SAT0484 Performance of the 2017 eular/acr classification criteria for inflammatory myositis and their major subgroups in the remicam (REGISTRY OF INFLAMMATORY MYOPATHIES IN THE MADRID COMMUNITY)

• Published in: Annals of the rheumatic diseases Vol. 77; no. Suppl 2; p. 1099
• Main Authors: Rabadán, E., Joven, B.E., Lozano, F., Nuño, L., López-Longo, F.J., Martínez-Barrios, J., Larena, C., Blazquez, M., Barbadillo, C., Llorente, I., Pérez, A., Cobo, T., Almodovar, R., Lojo, L., Calvo, R., García de Yébenes, M.J., Carreira, P.E.
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group LTD 01.06.2018
• Subjects: Agreements; Biopsy; Classification; Clinical trials; Data processing; Dermatomyositis; Inflammation; Inflammatory diseases; Muscle strength; Musculoskeletal diseases; Myositis; Polymyositis
• ISSN: 0003-4967; 1468-2060
• DOI: 10.1136/annrheumdis-2018-eular.6843

BackgroundA collaborative EULAR/ACR Project has developed new criteria for inflammatory myopathies(IM) and their subgoups1 ObjectivesTo analyse agreement between the 2017 IM classification criteria and the Bohan and Peter(BP) criteria in REMICAM cohort2 MethodsAll patients were included. New criteria were applied to obtain classification as: possible(Pos), probable(Pro) and definitive(Def) IM, and subclassification in 6 subgroups: polymyositis(PM), dermatomyositis(DM), juvenile DM(JDM), amiopathic DM(ADM), inclusion body myositis(IBM) and juvenile myositis(JM). The 7 subgroups in REMICAM were harmonised to fit the 6 subgroups of the 2017 criteria. Agreement between 2017 and BP criteria was analysed in classification/subclassification, calculating the weighted kappa value (k). Subanalysis including only patients with available data on the muscle strength items required for the 2017 criteria, and in those having also muscle biopsy data, were conducted.ResultsFrom 479 REMICAM patients, 477 (99.6%), fulfilled BP criteria (5.9%Pos, 26.8%Pro, 67.4%Def) and 431 (89.9%) 2017 criteria (2.5%Pos, 21.8%Pro, 65.7Def). Global agreement between both criteria was 89.5%. Agreement between subtypes (Pos, Pro, Def) was low (k=0.15). When 399 patients with muscle strength data, and 243 with muscle biopsy data were analysed, results were similar (k=0.17). Disagreement was mainly seen in Pos/Pro subtypes with BP criteria, since 60% classified as Def when the 2017 criteria were applied. Agreement in the different subgroups of IM (PM, DM, JDM, ADM, IBM, JM) between both criteria was very high (k=0.94).ConclusionsThe new 2017 EULAR/ACR criteria for IM classification show good agreement with BP criteria in the REMICAM cohort. New criteria classify 60% of Pos/Pro patients by BP criteria, as Def, and show very high agreement between IM subgroups. Validation studies are needed, but our results in this large cohort suggest the 2017 criteria might be useful for clinical trials and research in IM.References[1] Lundberg IE. Ann Rheum Dis2017;76:1955–64.[2] Nuño L. Rheumatol Clin2017;13:331–7.Disclosure of InterestNone declared