| Background Idiopathic inflammatory myopathies（IIMs）is a group of heterogeneous diseases characterized by chronic inflammation of skeletal muscle,resulting in muscle weakness.It often involves other organs such as the skin,joints,lungs,gastrointestinal tract and heart,leading to high level of morbidity and mortality.And Myositis specific autoantibodies（Myositis-specific autoantibodies,MSAs）is a powerful diagnostic tool.The IIMs and its various subgroup classification are vital for understanding of the underlying disease process,different MSAs and PM/DM closely related to clinical phenotype.Different subtypes in clinical course have different responses to treatment.More research evidences show that Anti-MDA5 antibodies might become a potential prognostic marker of DM.Objective 1.To understand the clinical features and 1-year survival rate of patients with positive anti-MDA5 antibody in Polymyositis（PM）and Dermatomyositis（DM）.2.To clarify the effect of positive anti-MDA5 antibody on the prognosis of PM/DM patients.Methods A retrospective analysis and comparison are acted in 64 cases without clear myopathy diagnosis of PM/DM/dermatomyositis（Clinically amyopathic dermatomyositis,CADM）patients（18 anti MDA5 antibody positive cases,AntiMDA5 antibody negative 46 cases）of clinical manifestation,laboratory examination,treatment and prognostic risk factors between January 2000 and April 2020 in An Hui Medical University Hospital.Chi-square test,Mann-Whitney,Fisher-test,t-test,kaplanmeier method and log-rank test were used for statistical analysis.Results（1）There was no significant difference in age between the positive and negative anti-MDA5 antibody groups（52.722±10.991 vs.51.370±12.643,P=0.692）,and no significant difference in sex ratio between two groups（61.1% vs.34.8%,P= 0.055）.However,positive anti-MDA5 antibody was more common in DM/CADM,and the difference was statistically significant（94.4% vs.5.6%,P=0.0060）.In laboratory test,ESR,Ferritin,CK level in positive group are much higher than negative group [16.000（6.500,38.000）vs.33.000（18.500,46.750）,P=0.016;266.10（129.500,510.850）vs.1133.000（685.000,2616.000）,P=0.000;537.500（69.250,1868.750）vs.91.000（51.000,286.000）,P =0.020].There was no statistically significant difference between WBC,CRP,NLR and LDH [8.025（5.689,10.033）vs.6.000（4.438,10.300）,P =0.079;4.800（1.681,22.000）vs.7.533（2.993,12.200）,P =0.784;4.063（2.890,6.427）vs.4.117（3.005,7.457）,P=0.492;327.000（222.000,464.000）vs.315.000（253.000,469.500）,P=0.948];In terms of clinical manifestations,12 patients with positive anti-MDA5 antibody showed joint pain more often（66.7%）,while 16 patients with negative antiMDA5 antibody showed joint pain（34.8%）.The difference between the two groups was statistically significant（P=0.021）.10 patients with positive anti-MDA5 antibody had rash,especially Gottron（55.6%）,and 9 patients with negative anti-MDA5 antibody had Gottron（19.6%）.The difference between the two groups was statistically significant（P=0.005）.However,9（50%）patients with positive anti-MDA5 antibody showed cough,11（61.1%）patients with dyspnea and 7（38.9%）patients with fever,20（43.5%）patients with negative anti-MDA5 antibody showed cough,21（45.7%）patients with dyspnea and 14（30.4%）patients with fever,with no statistically significant difference in all clinical manifestations.In complications,anti-MDA5 antibody positive patients,17 cases（94.4%）than anti-MDA5 antibody negative group,29 cases（63.0%）patients with combination of interstitial pneumonia,difference was statistically significant（P= 0.012）,in addition to anti-MDA5 antibody positive patients with pulmonary fibrosis 0 cases（0）,infection,7 cases（38.9%）,large dose hormone + immunosuppressant 8 cases（44.4%）,small dose of hormone + immunosuppressive treatment of 9 cases（50%）and hormone therapy only 1 case（5.6%）,In the negative anti-MDA5 antibody group,there were 6 cases（13.0%）of pulmonary fibrosis,11 cases（23.9%）of infection,16 cases（34.8%）of high-dose hormone + immunosuppressant therapy,19 cases（41.3%）of low-dose hormone +immunosuppressant therapy,and 11 cases（23.9%）of hormone therapy alone.There was no statistically significant difference between two groups（P>0.05）.