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 explor e its utility in different subgroups of MS and for comparison with the Expa nded Disability Status Scale (EDSS). Method: Three clinical dimensions were examined: arm/hand function, leg function/ambulation, and cognition. Predi ctions of relative scores on the MSFC and its components in three major MS phenotypes (relapsing-remitting, primary progressive, and secondary progres sive) and three strata of disability were developed and tested. Also, corre lations with EDSS were calculated and the effect of an external reference p opulation was assessed. Results: Mean MSFC score was positive in the relaps ing-remitting (0.4) and mildly disabled (0.4) groups and negative in the se condary progressive (-0.3), primary progressive (-0.4), and moderately (-0. 07) and severely disabled (-1.0) groups. The correlation between EDSS and M SFC was strong (-0.68). EDSS correlated strongly with ambulation in seconda ry and primary progressive patients and severely disabled patients, moderat ely with arm/hand function for all analyzed groups, and not at all with cog nition. Comparison with an external reference population showed changes in MSFC- and Z-scores, but did not result in altered differences between the s ubgroups. Conclusion: Our prospective study in subgroups of MS confirmed an d extended the construct validity of the MSFC. The MSFC also showed good co ncurrent validity with the EDSS, and includes information about cognition.