| Purpose: In this study,the clinical and imaging data of patients with idiopathic inflammatory myopathy(IIM)were collected,and the relationship between myositis specific autoantibodies(MSA)and myositis associated autoantibodies(MAA)and diagnosis,disease activity and muscle magnetic resonance imaging(MRI)of IIM patients was discussed.To further explore the significance of myositis autoantibodies in clinical diagnosis and management of IIM.Method: The clinical data of 176 IIM patients in the No.1 hospital of Jilin University from May 2016 to September 2020 were analyzed retrospectively.Based on 2017 European League Against Rheumtism/ American College of Rheumatology,(EULAR/ACR)IIM diagnosis and classification criteria,Myositis Disease Activity Assessment Tool(MDAAT)and myositis autoantibodies detection results,the disease course,age,clinical manifestations,immunology and muscle MRI imaging results were analyzed.Results:(1)Among the 176 IIM patients,53 were male and 123 were female,the ratio of male to female was 4.3: 10.1,the age ranged from 21 to 85 years,the average age was 48.4(± 13.5)years,and the course of disease was 13.4(± 8.2)months.According to 2017 EULAR/ACR IIM diagnosis and classification criteria,83patients(47.1%)were PM,79 patients(44.8%)were DM,14 patients(7.9%)were ADM,and no IBM patients.148 patients(84.1%)were received muscle biopsy,including 74 PM patients(89.1%),63 DM patients(79.7%)with PM and 11 ADM patients(78.6%).The biopsy results among the three groups showed that PM patients had more pathological phenomenon of endomysial infiltration of mononuclear cells surrounding,while DM patients showed more perimysial and/or perivascular infiltration of mononuclear cells,and the difference was statistically significant(P<0.05).Analysis of clinical data showed that myasthenia and myalgia were more common in DM and PM subgroups than in ADM subgroups,and the difference was statistically significant(P<0.001).Compared with PM subgroup,the rash in DM and ADM subgroup(such as red rash including V sign and shawl sign,Heliotrope rash,Gottron sign and Gottron rash)was more common,and the difference was statistically significant(P<0.001),which were consistent with the diagnostic criteria.Myositis-related malignant tumors were found in 17 patients(9.7%)during follow-up,but there was no significant difference in distribution among the three subgroups(P=0.299)(2)In the study cohort,146 patients(82.9%)detected at least one MSA or MAA in serum.The anti-Jo-1was the most common MSA,and the anti-Ro-52 was the most common MAA.According to 2017 EULAR/ACR IIM diagnosis and classification criteria,there was no difference in the distribution of MAA including anti-Ro-52,anti-PM-SCL75,anti-PM-SCL100 and anti-Ku among three subgroups of PM,DM and ADM(P=0.202,P=0.130,P=0.135,P= 0.569).The anti-Mi-2α,anti-Mi-2β,anti-TIF1γ,anti-MDA5 and anti-SRP were distributed differently in three subgroups of PM,DM and ADM.The Logistical regression analysis showed that anti-Mi-2α,anti-Mi-2βand anti-SAE1 were correlated with DM,while anti-SRP antibody was correlated with PM,anti-TIF1γ antibody were correlated with both DM and ADM,and anti-MDA5 antibody was correlated with ADM(P<0.05).(3)According to the positive status of MSA and MAA,the study cohort was divided into four groups: MSA(+)MAA(+)、MSA(+)MAA(-)、MSA(-)MAA(+)、MSA(-)MAA(-).According to the diagnostic score of 2017 EULAR/ACR IIM diagnostic and classification criteria,23 patients(13.1%)were possible IIM,48patients(27.2%)were probable IIM and 105 patients(59.6%)were definite IIM.After grouping according to MSA and MAA positive conditions,there were significant differences in the distribution of diagnostic possibility among the groups(P<0.001).After post hoc analysis,there was no significant difference in the distribution of MAA in the three subgroups of possible IIM,probable IIM and definite IIM(P=0.298,P =0.586).In contrast,MSA positive patients were more distributed in the definite IIM subgroup,and the difference was statistically significant(P<0.001,P<0.001)which meant MSA positivity was related with higher diagnostic probability of IIM.(4)According to the positive status of MSA and MAA,the study cohort was divided into four groups: MSA(+)MAA(+)、MSA(+)MAA(-)、MSA(-)MAA(+)、MSA(-)MAA(-).According to MDAAT,the disease activity of each patient at the time of diagnosis was evaluated,and the disease activity was divided into muscle disease activity and extramuscular disease activity.There was no significant correlation between myositis autoantibodies and muscle disease activity(P=0.549).In contrast there was a distribution difference between myositis autoantibodies and extramuscular disease activity(P < 0.001,RR = 4.277,95% CI 3.293– 5.260).By post hoc test,it was found that the extramuscular disease activity in MSA positive patients was significantly higher than that in MSA negative patients(P=0.02,P=0.003).However,there was no significant correlation between MAA positive condition and extramuscular disease activity(P=0.832,P=0.365).(5)50 patients in the study cohort have received the MRI of thigh muscles,among which the MRI manifestations of muscle inflammatory edema,myofascitis,subcutaneous tissue edema,muscle fatification and atrophy accounted for 72.4%,20.1%,8.9% and 18.4% respectively.There was no obvious difference in the distribution of DM and PM in the above 4 subgroups.(6)According to the positive status of MSA and MAA,the study cohort was divided into four groups:MSA(+)MAA(+)、MSA(+)MAA(-)、MSA(-)MAA(+)、MSA(-)MAA(-).The distribution of muscle inflammatory edema,myofascitis,muscle fatification and muscle atrophy in each group was significantly different(P=0.005,P=0.031,P=0.04).Post hoc analysis showed that MSA positive patients were more prone to have muscle inflammatory edema,myofascitis,muscle fatification and muscle atrophy(P=0.004,P=0.041,P=0.003,P<0.001,P<0.001,P<0.001,respectively).Conclusion:(1)MSA aids the diagnosis of IIM.Under the diagnostic score of 2017EULAR/ACR IIM diagnosis and classification criteria,MSA positivitity was correlated with higher diagnostic score,higher and more certain diagnostic possibility.(2)Based on MDAAT,MSA was associated with higher activity of extramuscular system diseases,and MSA positive patients have higher activity of extramuscular system diseases than MSA negative patients.(3)MSA positive condition showed relationship with inflammatory edema,myofascitis,and muscle fatification and muscle atrophy of thigh muscles MRI. |
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