特发性炎症性肌病的分类： 基于临床表现和肌炎特异性抗体

目的 应用聚类方法探讨基于临床表现和肌炎特异性抗体的特发性炎症性肌病（IIM）的疾病分类。方法 回顾性分析2015~2019年期间就诊于南方医院符合纳入及排除标准的IIM患者，收集血清肌酸激酶（CK）、间质性肺炎（ILD）、合并肿瘤、肌炎特异性抗体等临床资料，通过二阶聚类法进行疾病分类，并分析不同聚类组的临床特征。结果 共71例IIM患者纳入本研究，其中多发性肌炎（PM）30例（42.3%），经典皮肌炎（DM）20例（28.2%），无肌病皮肌炎（CADM）16例（22.5%），免疫介导的坏死性肌病（IMNM）5例（7.0%）；二阶聚类将IIM分为3类；第1类患者典型临床特征为皮疹、抗MDA5抗体阳性和低蛋白血症（P<0.05），CK正常或略高，主要对应CADM[占15例（51.7%）]；第2类患者CK值及抗SRP抗体阳性率显著较高（P<0.001），对应IMNM[占4例（57.1%）]；第3类主要为PM患者，以抗合成酶抗体阳性为主要特点（P=0.022），与抗合成酶抗体综合征（ASS）密切相关[占17例（48.6%）]。结论 本研究基于临床和血清学特征（特别是肌炎特异性抗体）的聚类分析表明IIM可分为3个亚组，其中ASS是具有独特临床特征的IIM疾病亚群，研究提供了新的IIM分类思路。

Classification of idiopathic inflammatory myopathies based on clinical manifestationsand myositis-specific antibodies

Objective To investigate the classification of idiopathic inflammatory myopathies (IIM) based on clinicalmanifestations and myositis- specific antibodies using cluster analysis. Methods We retrospectively analyzed the data ofpatients with IIM admitted in Nanfang Hospital in 2015-2019. The clinical data of the patients including serum creatine kinase(CK), interstitial lung disease (ILD), cancer, and myositis-specific antibodies were collected for two-step cluster analysis toidentify the distinct clusters of patients, whose clinical characteristics were subsequently analysed. Results A total of 71patients with IIM were included in this study, including 30 (42.3% ) with polymyositis (PM), 20 (28.2% ) with classicdermatomyositis (DM), 16 (22.5% ) with amyopathic dermatomyositis (CADM), and 5 (7.0% ) with immune-mediatednecrotizing myopathy (IMNM). Two-step cluster analysis identified 3 distinctive subgroups: Cluster 1 of 15 (51.7%) patientscharacterized by rash, positive anti-MDA5 antibody and hypoproteinemia (P<0.05) with normal or slightly elevated CK level,mainly corresponding to CADM; Cluster 2 of 4 (57.1%) patients with significantly elevated CK and positive anti-SRP antibody(P<0.001) corresponding to IMNM; and Cluster 3 of 17 (48.6%) patients consisting primarily of patients with PM, characterizedby positivity for anti- aminoacyl transfer RNA synthetases antibodies (P=0.022) corresponding to antisynthetase syndrome(ASS). Conclusions Patients with IIM can be divided into 3 subgroups based on their clinical and serological characteristics(especially myositis-specific antibodies), and among them ASS may represent an independent IIM subgroup with uniqueclinical characteristics.