AB0445 FIRST CLINICAL ANALYSIS OF MYOSITIS PATIENTS REGISTERED AT REUMA.PT/MYOSITIS PROTOCOL: DATA FROM A SINGLE-CENTER
Authors: A. T. Melo, E. Dourado, P. Martins, N. Khmelinskii, J. E. Fonseca, I. Cordeiro, R. Campanilho-Marques
Journal: Annals of the Rheumatic Diseases (2021)

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. Table 1. Clinical characteristics and immunological profile of the patients. Diagnosis (n) Clinical features Myositis antibodies (n) Skin disease, median [IQR]/ (n ) MMT-8, median [IQR] Lung disease (n ) Others (n ) Malignancy (n ) Definite DM (28) DAS Skin 2 [0-2] Calcinosis (3) Mechanic hands (2) 80 [75-80] NSIP (2); COP (1) Arthritis (6) Breast cancer (1) anti-Ro52 (6); anti-Mi2b (5); anti-PmScl100 (4); anti-MI2a (3); anti-NXP2 (3); anti-SAE (2); anti-MDA5 (2); anti-Ku (2); anti-Tif1g (1) Antisynthetase syndrome (21) DAS Skin 0 [0-0] Calcinosis (1) Mechanic hands (4) 80 [80-80] NSIP (11); UIP (3); LIP (1) Arthritis (15); RP (10) – anti-Jo1 (14); anti-Ro52 (12); anti-Mi2b (1); anti-PL7 (3); anti-PL12 (1) Probable DM (19) DAS Skin 0 [0-0] 80 [78-80] COP (1) Arthritis (5); RP (6) – anti-Mi2a (4); anti-Mi2b (2); anti-Tif1g (2); anti-Ku (2); anti-PmScl75 (2) CADM (16) DAS Skin 1 [0-2] Calcinosis (1) Mechanic hands (1) 80 [77-80] NSIP (1); COP (1) Arthritis (5); RP (4) – anti-Mi2b (5); anti-Ro52 (2); anti-Mi2a (1); anti-MDA5 (1); anti-EJ (1); anti-SAE (1); anti-SRP (1); anti-Ku (1); anti-Tif1g (1) MCTD (12) DAS Skin 0 [0-1] 80 [79-80] NSIP (1) Arthritis (8); RP (10) – anti-U1 RNP (12); anti-Ro52 (7) PM (7) DAS Skin 0 [0-0] Calcinosis (1) 80 [72-80] NSIP (1) Arthritis (1) Ovarian cancer (1); non-Hodgkin lymphoma (1) anti-Ro52 (2); anti-SRP (1) UCTD (5) DAS Skin 0 [0-2] Calcinosis (1) Mechanic hands (1) 80 [79-80] NSIP (2) Arthritis (1); RP (5) – anti-ThTo (2); anti-SRP (1); anti-PL12 (1) Overlap syndromes (12) DAS Skin 0 [0-2] Mechanic hands (2) 80 [77-80] NSIP (3); UIP (1) Arthritis (4); RP (8) – anti-PmScl75 (4); anti-PmScl100 (1); anti-Ro52 (1); anti-Ro60 (1); anti-RNAPIII (1); anti-NOR90 (1); anti-MDA5 (1); anti-Ku (1) Necrotizing myopathy (1) DAS Skin 0 80 – – – – DM – dermatomyositis; CADM – clinically amyopathic dermatomyositis; MCTD – mixed connective tissue disease; PM – polymyositis; UCTD – undifferentiated connective tissue disease; ILD – interstitial lung disease; NSIP – nonspecific interstitial pneumonia; LIP – lymphocytic interstitial pneumonitis; UIP – usual interstitial pneumonia; COP – cryptogenic organizing pneumonia; RP – Raynaud phenomenon Disclosure of Interests: None declared.