Post-traumatic stress disorder moderates the relationship between trauma exposure and chronic pain

Background: Trauma exposure and post-traumatic stress disorder (PTSD) are risk factors for chronic pain. Objective: This study investigated how exposure to intentional and non-intentional traumatic events and PTSD are related to pain severity and outcome of treatment in chronic pain patients. Methods: We assessed exposure to potentially traumatizing events, psychiatric diagnosis with structured clinical interview, and pain severity in 63 patients at a secondary multidisciplinary pain clinic at the beginning of treatment, and assessed level of pain at follow up. Exposure to potentially traumatizing events and PTSD were regressed on pain severity at the initial session and at follow up in a set of multiple regression analysis. Results: The participants reported exposure to an average of four potentially traumatizing events, and 32% had PTSD. Exposure to intentional traumatic events and PTSD were significantly associated with more severe pain, and PTSD significantly moderated the relationship between trauma exposure and pain (all p < .05). The treatment programme reduced pain moderately, an effect that was unrelated to trauma exposure and PTSD. Conclusions: Trauma exposure is related to chronic pain in the same pattern as to mental disorders, with intentional trauma being most strongly related to pain severity. PTSD moderated the relationship between trauma exposure and pain. While pain patients with PTSD initially report more pain, they responded equally to specialist pain treatment as persons without PTSD.