A study of fatigue in systemic lupus erythematosus. Fifty-nine patients with systemic lupus erythematosus were evaluated by questionnaires, histories, physical examinations and routine laboratory studies in order to better understand their fatigue. The fatigue severity scale (scored from 1 to 7) was used to measure fatigue and yielded a mean score +/- SD of 4.6 +/- 1.5. Fifty-three percent of the patients reported that fatigue was their most disabling symptom. Although perceived as severe, the symptom of fatigue did not correlate significantly with any of the laboratory measures. However, there was a significant correlation between fatigue and the physician's rating of disease activity. Fatigue also correlated significantly with depression which accounted for 21% of the variation in fatigue scores. 