The presence of myositis specific and myositis associated antibodies does not alter prognosis in IPF

<bold>Background:</bold> Myositis specific antibodies (MSA) and myositis associated antibodies (MAA) can be detected in pulmonary involvement in systemic autoimmune rheumatic diseases. The prognostic effect of these antibodies in IPF however remains unclear. <bold>Methods:</bold> This is a monocentric 7-year retrospective cohort study of IPF patients from 2016 to 2022. IPF patients with MSA/MAA antibodies were age and sex matched 1:1 to IPF patients without antibodies. The 2 groups were analysed by PFTs, all-cause mortality, and presence of malignancy. <bold>Results:</bold> 17/109 (15.6%) IPF patients (12 male, 5 female) with MSA/MAA antibodies were identified. Anti-Mi2-β was detected in 6/17 (35.3%). The mean age at diagnosis was 71.9 (std +/- 8.6) and the mean disease duration was 3.79 (std +/- 2.81) years. There were no differences between groups in disease duration, smoking history, or prior malignancy. There was no difference in baseline FVC between the MSA/MAA group and the antibody negative group; 90.68% vs. 89.86% (p = 0.911). The baseline DLCO was also the same; 60.20% vs. 58.49% (p = 0.810). There was no difference in the decline in FVC predicted per year between the MSA/MAA group and the antibody negative group; -2.09% vs. -2.24% (p = 0.965). There was also no difference in the decline in DLCO per year either; -5.65% vs. -6.24% (p = 0.866). There was no difference in all-cause mortality with 5 deaths in the MSA/MAA group and 7 in the antibody negative group (p = 0.720). <bold>Conclusion:</bold> MSA/MAA antibodies do not alter disease trajectory in terms of lung function or all-cause mortality in IPF. Larger longitudinal studies are needed to determine if MSA/MAA antibodies in IPF are prognostically important or merely epiphenomena.