Test Battery for Evaluating Fatigue in Multiple Sclerosis Patients

Fatigue is a complex symptom of multifactorial origin that affects an individual's functioning on many levels. It is the most common symptom in multiple sclerosis (MS), with nearly 50% of patients reporting daily fatigue. However, a universal definition and corresponding definitive measure of fatigue are notably absent. The purpose of this study was to examine multiple measures of fatigue to establish a test battery that could be used as an outcome to succinctly and sufficiently measure fatigue in MS patients with mild to moderate disability. Data were collected on 73 MS patients across functional domains via performance-based, physiological, and self-report measures. In all, 30 variables were examined through Pearson correlation to eliminate unrelated and redundant variables. They were then reduced to a set of dimensions by principal components analyses. Ultimately, 5 components (eigenvectors) within 15 variables were identified: dynamic functional capacity, muscular strength, fine motor control, self-reported fatigue, and voluntary motor drive. This 5-component model accounted for 77% of the variance in the data. The findings are the framework for investigating change in performance and functioning, thereby providing an efficient model with which to assess the implications of fatigue in MS during the course of everyday life.