Self efficacy as a mediator of the relationship between pain intensity, disability and depression in chronic pain patients.

To clarify the relationships between physical, and psychosocial components of chronic pain, a path analytic model was tested conceptualizing self efficacy as a mediator of disability. In turn, disability was hypothesized to mediate depression. This model could help explain the circumstances under which disability develops and why so many chronic pain patients become depressed. Questionnaires from 126 chronic pain patients (without prior depression) were reviewed from three pain clinics. Hypothesized and alternate models were tested using separate regression equations to identified models which best fit these data. Regression analysis supported that self efficacy partially mediates the relationship between pain intensity and disability. This model accounted for 47% of the explained variance in disability (P < 0.001). Six additional variables that were significantly related to disability in preliminary analysis, added to the explained variance in disability (R2 = 0.56), with gender and pain location paths remaining significant. In separate regression analyses, disability was found to partially mediate the relationship between pain intensity and depression (b = 0.47-0.33). This model accounted for 26% of the explained variance in depression. The addition of self efficacy to this model supported it as a stronger mediator (R2 = 0.32), and suggested that support for disability as a mediator of depression was a spurious finding. Both pain intensity and self efficacy contribute to the development of disability and depression in patients with chronic pain. Therefore, the lack of belief in ones own ability to manage pain, cope and function despite persistent pain, is a significant predictor of the extent to which individuals with chronic pain become disabled and/or depressed. Nevertheless, these mediators did not eliminate the strong impact that high pain intensity has on disability and depression. Therefore, therapy should target multiple goals, including: pain reduction, functional improvement and the enhancement of self efficacy beliefs.