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Selected Publication:
Tiefenthaler, V.
Clinical Relevance of Myositis-Specific Antibodies
Humanmedizin; [ Diplomarbeit ] Medical University of Graz; 2019. pp. 76
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- Authors Med Uni Graz:
- Advisor:
- Stradner Martin Helmut
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- Abstract:
- Background: The detection of myositis-specific antibodies is known as an important diagnostic method of idiopathic inflammatory myopathies (IIM)(1). By conducting this study, the clinical relevance of myositis-specific and myositis-associated antibodies in the diagnostic pathway of IIMs was investigated. Therefore, one of the primary aims was to determine the positive predictive values for each studied autoantibody. Methods: The study investigated retrospectively medical records of all patients tested positive for MSA and/or MAA between October 2014 to October 2017. The patients’ medical records got analyzed thoroughly and the data was checked for predefined clinical features and laboratory parameters. The parameters necessary for the use of the new EULAR/ACR classification criteria for idiopathic inflammatory myopathies were filtered out of the medical records in order to prove the applicability of those criteria. Furthermore, correlations between positive antibody test results and the presence of an IIM subtype as well as other autoimmune diseases, malignancies or interstitial lung disease have been investigated. Finally, the positive predictive values of each tested autoantibody for suffering from an IIM subtype, for having a positive history of autoimmunity or malignancy and the PPV for having ILD were calculated. Results: The PPVs of the analyzed autoantibodies within our patient cohort for having myositis are rather low except for the PPV of anti-Jo1 (42%) and anti-Mi-2α (73%). The PPVs for having a malignant disease determined in this study are relatively low. The highest PPVs for having another autoimmune disease than myositis were obtained for anti-TIF1γ (47%), anti-PMScl-100 (52%), anti-PMScl-75 (40%), anti-PL-7 (46%) and anti-Mi-2β (43%). The prevalence of ILD in our patient cohort is not higher than 21% and hence only half of the prevalence reported in literature(2). The highest relative frequencies of ILD were found in patients positive for anti-PL-7 (25%), followed by anti-Jo-1 (21%), anti-PL-12 (15%) and anti-SRP (12%). Furthermore, the data was checked for significant correlations ending up with one significant correlation between anti-MDA5 and anti-SAE within the normal range. Finally, the EULAR/ACR classification criteria confirmed in 88% (213 patients out of 242) the actual situation of patients concerning the presence or absence of an IIM subtype. Conclusion: Since one of the primary aims was to evaluate the clinical relevance of MSA and MAA by calculating the positive predictive values for having an IIM subtype, this thesis can serve as a basis for clinicians for interpreting a positive autoantibody test result.