Informing Our Understanding of Chronic Pain Epidemiology, Extreme Outcomes, and Healthcare Access Among Persons With Hospitalized TBI: A NIDILRR and VA TBI Model Systems Collaborative Project

THE PRESENCE OF COMORBID CONDITIONS among persons with traumatic brain injury (TBI), with headache as the most frequent condition,1 is associated with worsened outcomes in chronic phases. Recent work has highlighted that TBI in the presence of comorbid chronic pain is significantly associated with greater disability, lower levels of community reintegration, and poor psychological health (depression and decreased satisfaction with life).2–4 Given the limited treatment options for reversing the morbidity of TBI, addressing chronic pain in the aftermath of TBI has the potential to improve neurologic and psychosocial outcomes as well as overall quality of life.5–7 Pain can result from a variety of concurrent injuries after TBI including soft tissue or musculoskeletal pain (eg, wounds, sprains, burns, fractures), neuropathic sources (eg, spinal cord injury and peripheral nerve injury), and pain related to the TBI itself (eg, headache, spasticity, other neuropathic/central pain, and heterotopic ossification). There is a paucity of research investigating the overlap in these pain conditions for those with comorbid chronic pain and TBI. Individuals with TBI are a population of concern in the current focus on opioid addiction in the United States. There is evidence of high opioid use by individuals with TBI to manage pain after trauma both during and after hospitalization.7–9 Therefore, more in-depth knowledge of chronic pain is essential. We included assessment of opioid use and misuse to help better understand how opioid use interacts with multimorbidity, TBI indices, and overall outcomes that may inform changes in clinical practice. Such changes could lead to reduction in negative outcomes from pain and substance misuse in a population at risk for both.2,10–12 The National Institute on Disability, Independent Living and Rehabilitation Research (NIDILRR) TBI Model Systems Collaborative Grant mechanism funded a multicenter study addressing key gap areas in our understanding of TBI and chronic pain. Leveraging the TBI Model Systems National Database, the largest longitudinal study of TBI in the world (www.tbindsc.org),13 this study co-enrolled persons in the NIDILRR and VA TBI Model Systems14 (>3800) from 18 centers across the United States. Two of 3 study aims addressed epidemiology, associations, and extreme outcomes. A cohort of providers (n = 63) were enrolled in the third aim using a mixed-methods design to understand determinants (facilitators and barriers) to chronic pain care. The rich data associated with the study have generated 4 manuscripts15–18 to date, with 10 more included in this topical issue. The valuable data associated with the mixed-methods approach of this project are being archived for future use at the Inter-university Consortium for Political and Social Research (ICPSR). Leveraging the largest moderate-to-severe TBI cohort to date, the first article in this special issue describes the prevalence of chronic pain (46% current chronic pain; 14% past chronic pain), which remains high across all follow-up intervals postinjury (from 1 to 30 years).19 This article suggests that for those with current chronic pain, multimorbidity is common with a median of 4 pain locations and that the most common treatments utilized were medical in nature. The second article highlights that after adjusting for traditional TBI covariates, the presence of comorbid current chronic pain is associated with greater severity of psychological health distress (posttraumatic stress, anxiety, and depressive symptoms) as well as poorer sleep quality across both military and civilians alike.20 Findings support the importance of access to care for these conditions to improve overall outcome after TBI. The next series of articles used a methodology from precision medicine, which defines persons experiencing extreme outcomes (best and worst) relative to disease progression, severity, or treatment responsiveness.21 This series of articles describes varied risk factors and modifiable covariates associated with extreme responses on pain interference and perceived improvement.22,23 We also used a similar methodological approach to examine extreme phenotypes on a stakeholder prioritized domain of psychosocial outcome.24 This novel approach provides a potential pathway to better characterize the experience of pain as well as to compare interventions in those who have chronic pain after TBI. With a majority of the epidemiologic cohort reporting chronic pain in the decades post-TBI, a dearth of information exists regarding access to high-quality chronic pain care. Informed by a conceptual framework for accessing healthcare, 2 articles describe the determinants to identifying, perceiving, seeking, reaching, and utilizing high-quality healthcare for chronic pain.25,26 These articles report the perspectives of a national provider cohort that completed semistructured interviews that revealed 48 determinants to accessing chronic pain healthcare. Identification of 33 facilitators highlighted successful practices to improve access, including tailoring treatment to the unique needs of persons who have had a TBI––discussed by 100% (saturation) of the sample. The primary challenge to delivering chronic pain healthcare was the cognitive disability that persons with TBI experience (67% saturation) and the likely contribution to high rates of noncompliance and poor follow-up in receipt of chronic pain healthcare (62% saturation).26 Results will inform future interventions at the patient, system, and policy levels of healthcare. These interventions can be tailored to healthcare settings (VA, civilian) and types of providers (rehabilitation therapists, psychologists, and medical). With the large number of determinants identified, Haun and colleagues27 engaged stakeholders to identify implementation strategies to overcome the leading barriers to accessing chronic pain care. The 3 articles combined will inform translational work to improve access to chronic pain healthcare services for those with greater TBI morbidity. Finally, 2 supplemental articles examine (1) potential predictors of headache both early and later after injury and the relationship of headache to psychosocial factors,28 and (2) the interaction of opiate misuse and marijuana use on behavioral health outcomes.29 These articles highlight 2 primary areas of interest for those with TBI, their families, and healthcare providers who work with this population. The first provides important evidence for the need to consider risk factors during clinical evaluation and the importance of addressing headaches, given their impact on psychosocial outcomes. The second provides information on the prevalence of opiate misuse and marijuana use as well as the negative association between substance use and behavioral outcomes. Further work is needed to develop clinical practice guidelines, but the initial step in better understanding the multiple causes of chronic pain and how individuals differ in their response to pain significantly adds to our understanding of the experience of chronic pain after TBI. Advancements in treatment of chronic pain in this population may allow amelioration of functional disability by using protocols that are individualized to treatment responder subtypes. This precision will, in turn, lead to a decrease in pain interference. Negative side effects of analgesic medications and interventional treatments will be minimized by identifying patients who are likely to exhibit optimal responses to such approaches. Ultimately, findings from this large multicenter study can inform policy, healthcare infrastructure, and care delivery of chronic pain management after TBI. This topical issue also highlights the basic (precision medicine), clinical, health services, and implementation science research that is needed to inform management of chronic pain in persons with TBI.