A comparison of the relationship between depression, perceived disability, and physical performance in persons with chronic pain.

This study examined the relationships between self-report of depressive symptoms, perceived disability, and physical performance among 267 persons with chronic pain. Prior research has reported a relationship between depression and disability using self-report measures. However, self-report instruments may be prone to biases associated with depression as depressed persons with pain may have an exaggerated negative view of their level of function. In addition, we examined whether the relationship between depression and functional activity was mediated by physiologic effort (as measured by heart rate). The results indicated that self-report of depressive symptoms (using the Center for Epidemiological Studies-Depression Scale (CES-D)) was significantly correlated with self-report of disability on the Quebec Back Pain Disability Scale (QBPDS) and physical performance on the Progressive Isoinertial Lifting Evaluation (PILE). Regression analyses revealed that depression assessed by the CES-D significantly contributed to the prediction of QBPDS scores and PILE performance even when controlling for age, gender, site of pain, and pain intensity. The magnitude of the relationships between depression and self-report and functional activity were similar, suggesting that a self-report bias associated with depression is not responsible for an observed relationship between depression and disability. Physiologic effort partially mediated the relationship between depression and physical performance. The findings further highlight the importance of depression in the experience of chronic pain.