The measurement of fatigue in patients with multiple sclerosis. A multidimensional comparison with patients with chronic fatigue syndrome and healthy subjects.

OBJECTIVE To provide a multidimensional characterization of fatigue in patients with multiple sclerosis (MS). DESIGN Cross-sectional design. Fifty patients with clinically definite MS were compared on the dimensions of fatigue with 51 patients with chronic fatigue syndrome (CFS) and 53 healthy subjects. RESULTS Fourty-six percent of the patients with MS reported fatigue to be present at least once a week. Patients with MS and patients with CFS had significantly higher subjective fatigue severity scores than healthy subjects. Patients with MS and patients with CFS had significantly higher scores on measures of psychological well-being than healthy subjects. Patients with MS had scores similar to those of patients with CFS, except that patients with CFS had significantly higher somatization scores. High somatization scores reflect strong focusing on bodily sensations. Both groups of patients were significantly less active than the healthy subjects. The Kurtzke Expanded Disability Status Scale (EDSS) and the Beck Depression Inventory scores were not related to subjective fatigue severity. In patients with MS and in patients with CFS, subjective fatigue severity was related to impairment in daily life, low sense of control over symptoms, and strong focusing on bodily sensations. In CFS, but not in MS, evidence was found for a relationship between low levels of physical activity and attributing symptoms to a physical cause and between subjective fatigue severity and physical activity. CONCLUSIONS Patients with MS experienced significant fatigue, which had a significant impact on daily functioning and was not related to depression on Expanded Disability Status Scale score. Psychological factors, such as focusing on bodily sensations and low sense of control play a role in the experience of fatigue in MS and CFS.