To investigate the relationship of fatigue severity to other clinical features in primary Sjogren’s syndrome (PSS) and to identify factors contributing to the physical and mental aspects of fatigue.
We identified 94 subjects who met the American-European consensus criteria for the classification of PSS. Fatigue was assessed with a VAS, the Fatigue Severity Scale (FSS) and the Profile of Fatigue (ProF.) Associations with fatigue was compared using multivariate regression.
Abnormal fatigue defined as a FSS score of greater than or equal to 4 was present in 67% of the patients. Pain, helplessness and depression were the strongest predictors of both FSS and the somatic fatigue domain of the ProF (Prof-S), both with and without adjustment for physiologic and serologic characteristics. Depression was associated with higher levels of fatigue; however, the majority of patients with abnormal fatigue were not depressed. Anti-Ro/SSA positive patients were no more likely to report fatigue than seronegative patients. The regression models explained 62% of the variance in FSS and 78% of the variance in Prof-S. Mental fatigue was correlated with depression and helplessness, but the model predicted only 54% of the variance in mental fatigue (Prof-M.).
Psychosocial variables are determinants of fatigue, but only partly account for it. While fatigue is associated with depression, depression is not the primary cause of fatigue in PSS. Investigation of the pathophysiologic correlates of physical and mental aspects of fatigue is needed to guide the development of more effective interventions.