Objectives: The Fatigue Symptoms and Impacts Questionnaire-Relapsing Multiple Sclerosis (FSIQ-RMS) is a new content-valid, concise, and reliable 20-item patient-reported outcome measure to evaluate the symptoms and impacts of fatigue in patients with relapsing forms of multiple sclerosis. Analyses were performed to derive meaningful change thresholds (MCTs) on patient-reported outcomes as measured by FSIQ-RMS and generate receiver operating characteristic (ROC) curves to determine fatigue severity cut points at baseline and change in severity at post-baseline and supplement the anchor-based MCT results.
Methods: Analyses were based on data from the OPTIMUM trial (NCT02425644). An anchor-based approach using uncollapsed changes on the Patient Global Impression of Severity at week 108 were used to determine the MCT for only the FSIQ-RMS Symptoms domain; distribution-based MCT estimations were conducted using baseline FSIQ-RMS Impacts scores. ROC curves with calculation of area under the curve were used to identify the best cut point.
Results: Based on the evidence provided by the anchor-based analyses using the Patient Global Impression of Severity as an anchor for the FSIQ-RMS Symptoms domain, meaningful score changes for improvement and deterioration were -6.3 and 6.3, respectively. Meaningful score changes for the FSIQ-RMS Physical, Cognitive/Emotional, and Coping Impacts domains using distribution-based methods were 10.8, 8.4, and 9.8, respectively. These results are supported by the ROC analyses.
Conclusions: Thresholds to support interpretation of the FSIQ-RMS, such as MCTs, can be used to determine and categorize patients who have experienced a meaningful change in their MS-related fatigue (eg, responder analyses) in future clinical research studies.
Keywords: fatigue; meaningful change threshold; patient-reported outcome; relapsing multiple sclerosis; symptoms.
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