AB0445 FIRST CLINICAL ANALYSIS OF MYOSITIS PATIENTS REGISTERED AT REUMA.PT/MYOSITIS PROTOCOL: DATA FROM A SINGLE-CENTER

Background: Idiopathic inflammatory myopathies are a group of rare heterogeneous diseases that require a multidisciplinary and standardized approach. Objectives: To clinically characterize patients with inflammatory myopathies followed at an hospital’s Rheumatology Department, using the Rheumatic Diseases Portuguese Register (Reuma.pt). Methods: An observational transversal study was performed. Data on demographic variables, clinical features, antibodies and treatment were collected. Results: Of the 121 included patients, 78% were female, with a median age of 56 [44-68] years and a median disease duration of 2 [0-4] years. The most frequent diagnosis was dermatomyositis (DM; n=28, 23%) followed by antisynthetase syndrome (ASyS; n=21, 17.4%). At the time of the analysis, the median Manual Muscle Test (MMT-8) was 80 [78-80], the median modified skin Disease Activity Score was 0 [0-2] and global disease activity was 0.5 [0-0.75]. Calcinosis was found in 6% of the patients (n=7), mostly DM cases. Interstitial lung disease (ILD) was present in 29 patients (24%), of those, 52% (n=15) had antisynthetase syndrome (ASyS). Three patients presented as a paraneoplastic syndrome. Ninety-nine patients (82%) had a myositis autoantibody identified: antisynthetase autoantibodies were the most commonly identified (n=20, 16%). 62% of the patients were treated with steroids and 35% with ≥2 disease-modifying anti-rheumatic drugs. Table 1 depicts the main clinical characteristics and the immunologic profile for each diagnosis Conclusion: In our cohort the most frequent myositis subtype was DM. Almost a quarter of patients had associated ILD, which is an important cause of morbidity and mortality. ILD was more frequent in ASyS patients and was most commonly related to anti-Jo1 antibodies, which is consistent with the literature. Disclosure of Interests: None declared.