An examination of the structural link between post-traumatic stress symptoms and chronic pain in the framework of fear-avoidance models

Background: The tendency to respond with fear and avoidance can be seen as a shared vulnerability contributing to the development of post-traumatic stress disorder (PTSD) and chronic pain. Although several studies have examined which specific symptoms of PTSD (re-experiencing, avoidance, emotional numbing and hyperarousal) are associated with chronic pain, none has considered this association within the framework of fear-avoidance models. Methods: Seven hundred fourteen patients with chronic musculoskeletal pain were assessed. Of these, 149 patients were selected for the study based upon the following inclusion criteria: exposure to a traumatic event before the onset of pain (with scores equal to or higher than 8 points on the fear and hopelessness scales of the Stressful Life Event Screening Questionnaire Revised) and scores equal to or higher than 30 on the Davidson Trauma Scale. Results: Structural equation modelling was used to test the association between PTSD symptoms and pain outcomes (pain intensity and disability) using the mediating variables considered in the fear-avoidance models. The results show that emotional numbing and hyperarousal symptoms, but neither re-experiencing nor avoidance, affected pain outcome via anxiety sensitivity (AS), catastrophizing and fear of pain. PTSD symptoms increased the levels of AS, which predisposes to catastrophizing and, in turn, had an effect on the tendency of pain patients to respond with more fear and avoidance. Conclusions: This study provides empirical support for the potential role of PTSD symptoms in fear-avoidance models of chronic pain and suggests that AS is a relevant variable in the relationship between both disorders.