.06% (p = 0.028). There was no difference in all-cause mortality with 3 deaths among the anti-Ro52+ cohort and 4 among the anti-Ro52- cohort (p = 0.673). No associations between anti-Ro52 status and smoking, malignancy or ILD pattern on CT were found. Patients under 65 presented with lower baseline FVC compared with those over 65 irrespective of anti-Ro52 status; 75.45% vs. 95.60% (p = 0.026). <bold>Conclusion:</bold> Anti-Ro52 antibodies are asssociated with a lower baseline DLCO in CTD-ILD and IIM-ILD patients. Patients under 65 also presented with a more markedly reduced FVC than more elderly patients, perhaps reflecting the fulminant nature of disease onset in this demographic.