（2）The death rate of 3 cases（16.7%）in 18 patients of the anti-MDA5 antibody positive group was higher than that of 1 patient（2.2%）in the anti-MDA5 antibody negative group,with no statistically significant difference（c2=2.494,P=0.114）.（3）Among the patients with positive anti-MDA5 antibody,there was no statistically significant difference in the prognosis of 2（66.7%）patients with high dose of hormone + immunosuppressive therapy,1（33.3%）patients with low dose of hormone + immunosuppressive therapy and 0（0）patients with positive anti-MDA5 antibody only in the death group（P>0.05）.（4）The overall one-year OS rate between the 64 patients with positive and negative anti-MDA5 was 94.3%.The one-year OS rate of anti-MDA5 positive patients（76.2%）was lower than that of anti-MDA5 negative patients（97.4%）,and the difference between the two groups was statistically significant（P=0.034）.（5）The survival group with infection of 14 patients（23.3%）of PM/DM patients were significantly lower than that of 4 patients（100.0%）of the death group,and the difference between two groups was statistically significant（P=0.006）.（6）There was no statistical significance difference in gender Male（41.7% vs.50.0%,P = 1.000）,age（51.483 ± 12.409 vs.55.750 ± 6.238,P= 0.500）in survival and death group of PM/DM patients;the survival group clinical manifestations [26 cases of cough（43.3%）,chest tightness and breathlessness in 29 cases（48.3%）,arthralgia in 25 cases（41.7%）,fever in 19 cases（31.7%）,clinical manifestations of death group [cough in 3 cases（75.0%）),Chest tightness and shortness of breath in 3 cases（75.0%）,arthralgia in 3 cases（75.0%）,fever in 2 cases（50.0%）,the difference was not statistically significant（P> 0.05）.Rash in the survival group [Gottron in 18 cases（30.0%）,the heliotrope rash in 12 cases（20.0%）,other 11 cases（18.3%）,no rash in 19 cases（31.7%）,death group rash [Gottron in 1 case（25.0 %）,2 cases of the heliotrope rash（50.0%）,other 0 cases（0）,no 1 case（25.0%）,there was no statistically significant difference in rash between the two groups（P> 0.05）;Survival in treatment 22 cases（36.7%）of high-dose hormone + immunosuppressive group,27 cases（45.0%）of lowdose hormone + immunosuppressive treatment,and 11 cases（18.3%）of hormone-only treatment;death group high-dose hormone + immunosuppressive agent 2 cases（50.0%）,low-dose hormone + immunosuppressive treatment in 1 case（25.0）,only hormone treatment in 1 case（25.0%）,the difference between the two groups was not statistically significant（P> 0.05）;in complications In terms of survival,43 cases of interstitial pneumonia（71.7%）,6 cases of pulmonary fibrosis（10.0%）,death group 3 cases of interstitial pneumonia（75.0%）,and 4 cases of pulmonary fibrosis（100.0%）.There was no statistically significant difference between two groups（P> 0.05）.There were no significant differences in laboratory indicators（WBC,CRP,ESR,NLR,Ferritin,CK,LDH）between two groups（P> 0.05）.Conclusion Anti MDA5 antibody can predict the development of PM/DM patients and provide evidence for their diagnosis and treatment.The prognosis of patients with positive anti MDA5 antibody is worse than that of patients with negative anti MDA5 antibody. |
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