Detection of Clinically Important Change in Multiple Sclerosis-Related Fatigue and Relationship to Cognitive Performance (P04.109)

Abstract

Objective: Evaluate 1) the responsiveness of the Modified Fatigue Impact Scale (MFIS) for multiple sclerosis (MS)-related fatigue and 2) relationships between subjective fatigue assessment and measures of cognitive function. Background MS-related fatigue, including cognitive fatigue, is common. The MFIS is routinely used to measure MS-related fatigue but its responsiveness and ability to detect clinically important change after therapy is not known. Previous research found that cognitive performance and fatigue were not related. However, potentially more sensitive instruments such as the MFIS might detect an underlying relationship. Design/Methods: Ambulatory patients with MS-related fatigue persisting at least 6 weeks completed the MFIS, Fatigue Severity Scale (FSS), SF-36, and questionnaires. Cognitive performance measures included the Paced Auditory Serial Addition Test (PASAT) and others. All testing was administered on days 0, 7, and 21. Amantadine was initiated on day 7. Global assessment of change (GAC) comparing pre-to post-treatment status was rated as poor, fair, good, or excellent. Paired t-tests and Fisher9s exact test were used to evaluate outcomes and correlations were calculated for mean change scores. Effect size and correlations between changes in MFIS, GAC, and PASAT were calculated. Results: 22 patients were enrolled. Improvement in post-treatment scores was detected for the MFIS (p=0.004) and the PASAT (p=0.02), among others. The MFIS effect size was moderate (0.61) but there was a weak association between MFIS change and GAC (r=0.26; NS). Changes in PASAT scores correlated with changes in the SF-36 physical subscale (r=0.42; p=0.05), MFIS-Cognitive subscale (r=0.39; p=0.07), and MFIS-Social subscale (r=0.37; p=0.09). Conclusions: Fatigue, as measured by the MFIS, may be associated with cognitive performance. However, despite moderate effect size, change in MFIS is not associated with qualitative self-assessment of therapeutic response. Further work is needed to find instruments that detect clinically important change in subjective fatigue and objective cognitive performance. Disclosure: Dr. Thaera has nothing to disclose. Dr. Wingerchuk has received research support from Genentech, Inc,, Genzyme Corporation, Alexion and the Guthy-Jackson Charitable Foundation.