MS functional composite: relation to disease phenotype and disability strata

Objective: The MS Functional Composite (MSFC), a recently developed outcome measure for clinical trials, was applied to 240 patients with MS to explore its utility in different subgroups of MS and for comparison with the Expanded Disability Status Scale (EDSS). Method: Three clinical dimensions were examined: arm/hand function, leg function/ambulation, and cognition. Predictions of relative scores on the MSFC and its components in three major MS phenotypes (relapsing-remitting, primary progressive, and secondary progressive) and three strata of disability were developed and tested. Also, correlations with EDSS were calculated and the effect of an external reference population was assessed. Results: Mean MSFC score was positive in the relapsing-remitting (0.4) and mildly disabled (0.4) groups and negative in the secondary progressive (-0.3), primary progressive (-0.4), and moderately (-0.07) and severely disabled (-1.0) groups. The correlation between EDSS and MSFC was strong (-0.68). EDSS correlated strongly with ambulation in secondary and primary progressive patients and severely disabled patients, moderately with arm/hand function for all analyzed groups, and not at all with cognition. Comparison with an external reference population showed changes in MSFC- and Z-scores, but did not result in altered differences between the subgroups. Conclusion: Our prospective study in subgroups of MS confirmed and extended the construct validity of the MSFC. The MSFC also showed good concurrent validity with the EDSS, and includes information about cognition.