Psychometrics and normative data for the Multiple Sclerosis Functional Composite: replacing the PASAT with the Symbol...

Area of Science:

• Neurology
• Neuroscience
• Clinical Assessment

Background:

• The Multiple Sclerosis Functional Composite (MSFC) is a key measure of neurological disability in multiple sclerosis (MS).
• Cognitive assessment within the MSFC traditionally uses the Paced Auditory Serial Addition Test (PASAT), with the Symbol Digit Modalities Test (SDMT) emerging as a potential alternative.

Purpose of the Study:

• To compare the validity and reliability of MSFC scores derived from PASAT versus SDMT.
• To evaluate the predictive power of both MSFC versions for MS diagnosis, disease course, and work disability.

Main Methods:

• Calculated MSFC scores using both PASAT and SDMT with reference populations (NMSS Task Force, MS patients, controls).
• Assessed test-retest reliability and correlations with other clinical measures (disability, depression, fatigue) in a longitudinal cohort.
• Employed logistic regression to determine predictive validity for diagnosis, course, and work disability.

Main Results:

• Both PASAT- and SDMT-based MSFC demonstrated similar test-retest reliability and correlations with other clinical indicators.
• The SDMT-based MSFC exhibited slightly superior predictive validity for MS diagnosis, disease course, and work disability.
• Variance accounted for by both MSFC versions was comparable, suggesting similar overall performance measurement.

Conclusions:

• Both PASAT and SDMT versions of the MSFC are valid measures for assessing neurological disability in MS.
• The SDMT offers a potentially advantageous alternative to PASAT due to its slightly better predictive validity and simpler administration.
• Clinicians and researchers may consider adopting the SDMT for future MSFC calculations to enhance predictive power and ease of use.