AB0624 PREDICTIVE PARAMETERS FOR DEVELOPMENT OF INTERSTITIAL LUNG DISEASE IN IDIOPATHIC INFLAMMATORY MYOSITIS
Authors: T. Vojinovic, M. Fredi, P. Ceruti, D. Modina, F. Franceschini, I. Cavazzana
Journal: Annals of the Rheumatic Diseases (2020)

Background: Idiopathic Inflammatory Myositis (IIM) is a group of heterogeneous connective tissue diseases, primarily characterized by chronic muscle inflammation as well as myositis-specific or myositis-associated autoantibodies and a spectrum of different extra-muscular features. The most frequent organ involment in IIM is Interstitial Lung Disease (ILD), occurring in 5-80% of different IIMs cases and considered the hallmark of morbidity and mortality in patients with IIMs. Objectives: To retrospectively assess the predictive factors for development of ILD in IIM patients Methods: We retrospectively analyzed the prevalence of ILD in a single-center cohort of 165 IIM patients. Patient data was collected from clinical charts. ILD was diagnosed by chest X-ray scan and chest CT scan. All chest CT and chest X-ray scans available and performed at our hospital were consequently re-evaluated by our expert pneumologist for uniform evaluation. Results: Myositis-related ILD (M-ILD) was found in 52 IIM patients (31.5%): 46.15% was affected by anti-synthetase syndrome (ARS), 21.15% by polymyositis (PM), 19.23% by dermatomyositis (DM) and 13.46% by overlap myositis. The pulmonary involvement was characterized by Non-specific interstitial pneumonia (NSIP) (30.6%), Unusual Interstitial Pneumonia (UIP) (38.77%), Bronchiolitis Obliterans with Organizing Pneumonia (BOOP) (20.4%), overlap NSIP/BOOP (4.1%) and Undetermined/Unspecific pattern (6.12%). Eighty four percent of M-ILD consisted of non-smokers and 69.23% presented with dyspnea at onset. ILD was diagnosed in 90.38% of patients within the first year of IIM diagnosis (early onset ILD) and was associated with dyspnea and/or cough in 70.2% and 17% respectively. On the other hand, late onset ILD presented mostly with dyspnea and/or cough in 60% of cases and was significantly associated with anti-Ku antobodies. At onset ILD was significantly associated with: ARS (p&lt;0.0001; OR:12.98), anti-Jo-1 (p&lt;0.0001; OR:6.1), anti-Ro (p=0.038; OR:2.2), mechanic’s hands (p&lt;0.0001; OR:10.41), arthritis (p=0.01; OR:2.58), polyarthritis (p=0.001; OR:4.578), dyspnea (p&lt;0.0001; OR:9.66), and high levels of CPK (p=0.0001) and GOT (p=0.0146). By contrast, the following features: DM (p=0.012; OR:0.36), facial rash (p=0.003; OR:0.31), anti-NXP-2 (p=0.019; OR&lt;0.0001), anti-PL-12 (p=0,03; OR&lt;0.0001) and myositis (p&lt;0.0001; OR:0.173) present at onset were less frequently associated with M-ILD. At multivariate analysis M-ILD was predicted by anti-Ro (p=0.0448), polyarthritis (p=0.0093) and dyspnea (p=0.0001) at onset. On the other hand, patients presenting myositis (p=0.0383) and facial rash (p=0.0398) at onset were less likely to developed M-ILD. Conclusion: ILD occurs in about one third of patients with IIM, mostly affected by ARS. The presence of anti-Ro antibodies as well as polyarthritis and dyspnea at onset predict the development of ILD. Disclosure of Interests: None declared