A causal model of depression for rehabilitation clients with musculoskeletal pain

The purpose of this study was to examine underlying factors of depression among individuals with chronic musculoskeletal pain, within the context of Lewinsohn, Hoberman, Teri, and Hautzinger's (1985) Integrated Model of Depression (IMD). Structural equation modeling (SEM) was used to test the plausibility of the hypothesized model based on the responses of 171 clients with chronic musculoskeletal pain in Canada. The model hypothesized that the existence of pre-injury psychopathology, negative perception of pain, high interference of daily activity, negative cognitive distortion (catastrophizing), high level of stress, and poor social and family support are directly related to depression. Positive pain coping is also related directly to positive perception of pain, reduced interferences, and positive social and family support, and indirectly to depression. Maximum likelihood estimation was employed to estimate the hypothesized model, and the comparative fit index (CFI) of .95 reflected a good fit model. Post hoc model modifications resulted in the addition of a path predicting stress from interferences and the deletion of four paths: “predicting perception of pain from pre-injury psychopathology,” “predicting depression from pre-injury psychopathology,” “predicting perception of pain from coping with pain”, and “predicting depression from pain.” The respecified model yielded a slightly improved CFI of .96. In general, both models appeared to support the applicability of Lewinsohn's IMD for individuals with chronic musculoskeletal pain. Contrary to the literature, pre-injury psychopathology was found to exert no direct significant influence on depression but was mediated by stress. Pain was not found to have a direct impact on depression. Coping with pain was not found to influence perception of pain. Coping also had no direct influence on depression but was mediated by interferences and social and family support. Perception of pain had no direct impact on depression, but it had a significant impact on interferences. Findings of the present study provided empirical support for the causal model of depression among clients with chronic musculoskeletal pain presented.