Combat-related concussion increases odds of long-term disability in Veterans in a prospective 10-year study
By Lori Mae Yvette Calibuso Acob. This article was initially published in our Concussion Update newsletter; please consider subscribing.
Dr. Mac Donald et al. conducted a 10-year prospective study of veterans deployed to Iraq and Afghanistan to determine the trajectory of disability within this population and identify which subset of the population is most at risk. Their study, published in the Journal of Head Trauma Rehabilitation, demonstrated that veterans who sustained a concussion in combat had “very high odds of poor long-term outcome trajectory.”
Characteristics of veterans at higher risk of poor long-term outcomes include: sustaining a concussion in combat, being of younger age at the time of injury, having lower education, and being enlisted in the Army. Mac Donald and her team are hopeful that these findings will lead to more aggressive treatment strategies for servicemembers meeting these characteristics.
The team enrolled service members with combat-related concussions (exposed group) and those with no brain injuries (control group), resulting in a cohort of 475 veterans. Next, the researchers divided the exposed group into two groups: 1) concussive blast TBI “blast TBI” and 2) combat-related concussion not from blast “non-blast-TBI.” They similarly divided the control group into two subgroups: 1) no history of blast exposure “non-blast-control” and 2) history of blast exposure “blast-control.”
Throughout the study, the team followed up with the veterans every six months to perform a Glasgow Outcome Scale Extended (GOS-E) evaluation via phone. GOS-E is used to assess the disability and recovery of veterans after TBI exposure. After ten years, the GOS-E scores were analyzed for common characteristics to create three trajectory groups: good recovery, upper-moderate disability, and lower-moderate disability. (The team also identified death as a trajectory group. However, this group had very few members and was not used in further analysis).
The researchers found that service members who sustained a blast-TBI in combat were 49 times more likely to have a worse disability trajectory than the non-blast control group (combat history, no TBI, and no exposure to blasts). Service members who sustained a non-blast TBI in combat were 37 times more likely to have a worse disability outcome than non-blast controls. Even those service members who did not sustain a brain injury but were exposed to blasts “were 5 times more likely to be in these worse disability categories compared with non-blast-controls.” Furthermore, the team noticed a downward trend for veterans in the ‘good recovery’ trajectory, starting around the 8-year mark post-deployment. In other words, the outcomes of veterans in the ‘good recovery’ trajectory decline after about eight years of tracking.
Limits of this study include the inability to control for the heterogeneity of treatment that the veterans received, lack of pre-deployment information, and little representation for female service members. However, Mac Donald and her team are hopeful that these findings will aid in the development of more aggressive treatment strategies in veterans, especially those meeting the high-risk criteria, following deployment.