Cut-off matters in the interpretation of myositis antibodies by line immunoassay
Authors' conclusion
Establishment of local cut-offs and cross-reference ANA findings can significantly enhance the assay's performance and increase the confidence in interpreting MAs results by LIA.
Study context
- Population
- Sera from patients with positive myositis antibodies, disease controls and healthy controls118 MA-positive, 124 disease controls (DC), 60 healthy controls (HC) · disease controls 124 · healthy controls 60
- Comparison
- Newly established local cut-offs vs manufacturer's single cut-off for myositis antibodies by line immunoassay (LIA) (EUROLINE Myopathies 16 Ag)
- Outcome
- False-positive and multiple positive rates
Performance
As reported in the abstract
False-positive rate in controls, manufacturer's vs new cut-offs
36.7% to 5.0%
Multiple positive rate in controls, manufacturer's vs new cut-offs
7.2% to 1.1%
False-positive rate in MA-positive patients, manufacturer's vs new cut-offs
45.8% to 23.8%
Multiple positive rate in MA-positive patients, manufacturer's vs new cut-offs
23.7% to 15.5%
Further findings
PPV of myositis antibodies (MAs) for idiopathic inflammatory myopathies (IIMs) or ILD
- PPV increased significantly
- from 47.5% to 66.7%
Parts of this Brief are withheld: the automatic checks could not confirm them against the abstract.
Original publication
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