IgG Index Revisited: Diagnostic Utility and Prognostic Value in Multiple Sclerosis

Area of Science:

• Neurology
• Clinical Diagnostics
• Biomarkers

Background:

• Multiple sclerosis (MS) diagnosis is challenging, especially in Asian populations.
• Routinely measured immunoglobulin G (IgG) index may offer diagnostic and prognostic value.
• Oligoclonal band (OCB) status is a key diagnostic marker for MS.

Purpose of the Study:

• To evaluate the diagnostic and prognostic utility of the IgG index in Asian MS patients.
• To assess the IgG index as a surrogate for OCB testing.
• To integrate the IgG index into existing MS diagnostic criteria.

Main Methods:

• Retrospective study of clinically isolated syndrome (CIS) patients in China with known OCB and IgG index status.
• Evaluation of IgG index predictive value for OCB positivity.
• Testing diagnostic and prognostic utility of IgG index alone and within modified McDonald criteria.
• Comparison of diagnostic utility across different criteria sets.

Main Results:

• IgG index > 0.7 predicted OCB positivity in CIS patients (P < 0.001).
• Elevated IgG index was prognostic of increased clinical relapses and disability worsening.
• IgG index > 0.7 increased the likelihood of MS diagnosis in CIS patients, particularly when OCB status was unknown or positive.

Conclusions:

• The IgG index > 0.7 predicts OCB positivity at initial MS attack and indicates early disease activity.
• IgG index is a valuable, easily obtainable surrogate for OCB testing in MS diagnosis among Asian populations.
• Incorporating IgG index into diagnostic criteria may enhance MS detection and prognosis assessment.