Evaluating the diagnostic utility of new line immunoassays for myositis antibodies in clinical practice: a retrospective study

Montagnese, Federica; Babacic, Haris; Eichhorn, Peter und Schoser, Benedikt (2019): Evaluating the diagnostic utility of new line immunoassays for myositis antibodies in clinical practice: a retrospective study. In: Journal of Neurology, Bd. 266, Nr. 6: S. 1358-1366

Abstract

BackgroundMyositis-associated antibodies (MAA) and myositis-specific antibodies (MSA) are detected in patients with idiopathic inflammatory myopathies (IIM);their role as diagnostic biomarkers is however still debated. The aim of our study was to assess the utility of MAA/MSA assessed by new line immunoassays in detecting myositis among neuromuscular patients.MethodsWe retrospectively analysed sera samples obtained from patients tested for myositis antibodies with the Euroline: Autoimmune Inflammatory Myopathies 16Ag and myositis profile 3 kits (Mi-2, TIF1, MDA5, NXP2, SAE1, Jo-1, SRP, PL-7/12, EJ, OJ, Ro-52, Ku, PM-Scl75/100). First symptom, CK, EMG, muscle biopsy and diagnosis were also analysed. Using logistic regression analysis, two diagnostic models were built to evaluate the diagnostic power of MAA/MSA in distinguishing myositis patients from controls and other myopathies.Results1229 patients were identified. 141 patients had a bioptic confirmed IIM;other diagnoses included: myopathy (n=357), other neuromuscular diseases (n=144) and no neuromuscular diseases (n=587). The specificity was 95% for MSA and 89% for MAA, the sensitivity 20% and 22%, respectively. MAA showed no use in differentiating myositis patients from controls, whereas MSA had limited effect (OR=5.165), compared to other variables as EMG (OR=47.755) or CK>2000U/L (OR=45.307). MSA were, however, the most useful parameter differentiating IIM from non-IIM patients (OR=7.259), better than CK>2000U/L (OR=4.033) and MAA (OR=2.737).ConclusionsLine immunoassays for myositis antibodies show high specificity but low sensitivity. Their usefulness as diagnostic biomarkers widely depends on the clinical settings. Our study suggests that MSA/MAA should be used for confirmatory and differential diagnosis rather than for screening purposes in inflammatory myopathies.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Medizin
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• ISSN: 0340-5354
• Sprache: Englisch