The report is a product of the VA/HSR&D Evidence Synthesis Program.
Chronic Pain in Veterans and Servicemembers with a History of Mild Traumatic Brain Injury: A Systematic Review
Mild traumatic brain injury (mTBI) often resolves completely and quickly, without the need for much or any intervention. However, up to one-third of individuals who experience mTBI have a longer and/or more severe symptom course, and it is unclear why some individuals experience long-term sequelae from mTBI events while others experience complete resolution. Among Servicemembers and Veterans, in particular, it also is unclear whether symptoms and sequelae that are attributed to mTBI are due to the mTBI itself or, rather, are physical and mental health outcomes related to the same exposures (e.g., related to combat) that led to mTBI. Due to the common co-occurrence of mTBI with chronic pain and post-traumatic stress disorder (PTSD) among Veterans and Servicemembers, clinicians and researchers have described these comorbidities as the polytrauma clinical triad. In addition, because these complexities and additional clinical complications may be present when mTBI and pain are co-occurring, there is a need to better understand the epidemiology of these conditions, their potential impact on the risk of suicide and suicide-related behaviors, and the benefits and harms of interventions to treat chronic pain in this population.
Mild traumatic brain injury is often referred to as the “signature injury” among Servicemembers and Veterans of post-9//11 military operations. Approximately 413,000 SMs have experienced a traumatic brain injury (TBI) since the year 2000, and over 80% of those were classified as mild in severity.
This systematic review sought to identify the prevalence of chronic pain in Veterans and Servicemembers (SMs) with a history of mTBI, the risk of suicide, and the benefits and harms of interventions to treat chronic pain in this population. Investigators with VA’s Evidence Synthesis Program (ESP) Center in Portland, OR searched the literature, including multiple databases (Ovid Medline, Ovid EBM Reviews, Ovid PsycINFO, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, CINAHL, Scopus, Google Scholar, and Epistemonikos), clinical trial registries, and reference lists from inception through February 7, 2020. After reviewing more than 2,000 studies, investigators identified 27 articles (representing 26 studies) that reported chronic pain prevalence estimates in U.S. Veterans and Servicemembers with a history of mTBI, 1 study that examined suicide outcomes in the same population, and 3 studies that examined interventions for treatment of chronic pain in Veterans and Servicemembers with mTBI from any country.
Summary of Findings
Although pain is prevalent among Veterans and Servicemembers in general, the results of this review suggest that those with mTBI history – and especially those with comorbid mTBI and PTSD – experience pain at higher prevalence levels than those without a history of mTBI. Head pain (i.e., headaches or migraines; 23 studies) was the most common kind of chronic pain assessed in the studies included in this review, followed by back pain (10 studies), and arm, leg, and/or joint pain (9 studies). The one study examining suicide outcomes found that compared to those with mTBI history but relatively low rates of pain and other sensory diagnoses, Veterans with mTBI and high post-concussive symptoms, as well as mental health and pain comorbidities, were more likely to have been diagnosed with suicidal ideation or attempt. Among the studies that examined chronic pain interventions among Veterans and Servicemembers with mTBI, all three focused on treating headaches; two examined repetitive transcranial magnetic stimulation (rTMS), and one examined a type of neurotherapy. Further, all three studies were small and provided insufficient-strength evidence for these treatments.
Based on the existing research, precise estimates of the prevalence of pain conditions, locations, disability/interference, and severity are hampered by heterogeneity in study populations/samples, timing of pain ascertainment relative to individuals’ mTBI history, duration of study follow-up, and the methods used to identify, define, and operationalize both mTBI and chronic pain. Thus, the prevalence of chronic pain in the general population of US Veterans and Servicemembers, the impact of comorbid pain and mTBI on suicide risk in this potentially high-risk population, and the efficacy of pain therapies among those with comorbid mTBI and chronic pain remain largely unknown.
Research Gaps/Future Research
Future research that aims to understand chronic pain in a sample of all Veterans/Servicemembers with mTBI history, or of specified treatment-seeking Veterans/Servicemembers with mTBI history, would benefit from the assessment of pain chronicity (at least 3-6 months) and severity (moderate or higher). There also are recommended strategies for assessing chronic pain using administrative data, such as ICD diagnosis codes, that can improve the accuracy and comparability of prevalence estimates in these types of studies of chronic pain.
Future research also could compare responses to chronic pain interventions for participants with and without mTBI history to better understand whether mTBI results in a greater or lesser likelihood of benefit. Without such information, screening for presence and intensity of pain are likely warranted for Veterans and Service members with a history of mTBI so that they can be offered evidence-based treatment for chronic pain if needed.
O’Neil ME, Carlson KF, Holmer HK, Ayers CK, Morasco BJ, Kansagara D, Kondo K. Chronic Pain in Veterans and Servicemembers with a History of Mild Traumatic Brain Injury: A Systematic Review. Washington, DC: Evidence Synthesis Program, Health Services Research and Development Service, Office of Research and Development, Department of Veterans Affairs. VA ESP Project #05-225; 2020.
To view the full report, go to vaww.hsrd.research.va.gov/publications/esp/chronic-pain-mtbi.cfm (If you have intranet access, copy and paste the link into your browser.)
ESP is currently soliciting review topics from the broader VA community. Nominations will be accepted electronically using the online Topic Submission Form. If your topic is selected for a synthesis, you will be contacted by an ESP Center to refine the questions and determine a timeline for the report.
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