The multiple sclerosis functional composite: a clinically meaningful measure of disability.

BACKGROUND: The Multiple Sclerosis Functional Composite (MSFC) provides a focused and sensitive evaluation of disability in patients with multiple sclerosis (MS) that may be more responsive to change than that provided by the Expanded Disability Status Scale. EXPERT CLINICAL OPINION: The MSFC is a 3-part quantitative instrument that measures arm, leg, and cognitive function with the 9-Hole Peg Test (arm/hand dexterity), the Timed 25-Foot Walk (leg function), and the Paced Auditory Serial Addition Test (3-second version, PASAT3; cognition). The MSFC has excellent test-retest reliability. Construct validity was supported by expected differences in scores between patients with primary or secondary progressive MS compared with relapsing-remitting MS. Concurrent validity was demonstrated by significant correlations with the Expanded Disability Status Scale, the Sickness Impact Profile, and the Short Form-36, particularly on the physical components of the latter 2 scales. MSFC scores also correlate with MRI changes. Limitations of the MSFC include practice effects with the PASAT and to a lesser extent the 9-Hole Peg Test, variations in the reference populations used to calculate Z-scores, and the lack of an accepted definition of a clinically meaningful change. FUTURE DIRECTIONS: Future research should be directed at adding a test that measures visual function (e.g., contrast acuity), at replacing the PASAT by a cognition test that has better measurement characteristics, and at developing methods to better understand the clinical relevance of changes in MSFC scores.