AB0813 Seventeen myositis autoantibodies: serological profile of hispanic patients with idiopathic inflammatory myopathies
Authors: T.S. Gracia-Arechiga, M.A. Villarreal-Alarcon, J. Hermosillo-Villafranca, I. Pérez-Onofre, A. Guillén-Lozoya, D. Galarza-Delgado, J.P. Carrizalez Luna
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> The idiopathic inflammatory myopathies (IIM) are a heterogeneous group of subacute, chronic, or acute acquired diseases of skeletal muscle, they can be classified into the following clinical pathologic groups: dermatomyositis (DM), polymyositis (PM), and inclusion body myositis (IBM) which differ in clinical presentation, season of onset, genetics, and prognosis.(<sup>1</sup> Furthermore, the seropositivity of antibodies in these diseases can help to predict the evolution of the disease, and influence therapeutic strategies.(,<sup>2</sup> Anti-Mi-2 is a classic marker for DM and its associated with good response for steroid treatment and good prognosis. Anti-SRP is specific for PM and its associated with treatment-resistant myopathy, histologically characterised as necrotizing myopathy. Several new myositis specific antibodies (MSA), autoantibodies with strong clinical significance have been described in IIM manifestations.<sup>3</sup> The literature about this topic is limited in Hispanic population. This study represents an effort for a better understanding of this group of diseases. <h3>Objectives</h3> To determine the prevalence of myositis specific and myositis associated autoantibodies in a cohort of patients with idiopatic inflammatory myopathies, who were treated from January 2016 to January 2018 in a Rheumatology Service from a University (Hospital Jose E. Gonzalez) from UANL and a centre for arthritis at north of Mexico. <h3>Methods</h3> Cross-sectional, retrospective descriptive study cohort of 95 patients who attended the rheumatological clinic in the period from January 2016 to January 2018 who met Bohan and Peter's classification criteria. The determination of antibodies was performed by the Inmunoblot technique with Euroinmmun kit. The following serotypes were included: OJ, Ro 52, Mi2 α, MDA-5, TIF 1 gama, PM/Scl 75, Mi 2ß, SRP, PL12, PL 7, PM/Scl 100, Ku, Jo1, EJ, cN1A, NXP2, SAE 1. Statistical analysis was performed with univariate, for the categorical variables, absolute frequencies and percentages were analysed and for the numerical means and standard deviation with the SPSS V22 (Armonk, NY: IBM Corp.) <h3>Results</h3> From a cohort of 95 patients, 68.42% were women and 31.75% were men. The average age was 47±15.42. A prevalence of seropositive antibodies were observed for Mi2 α of 29 (30.52%), 14 (14.73%) in <i>Tif 1gamma</i> and 12 (12.63%) has positive<i> Mda 5.</i> <h3>Conclusions</h3> The systematic and standardised evaluation of the determination of antibodies in patients with inflammatory myopathies play an important role in the predictive evaluation. Knowledge of the prevalence and clinical scenarios in various cohorts increase the standardisation and prompt use of antibodies in the classification of inflammatory myopathies <h3>References</h3> [1] Dalakas, M.C. (2015), Inflammatory muscle disease. N Engl J Med, Volumen 372, 1734–1747. [2] Selva-O' Callaghan A, Redondo-Benito A, Trallero-Araguas E, Martinez-Gomez X, Palou E, Vilardell-Tarres M. Clinical significance of thyroid disease in patients with inflammatory myopathy. Medicine (Baltimore). 2007;86:293–8 [] 3. Lai YT, Dai YS, Yen MF, Chen LS, Chen HH, Cooper RG, Pan SL. Dermatomyositis is associated with an increased risk of cardiovascular and cerebrovascular events: A Taiwanese population-based longitudinal follow-up study. Br J Dermatol. 2013; 168: 1054–1059. <h3>Acknowledgements</h3> None <h3>Disclosure of Interest</h3> None declared