AB0697B VALIDATION OF 2017 CLASSIFICATION CRITERIA FOR ADULT AND JUVENILE IDIOPATHIC INFLAMMATORY MYOPATHIES PROPOSED BY EULAR/ACR IN CHINESE PATIENTS
Authors: Xiaohui Zhang, Xinlei Yang, Lanlan Ji, Zhuoli Zhang
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Idiopathic inflammatory myopathies(IIMs) are heterogeneous disorers characterized by muscle weakness and muscle inflammation.Although the Bohan and Peter criteria proposed in 1975 are most widely used<sup>[1,2]</sup>, there are some limitations. Firstly, they did not clearly specify how to exclude other forms of myopathy disease. Secondly, each criterion is not well defined either. EULAR and aCR jointly proposed the classification criteria for adult and juvenile IIMs and their major subgroups in 2017. The data-driven criteria exhibited high sensitivity and specificity. But most of the patients (62.6%) in the data were Caucasians, the performance of the criteria in asian patients is unknown, which was one of the important limitations<sup>[6,7]</sup>. <h3>Objectives</h3> To evaluate the ability of 2017 EULAR/ACR Classification Criteria for adult and Juvenile Idiopathic inflammatory Myopathies (IIM) to classify IIM in comparison with 1975 Bohan and Peter criteria in Chinese patients. <h3>Methods</h3> Two hundred and twenty-one in-patients with suspected IIM (including 40 children) were retrospectively included in this study. The performance of 2017 EULAR/ACR criteria was evaluated by sensitivity, specificity, positive predictive value, negative predictive value and classification rate, in comparison to the 1975 criteria, with clinical diagnosis as the gold standard. <h3>Results</h3> The sensitivity, specificity, positive predictive value, negative predictive value of the 2017 EULAR/ACR criteria in IIM classification were 92.7%, 87.0%, 90.1% and 90.4% respectively, in contrast to the 1975 Bohan and Peter criteria of 84.0%, 52.2%, 61.8%, and 77.9%(Fig 1). The classification rate of 2017 criteria was also much better than that of 1975 criteria (90.2% vs. 67.4%). The performance of the new criteria in general, as well as the new criteria with muscle biopsy was better. Most IIM patients were correctly further subclassified by the classification tree. The positive rate of myogenic lesion in electromyography (EMG), muscular inflammatory edema in magnetic resonance Imaging (MRI) and specific antibodies of myositis were significantly higher in IIM group than those in control group (p&lt;0.001, all). <h3>Conclusion</h3> The 2017 EULAR/ACR criteria exhibited high sensitivity, specificity, classification rate in the Chinese IIM patients, which was superior to the 1975 criteria. The new criteria showed potentials as clinical classification criteria in the future. * referred to the overall assessment, including patients "score of ≥ 5.5 without biopsies and score of ≥ 6.7 with biopsies <h3>References</h3> [1] Bohan a, Peter JB: Polymyositis and dermatomyositis (first of two parts). N Engl J Med1975, 292:344-347. [2] Bohan a, Peter JB: Polymyositis and dermatomyositis (second of two parts). N Engl J Med1975, 292:403-407. [3] Lundberg IE, Tjarnlund a, Bottai M, Werth VP, Pilkington C, de Visser M, alfredsson L, amato aA, Barohn RJ, Liang MH, et al: 2017European League against Rheumatism/American College of Rheumatology Classification Criteria for adult and Juvenile Idiopathic inflammatory Myopathies and their Major Subgroups. Arthritis Rheumatol 2017, 69:2271-2282. [4] Lundberg IE, Tjarnlund a, Bottai M, Werth VP, Pilkington C, Visser M, alfredsson L, amato aA, Barohn RJ, Liang MH, et al: 2017European League against Rheumatism/American College of Rheumatology classification criteria for adult and juvenile idiopathic inflammatory myopathies and their major subgroups. Ann Rheum Dis2017, 76:1955-1964. <h3>Disclosure of interests</h3> None declared