This study examined the contribution of pain and psychological distress to fatigue.
Methods: One-hundred and twenty-five adult Caucasian and Hispanic lupus patients participated in this study. Demographic data, patient- and physician-reported disease activity, as well as psychological functioning, were collected. Fatigue, pain, and vitality were measured using visual analogue scales as well as a subscale of the SF-36 questionnaire. Linear and hierarchical regression analyses were conducted. In the regression analysis, ethnicity was entered at the first step, followed by age, income and education at step 2, pain and disease activity measures at step 3, and psychological measurements at step 4.
Results: In the linear regression analysis, Caucasians reported more fatigue. Fatigue positively correlated with income, education, pain, patient-reported disease activity, helplessness, and depression, and negatively with internality, and the energy analysis mirrored the results of the fatigue analysis. In the first regression analysis, fatigue was the dependent variable. At step 1, Caucasians reported more fatigue. At step 2, no other demographic variables were significant. At step 3, pain and disease activity measures were significant when entered as a block; however, pain independently explained a large amount of variance. At step 4, psychological factors were significant as a block, with depression being the strongest predictor. In the second analysis, energy was the dependent variable. At step 1, Hispanics reported more energy. At step 2, demographic variables were not significant. At step 3, pain and disease activity were significant when entered as a block; however, only pain uniquely predicted energy. At step 4, psychological factors were significant as a block, with depression as the major contributor.
Conclusions: Both pain and depression were found to be strong predictors of fatigue, and negatively correlated with energy. Disease activity did not appear to play a significant role in lupus fatigue. These findings support the importance of managing depression and pain in order to reduce fatigue in patients with systemic lupus erythematosus.
Keywords: Fatigue; depression; pain.