Objective: The relationship between fatigue and disease activity in systemic lupus erythematosus (SLE) has been questioned. We examined whether self-reported fatigue in patients with SLE is correlated with disease activity.
Methods: Consecutive patients with SLE at the University of Toronto Lupus Clinic were evaluated for disease activity using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). They were also evaluated for fibromyalgia (FM) by American College of Rheumatology criteria. One hundred patients completed the following health status questionnaires: the Fatigue Severity Score (FSS), Center for Epidemiologic Studies Depression Scale (CES-D), and Medical Outcomes Study Short Form Health Survey (SF-20). Disease activity was measured by the SLEDAI. Statistical correlations were made using the Spearman test.
Results: No significant correlation was found between FSS scores and SLEDAI (p = NS). Fatigue was found to be highly correlated with the presence of FM (p < 0.05) and depression (p < 0.01). In addition, fatigue was significantly associated with lower performance in all 6 domains of the SF-20 (p < 0.001); disease activity correlated with decreases in social function, mental health, and health perception areas of the SF-20. SLEDAI was not found to correlate with FM (p = NS).
Conclusion: Fatigue in patients with SLE does not correlate with disease activity. However, fatigue is correlated with FM, depression, and lower overall health status in this population. Fatigue is a manifestation of these conditions, which are commonly co-expressed in SLE, and may reflect a decreased overall coping ability in these patients, rather than active disease itself.