Defining brain volume cutoffs to identify clinically relevant atrophy in RRMS

Area of Science:

• Neurology
• Neuroimaging
• Biostatistics

Background:

• Relapsing-remitting multiple sclerosis (RRMS) is characterized by unpredictable disability worsening.
• Normalized brain volume (NBV) is a potential biomarker for disease progression in RRMS.
• Standardized methods are needed to categorize NBV for clinical application.

Purpose of the Study:

• To establish objective criteria for classifying normalized brain volume (NBV) as low, medium, or high in RRMS patients.
• To determine if these NBV categories correlate with future disability worsening.

Main Methods:

• Calculated expected NBV (eNBV) using a regression model with baseline RRMS patient characteristics (age, disease duration, sex, EDSS, T2-lesion volume).
• Classified 2342 RRMS patients into low, medium, or high NBV groups based on observed vs. eNBV.
• Assessed the association between NBV categories and 2- and 4-year disability worsening.

Main Results:

• Low NBV was significantly associated with a higher risk of 2-year disability worsening (HR=1.75, p=0.001) compared to high NBV.
• The predictive value of NBV categories for disability worsening was maintained over 4 years.
• Treatment effects appeared more pronounced in lower NBV groups, though not statistically significant.

Conclusions:

• RRMS patients can be stratified into distinct disability risk groups using normalized brain volume (NBV) and expected NBV (eNBV) calculations.
• NBV categorization based on baseline characteristics provides a clinically relevant tool for predicting disability progression in RRMS.