Abstract Rationale Myositis-specific antibodies (MSA) are frequently present in Idiopathic Inflammatory Myopathies (IIM). Myositis-Associated Interstitial Lung Disease (M-ILD) is the most common extra-skeletal manifestation of IIM, often preceding skin or muscle involvement. Some patients with interstitial lung disease (ILD) and MSA do not meet diagnostic criteria for IIM, and therefore, can be categorized as idiopathic ILD with MSA (I-ILD-w/MSA). This study aims to further define patients with ILD and MSA by describing the demographics, treatment patterns, disease progression, and survival outcomes at Henry Ford Health (HFH). Methods This is a retrospective cohort study of ILD patients with MSA evaluated by a physician in the HFH ILD program. Demographics, serology, high-resolution computed tomographies (HRCT), and biopsy results were collected from initial workup. Treatment regimens were categorized as corticosteroids, immunomodulators, and anti-fibrotics. Disease course was assessed using modified medical research council dyspnea scales (mMRC), pulmonary function tests (PFT), and HRCT at follow up visits. Characteristics of M-ILD were compared to I-ILD-w/MSA. Kaplan-Meier (KM) survival curve created with death or transplant as end points. Results 126 patients met inclusion criteria, of whom, 62% were female and the mean age at presentation was 59.8±14 years. Following Rheumatology, Dermatology, and Neurology evaluation, 53 patients had a confirmed diagnosis of IIM M-ILD and 73 patients were categorized as I-ILD-w/MSA. Patients with M-ILD, when compared to I-ILD-w/MSA, were younger at presentation (53.6±12.9 vs 63.7±13.8 years, p 0.05) and more frequently had +Jo-1 antibody (58.5% vs 10.5%, p 0.05). I-ILD-w/MSA more frequently had +NXP (20.5% vs 5.7%, p 0.05). Similar proportions (24.5%, 28.8%) of each group underwent lung biopsy, where NSIP was more prevalent in M-ILD (45.3% vs 20.5%, p 0.05). The groups had similar baseline mMRC, PFT, and CT findings. At 6 month follow up, M-ILD had less dyspnea (mMRC 1.46±1.07 vs 2.10±1.2, p 0.05), improved FVC% (+3.9±9.4 vs -0.6±7.8, p 0.05), and better DLCO% (53.7%±17.6 vs 43±20.2, p 0.05). M-ILD received significantly more corticosteroids (75.5% vs 53.4%, p 0.05) and immunomodulators (69.8% vs 37%, p 0.05). KM analysis revealed a higher median survival (months) in M-ILD (73.19 vs 45.4, log-rank p 0.05). Conclusions Confirmed IIM was present in less than half of our patients with ILD and MSA, further supporting the role of MSA in ILD and its prognostic implications. Consistent with prior studies, our M-ILD cohort was younger, received more immunomodulator therapy, and had better survival compared to I-ILD-w/MSA. Future directions include assessment of treatment response within these cohorts. This abstract is funded by: None
Major et al. (Fri,) studied this question.