Mechanisms of heightened pain-related disability in Canadian Armed Forces members and Veterans with comorbid chronic pain and PTSD

Introduction: Posttraumatic stress disorder (PTSD) is highly comorbid with chronic pain in military personnel. Individuals with both conditions experience higher pain-related disability. The mechanisms contributing to increased painrelated disability in Canadian Armed Forces (CAF) members and Veterans with comorbid chronic pain and PTSD are poorly understood. Thus, this study examined the role of two potential mechanisms of comorbid PTSD and chronic pain that contribute to pain-related disability in military personnel: sensitivity to pain traumatization (i.e., the propensity of an individual to develop a traumatic stress-like reaction to pain [SPT]) and catastrophic thinking about pain. Methods: Study participants were 165 CAF members and Veterans with chronic pain. Participants completed an online survey assessing PTSD status, chronic pain status, and questionnaires assessing SPT, pain catastrophizing, and pain-related disability. A parallel multiple mediation analysis investigated whether SPT and pain catastrophizing mediated the relationship between PTSD and pain-related disability. Results: CAF members and Veterans with comorbid chronic pain and PTSD reported significantly greater pain-related disability compared to participants with chronic pain only. Both SPT and pain catastrophizing significantly mediated the relationship between PTSD and painrelated disability. Discussion: Findings suggest that PTSD may lead to greater pain-related disability in individuals with chronic pain by increasing individuals' susceptibility to becoming traumatized by their pain and by increasing their tendency to engage in catastrophic thinking about their pain. Targeting SPT and pain catastrophizing in the treatment of patients with comorbid PTSD and chronic pain may be an effective treatment strategy for reducing pain-related disability in patients.