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SAT0314 Pregnancy in Adult-Onset Idiopathic Inflammatory Myopathy. Report from A Cohort of Myositis Patients from A Single Center

Background Idiopathic inflammatory myopathies (IIM) are systemic diseases, characterized by the presence of an inflammatory muscle infiltrate. Although more frequent in women, its relationship with pregnancy has not been extensively studied. Objectives Our goal was to analyze the interaction between pregnancy and myositis in a cohort of IIM women from a single center. Methods Fifty-one patients from a historical cohort of IIM diagnosed between 1983 and 2013 were interviewed with a specific questionnaire. Comparisons between pregnancies occurring before and after the onset of the disease were performed using generalized mixed-effect models with normal and binomial distributions adjusted for confounding factors and clustering. Results One-hundred and two pregnancies from 51 patients (41 dermatomyositis [DM] and 10 polymyositis [PM]) were analyzed. Fourteen (13.7%) pregnancies from 8 patients (5 DM, 3 PM) occurred after disease onset; clinical improvement during gestation was evident in 7 pregnancies (4 patients), 5 of them (from 2 patients) experienced a relapse of IIM symptoms afterwards, while in the rest there was no influence of pregnancy on the disease. No disease flare associated with pregnancy was observed. Two (3.9%) patients (2 DM) were diagnosed within the first 6 months after delivery and none during pregnancy. No evidence was found to support pregnancy as a trigger for myopathy (p=0.10). Conclusions Pregnancy does not seem to carry a worse prognosis for the mother nor for the fetus in patients with IIM; on the contrary, near half of the patients in our series improved clinically when they became pregnant, being common a relapse of IIM symptoms afterwards. Pregnancy does not appear to be a trigger for IIM. References Vincze M, Danko K. Idiopathic inflammatory myopathies. Best Pract Res Clin Rheumatol. 2012;26:25-45. Rider LG, Miller FW. Deciphering the clinical presentations, pathogenesis, and treatment of the idiopathic inflammatory myopathies. JAMA. 2011;305:183.90. Mastaglia FL, Phillips BA. Idiopathic inflammatory myopathies: epidemiology, classification, and diagnostic criteria. Rheum Dis Clin North Am. 2002;28:723-41. Vargas-Leguás H, Selva-O'Callaghan A, Campins-Martí M, et al. Polymyositis-dermatomyositis: incidence in Spain (1997-2004). Med Clin (Barc). 2007 24;129:721-4. Silva CA, Sultan SM, Isenberg DA. Pregnancy outcome in adult-onset idiopathic inflammatory myopathy. Rheumatology (Oxford) 2003;42:1168-72. King CR, Chow S. Dermatomyositis and pregnancy. Obstet Gynecol 1985;66:589-92. Gutierrez G, Dagnino R, Mintz G. Polymyositis/dermatomyositis and pregnancy. Arthritis Rheum 1984;27:291-4. Kanoh H, Izumi T, Seishima M, Nojiri M, Ichiki Y, Kitajima Y. A case of dermatomyositis that developed after delivery: the involvement of pregnancy in the induction of dermatomyositis. Br J Dermatol 1999;141:897-900. Vancsa A, Ponyi A, Constantin T, Zeher M, Danko K. Pregnancy outcome in idiopathic inflammatory myopathy. Rheumatol Int 2007;27:435-9.12. De Man YA, Dolhain RJ, van de Geijn FE, Willemsen SP, Hazes JM. Disease activity of rheumatoid arthritis during pregnancy: results from a nationwide prospective study. Arthritis Rheum. 2008;59:1241–8. Acknowledgements We thank Dr. Pari Basharat and Dr. Arash Lahoutiharahdashti for their critical review of the project. Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.1571