Dimensions of fatigue in systemic lupus erythematosus: relationship to disease status and behavioral and psychosocial factors.

OBJECTIVE: To characterize the experience of fatigue in patients with systemic lupus erythematosus (SLE) using a multidimensional assessment and to delineate contributors to physical and mental dimensions of fatigue.
METHODS: Fatigue in 130 women with SLE was assessed using the Multidimensional Fatigue Inventory (MFI-20). Participants completed standardized questionnaires assessing sleep quality, depressed mood, social support, and leisure-time physical activity. A clinical examination determined disease activity, cumulative damage, and whether patients fulfilled American College of Rheumatology criteria for fibromyalgia (FM). A series of hierarchical multiple regressions were computed to identify contributors to physical and mental fatigue.
RESULTS: Patients scored high on all 5 MFI-20 fatigue dimensions, with general fatigue and physical fatigue having the highest scores. A hierarchical multiple regression showed that greater disease damage and disease activity, the presence of FM, depressed mood, sleep disturbance, and less participation in leisure-time physical activity contributed to higher physical fatigue scores. The results of the second model found depressed mood to be the strongest determinant of mental fatigue. Disease-related variables were not associated with mental fatigue.
CONCLUSION: Fatigue in SLE is multidimensional and multidetermined, with physical and mental aspects likely having different etiologies. A multidimensional assessment of fatigue in SLE is needed to tailor and optimize interventions aimed at alleviating fatigue.