The Synergistic Effect of Acute Traumatic Brain Injury and Spinal Cord Injury on the Development of Chronic Pain: A Populational Cohort Study on Neurotrauma Patients in Canada.

The impact of concomitant traumatic brain injury (TBI) and spinal cord injury (SCI) on the development of problematic chronic pain has never been studied. We hypothesized that concomitant TBI increases the rates of problematic chronic pain outcomes in SCI individuals. To examine the association between concomitant TBI-SCI (as opposed to isolated TBI or SCI) and the development of problematic chronic pain outcomes, including referral to a specialized pain clinic or long-term usage of opioids or other chronic pain medications. A retrospective observational cohort study on 18,861 neurotrauma patients from prospective governmental populational databases from the province of Quebec, Canada (population ∼8 million) was conducted. The main independent variable was the nature of neurotrauma sustained at the time of the accident: TBI only versus SCI only versus concomitant TBI-SCI. Problematic chronic pain was defined as (1) receiving a formal diagnosis of chronic pain, (2) using significant amounts of opioids, or (3) receiving a referral to a chronic pain clinic. Out of the all the included patients, 16,472 (87%) had TBI only, 1528 had TSCI only (8.1%), and 861 (4.6%) had concomitant TBI-SCI diagnosis. At the group level, patients with concomitant TBI-SCI presented markedly higher use of opioid/chronic pain medication than patients with SCI or TBI only (15.3% vs. 8.5% vs. 0.5%; P <.001). At the multivariate level, the nature of neurotrauma sustained remained significantly associated with all 3 outcomes that were used to define problematic chronic pain. Finally, a synergistic effect between SCI and TBI was confirmed for the development of chronic use of opioids and other pain medications (odds ratio [OR] 1.92; P <.001). This study supports a synergistic effect of TBI and SCI for the development of chronic use of opioids and other pain medications. Clinicians should be aware of potential underlying TBI in SCI patients in order to address potential chronic pain issues after neurotrauma.