How Common Are False-Positive Antibodies in Myasthenia Gravis?

Clinical Takeaway

: In a real-world retrospective analysis, the risk for false-positive acetylcholine receptor antibodies was non-negligible and more common with low titers.

Context

In patients with symptoms compatible with generalized autoimmune myasthenia gravis, clinicians consider positive antibodies against the acetylcholine receptor (AChR) to be confirmatory for diagnosis. Although a cell-based assay is more accurate, the widely available radioimmunoprecipitation assay (RIPA) remains the gold standard, with a reported specificity of 99%. Now, investigators report the diagnostic accuracy of AChR-IgG RIPA in a cohort of 4795 patients tested at a single institution.

Key results were as follows:

9.3% of patients had a positive (≥0.5 nmol/L) AChR-IgG; of those with clinical information, 13.8% were false positives as determined by a median of 8 years of clinical follow-up.
Overall specificity was 99%; positive pred…

Reviewing Author

Leana Doherty, MD

Disclosures

Editorial BoardsNeurohospitalist Society; InterACTN (Annals of Clinical and Translational Neurology)

Leana Doherty, MD

Disclosures

Editorial BoardsNeurohospitalist Society; InterACTN (Annals of Clinical and Translational Neurology)

How Common Are False-Positive Antibodies in Myasthenia Gravis?

Topics

Clinical Takeaway

Context

Reviewing Author