LAUSR

Background The 2017 EULAR/ACR classification criteria provide a validated scoring system for the classification of both adult and juvenile idiopathic inflammatory myopathies (IIM) with reasonable sensitivity and specificity. Objectives To assess the performance of the 2017 EULAR/ACR criteria1 in retrospective cohort of IIM and compare with Bohan and Peter criteria.2,3 Methods We conducted a retrospective study of all patients clinically diagnosed to have IIM in a tertiary care centre in the last ten years. Performance of both the criteria in the cohort was assessed and compared with clinical diagnosis. Results One hundred and seven patients were included in the study. Nine patients had juvenile onset. Clinical features are summarised in table 1. 80.4% of the patients were classified as probable/definite myositis using the Bohan and Peter criteria. 81.3% of the patients were classified as having probable/definite inflammatory myositis using the new criteria (score ≥5.5 without biopsy or ≥6.7 with biopsy). However the agreement between the two classification criteria was weak in our cohort (kappa-0.43). Complete details of muscle biopsy were available in 44 patients. In this subgroup 95.5% were classified by and Bohan and Peter and 84.1% by EULAR/ACR criteria. Both criterias performed poorly in patients without biopsy data and in polymyositis subset (table 2).Abstract FRI0436 – Table 1 Clinical features of patients with idiopathic inflammatory myositis Age (at diagnosis) 38.73 years Proximal Muscle weakness 104 (97.2%) Sex (Female:male) 3.12:1 Dysphagia 33 (30.8%) Raynauds 22 (20.6%) ILD 10 (9.3%) Arthralgia/arthritis 71 (66.4%) Anti Jo1 positivity (n=91) 3 (2.8%) ANA positivity 59 (55.1%) Elevated muscle enzymes 94 (87.9%) Clinical DiagnosisDermatomyositisAmyopathic DMPolymyositisMyositis Overlap SyndromeJuvenile DermatomyositisJuvenile onset myositis overlapCancer associated myositis 52 (48.9%)2 (1.9%)20 (18.7%)22 (20.6%)8 (7.5%)1 (0.9%)2 (1.9%) Cutaneous involvement (s/o DM)HeliotropeGottron’s papulesGottron’s SignOther rashes 65 (60.7%)35 (32.7%)21 (19.6%)8 (7.5%)18 (16.8%)Abstract FRI0436 – Table 2 Classification using Bohan and Peter and 2017 EULAR/ACR criteria Bohan and Peter EULAR/ACR Total IIM (n=107) 86 (80.4)% 87 (81.3)% With Biopsies (n=44) 42 (95.5%) 37 (84.1%) Without Biopsies (n=63) 44 (69.8%) 50 (79.4%) DM (n=67) 62 (92.5%) 61 (91.0%) PM (n=40) 24 (60%) 26 (65%) Conclusions The new EULAR/ACR criteria did not perform better than Bohan and Peter criteria in our cohort. The new criteria are more time consuming and seem to be of limited utility in daily clinical practice. References [1] Lundberg IE, et al. European League Against Rheumatism/American College of Rheumatology classification criteria for adult and juvenile idiopathic inflammatory myopathies and their major subgroups. Ann. Rheum. Dis. 2017;76:1955–1964. [2] Bohan A, Peter JB. Polymyositis and Dermatomyositis. N. Engl. J. Med. 1975;292:344–347. [3] Bohan A, Peter JB. Polymyositis and Dermatomyositis. N. Engl. J. Med. 1975;292:403–407. Disclosure of Interest None declared