Physical and psychological correlates of fatigue and physical function: a Collaborative Health Outcomes Information Registry (CHOIR) study.

UNLABELLED: Fatigue is a multidimensional construct that has significant implications for physical function in chronic noncancer pain populations but remains relatively understudied. The current study characterized the independent contributions of self-reported ratings of pain intensity, sleep disturbance, depression, and fatigue to ratings of physical function and pain-related interference in a diverse sample of treatment-seeking individuals with chronic pain. These relationships were examined as a path modeling analysis of self-report scores obtained from 2,487 individuals with chronic pain from a tertiary care outpatient pain clinic. Our analyses revealed unique relationships of pain intensity, sleep disturbance, and depression with self-reported fatigue. Further, fatigue scores accounted for significant proportions of the relationships of both pain intensity and depression with physical function and pain-related interference and accounted for the entirety of the unique statistical relationship between sleep disturbance and both physical function and pain-related interference. Fatigue is a complex construct with relationships to both physical and psychological factors that has significant implications for physical functioning in chronic noncancer pain. The current results identify potential targets for future treatment of fatigue in chronic pain and may provide directions for future clinical and theoretical research in the area of chronic noncancer pain. PERSPECTIVE: Fatigue is an important physical and psychological variable that factors prominently in the deleterious consequences of pain intensity, sleep disturbance, and depression for physical function in chronic noncancer pain.