Application to Patients With Multiple Sclerosis and Systemic Lupus Erythematosus

symptom in a variety of medical and neurologic disorders. To facilitate research in this area, we developed a fatigue severity scale, subjected it to tests of internal consistency and validity, and used it to compare fatigue in two chronic conditions: systemic lupus erythematosus and multiple sclerosis. Administration of the fatigue severity scale to 25 patients with multiple sclerosis, 29 patients with systemic lupus erythematosus, and 20 healthy adults revealed that the fatigue severity scale was internally consistent, correlated well with visual analogue measures, clearly differentiated controls from patients, and could detect clinically predicted changes in fatigue over time. Fatigue had a greater deleterious impact on daily living in patients with multiple sclerosis and systemic lupus erythematosus compared with controls. The results further showed that fatigue was largely independent of self-reported depressive symptoms and that several characteristics could differentiate fatigue that accompanies multiple sclerosis from fatigue that accompanies systemic lupus erythematosus. This study demonstrates (1) the clinical and research applications of a scale that measures fatigue severity and (2) helps to identify features that distinguish fatigue between two chronic medical disorders. (Arch Neurol. 1989;46:1121-1123) T^atigue, long recognized as a major symptom in neurology and in med¬ icine, has been notoriously difficult to define or study as a distinct entity. Al¬ though it is nonspecific and highly subjective, fatigue is a prominent com¬ plaint in many disorders. In both mul¬ tiple sclerosis (MS) and systemic lupus erythematosus (SLE), for example, it may be the presenting symptom or a chronic and disabling problem.13 Re¬ cently, a chronic fatigue syndrome has been described in which fatigue is the overwhelming feature.4 Whereas in¬ terest in the role of fatigue in cognitive dysfunction and in distinguishing it from somatization disorders or affec¬ tive disorders has grown,5 our under¬ standing has been hampered by the lack of suitable techniques for its mea¬ surement. To facilitate research and patient treatment, we have developed a fatigue severity scale (FSS) that as¬ sesses disabling fatigue across two different clinical disorders. Use of this scale has helped elucidate the relation¬ ship between fatigue and depressive symptoms and has identified features of fatigue that might be characteristic of specific diseases.