AB0446 DEMOGRAPHIC AND CLINICAL FEATURES OF IDIOPATHIC INFLAMMATORY MYOSITIS AND PREVALENCE OF MYOSITIS-RELATED ANTIBODIES

Background: Idiopathic inflammatory myopathies (IIM) are heterogeneous groups of connective tissue diseases. Diagnosis IIM is sometimes challenging, but newly defined myositis specific autoantibodies (MSAs) helpful in diagnosing and revealing the clinical signs [1]. Objectives: To describe demographic features IIMs to evaluate frequency associations myositis-specific associated antibodies (MAAs) IIM. Methods: Samples obtained from patients tested for MSA/MAA as 2017 2020 were retrospectively evaluated. Patients diagnosed with according clinician diagnosis. The prevalence myositis-related assessed univariate multivariate analysis. Results: 152 (70.4% female) during study period. 81 (38 DM, 43PM). DM at an earlier age its association malignancy was more relevant, although relationship not statistically significant. Differences characteristics between PM skin which frequent interstitial lung disease common patients. MSAs/MAAS found 65.4% 43.2% patients, frequently than without (p=0.000 0.0225, respectively). MSAs equally both groups, whereas MAAs group (although no significant difference overlap other diseases within these two diseases). most anti-TIF1-γ (23%), anti-MDA5 (16%), anti-NXP2 (13%) anti-Jo-1 (28%), (12%), anti-ku anti-PL7 (12%) respectively. Predictors ILD Anti-Jo-1 positivity (RR:10 [CI:2-41] p=0.003 RR:1.07 [CI:1.02-1.12] p=0.04 respectively) Conclusion: general frequencies similar literature, except that (14%) our Turkish cohort [2]. References: [1]Cruellas, M.G., et al., Myositis-specific myositis-associated autoantibody profiles their a large series polymyositis dermatomyositis. Clinics (Sao Paulo), 2013. 68 (7): p. 909-14. [2]Gonzalez-Bello, Y., Myositis-Specific Antibodies Myositis-Associated With Inflammatory Myopathies From PANLAR Myositis Study Group. J Clin Rheumatol, 2020. Table 1. Baseline (n=38) (n=43) P Female, n (% ) 27 (71.1) 29 (67.4) 0.457 Age onset, years 33 (15-48) 47 (38-58) 0.002 Skeletal muscle Muscle weakness, 34 (89.5) 37 (86.0) 0.451 Myalgia, 23 (60.5) 30 (69.8) 0.261 Artritis, 8 (21.1) 9 (20.9) 0.601 Skin features, Heliotrope rash, 18 (47.4) 0 (0) <0.001 Gottron papules, 25 (65.8) sign, Generalize erythema, 10 (26.3) Calcinosis, 4 (10.5) 1 (2.3) 0.143 Dysphagia, n(% 12 (27.9) 0.537 Interstitial (ILD), 20 (47.6) 0.012 Other overlap, 6 (15.8) 13 (30.2) 0.102 Malignancies, 5 (13.5) 3 (7) 0.275 Laboratory data Creatine kinase (IU/L 505 (110-3616) 801 (402-1868) 0.655 C-reactive protein (mg/dl 0.3 (0.1-0.8) 1.2 (0.5-2.8) ESR (mm/h 19 (8-27) (17-48) 0.005 (Ro-52, pm-scl 100, pm-scl75), 11 (28.9) 24 (55.8) 0.013 MSAs, 28 (73.7) (58.1) 0.108 Anti- TIF1- γ, (23.7) 2 (4.7) 0.014 Anti-Jo-1, (5.3) 0.007 Anti-PL-7, (11.6) 0.038 Disclosure Interests: None declared.