Improving accuracy of myasthenia gravis autoantibody testing by reflex algorithm.

Area of Science:

• Neurology
• Immunology
• Clinical Diagnostics

Background:

• Myasthenia gravis (MG) diagnosis relies on autoantibody testing, but accuracy can be improved.
• Current testing protocols may lead to false positives or negatives, impacting patient management.
• The role of additional autoantibodies in MG and associated cancers requires clarification.

Purpose of the Study:

• To enhance the accuracy and efficiency of myasthenia gravis (MG) autoantibody testing.
• To evaluate the diagnostic utility of specific autoantibody panels in conjunction with clinical and electrodiagnostic findings.
• To determine the value of reflex autoantibody testing for cancer screening in MG patients.

Main Methods:

• Retrospective review of 433 MG serologic tests over 4 years (2012-2015).
• Testing included acetylcholine receptor-binding (AChR-Bi), modulating (AChR-Mo), and striational (STR) autoantibodies, with reflex testing for muscle-specific kinase (MuSK) and cancer-associated antibodies.
• Correlation of autoantibody results with clinical-electrodiagnostic confirmation and cancer evaluations, including CT imaging.

Main Results:

• Of 433 samples, 133 met MG criteria. AChR-Bi testing achieved 90% sensitivity and 90% specificity.
• Reflexing AChR-Bi-positive cases to AChR-Mo improved specificity to 95% with a 45% reduction in false positives, maintaining 90% sensitivity.
• STR and other reflexed autoantibodies did not correlate with thymoma or other cancers; CT chest imaging remained the primary tool for cancer detection in MG.

Conclusions:

• Reflex testing of AChR-Bi-positive cases to AChR-Mo significantly improves the specificity of MG serologic diagnostics.
• STR and other reflexed autoantibodies do not add diagnostic value for cancer screening beyond standard CT imaging in MG.
• Higher AChR-Bi and AChR-Mo values correlate with increased diagnostic certainty in myasthenia gravis.