Evaluation of multiple sclerosis disability outcome measures using pooled clinical trial data

OBJECTIVE: We report analyses of a pooled database by the Multiple Sclerosis Outcome Assessments Consortium to evaluate 4 proposed components of a multidimensional test battery. METHODS: Standardized data on 12,776 participants, comprising demographics, multiple sclerosis disease characteristics, Expanded Disability Status Scale (EDSS) score, performance measures, and Short Form–36 Physical Component Summary (SF-36 PCS), were pooled from control and treatment arms of 14 clinical trials. Analyses of Timed 25-Foot Walk (T25FW), 9-Hole Peg Test (9HPT), Low Contrast Letter Acuity (LCLA), and Symbol Digit Modalities Test (SDMT) included measurement properties; construct, convergent, and known group validity; and longitudinal performance of the measures individually and when combined into a multidimensional test battery relative to the EDSS and SF-36 to determine sensitivity and clinical meaningfulness. RESULTS: The performance measures had excellent test–retest reliability and showed expected differences between subgroups based on disease duration and EDSS level. Progression rates in detecting time to 3-month confirmed worsening were lower for T25FW and 9HPT compared to EDSS, while progression rates for LCLA and SDMT were similar to EDSS. When the 4 measures were analyzed as a multidimensional measure rather than as individual measures, progression on any one performance measure was more sensitive than the EDSS. Worsening on the performance measures analyzed individually or as a multidimensional test battery was associated with clinically meaningful SF-36 PCS score worsening, supporting clinical meaningfulness of designated performance test score worsening. CONCLUSION: These results support the use of the 4 proposed performance measures, individually or combined into a multidimensional test battery as study outcome measures.