Predictive value of myositis antibodies: role of semiquantitative classification and positivity for more than one autoantibody
Authors' conclusion
The PPV of myositis antibodies for diagnoses of myositis or other myositis spectrum diseases vary considerably between individual autoantibodies.
Study context
- Population
- Individuals ≥18 years positive for ≥1 antibody in the EUROLINE myositis line blot or for anti-HMGCR (ELISA), 2015–2020, Finland
- Participants
- 1,068 individuals
- Outcome
- PPV of 17 myositis antibodies for a diagnosis of myositis and other myositis-spectrum conditions (ILD, CTD, malignancy)
Methodological detailsregistry-based, multicentre (15 of 20 hospital districts in Finland), Clinical diagnoses extracted from the Care Register for Health Care, January 2013 to June 2022
- Registry-based
- Multicentre (15 of 20 hospital districts in Finland)
- Clinical diagnoses extracted from the Care Register for Health Care, January 2013 to June 2022
Main finding
As reported in the abstract
PPV for myositis diagnosis (ever during data collection)
Anti-HMGCR
94%
Anti-MDA5, anti-Jo-1 and anti-TIF1-γ
49-54%
Other myositis antibodies
18-42%
Observational data: associations, not effects.
Further findings
PPV for interstitial lung disease (ILD)
- Anti-synthetase antibodies, anti-MDA5, anti-PM-Scl100, anti-SAE1 and anti-Ro52
- 25-47%
PPV for connective tissue diseases (CTD)
- Highest for anti-Ro52
- 57%
PPV for malignancy
- Highest for anti-TIF1-γ
- 38%
- Anti-PL-7
- 32%
Band intensity and PPV
- Stronger band intensity associated with higher PPVs for myositis and CTD but not for ILD or malignancies
Antibody overlap and PPV
- Positivity for ≥2 antibodies vs single antibody associated with higher PPVs for myositis, CTD and ILD
Original publication
Predictive value of myositis antibodies: role of semiquantitative classification and positivity for more than one autoantibody. RMD Open. Published 20 January 2025. doi:10.
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