Military personnel who sustained combat-related traumatic brain injury in Iraq or Afghanistan are at a significantly higher risk of long-term disability than other groups of veterans, new research reveals.
Those who served in the Iraq or Afghanistan conflicts are at up to 49 times greater risk of long-term outcomes, the study showed.
“We found very high odds of being on a trajectory of worse long-term outcome for those who sustained a concussion in combat and were younger at the time of exposure, well above the risk of deployment alone,” said Dr Christine L. MacDonald, of University of Washington School of Medicine, Seattle, who led the study.
And based on the experience of World War I, World War II and the Vietnam War, the true impact of disability among those injured in Iraq and Afghanistan “is likely not to be felt for decades,” the study added.
The researchers said they hope their findings can aid in identifying veterans at high risk of long-term disability after sustaining a combat-related TBI.
Dr MacDonald and colleagues analysed ten years of follow-up data on veterans deployed to Iraq or Afghanistan, drawn from the Evaluation of longitudinal outcomes in mild TBI Active-Duty Military and Veterans (EVOLVE Study).
“Our study is unique, as we were able to evaluate these patients at the time of their injuries and have carefully followed them ever since,” Dr MacDonald said, adding that the veterans have now been followed up every six months for ten years.
Disability in combat-deployed cohorts was compared for 236 veterans with concussive ‘blast TBI’ and 143 veterans with no blast exposure.
The study also included exploratory groups of 54 deployed veterans who experienced blast exposure but not TBI and 42 ‘non-blast TBI’ veterans with other causes of concussion.
Using a technique called latent class growth analysis, Dr MacDonald and colleagues defined four trajectory groups with similar levels and patterns of outcomes.
The researchers were then able to identify the characteristics of veterans in these trajectory groups: good recovery, upper moderate disability, lower moderate disability, and death.
Sustaining a concussion during deployment was by far the most important factor determining long-term outcome, the research found.
Compared to those with no blast exposure, the odds of being in the worse disability trajectories were 49 times higher for service members with blast TBI and 37 times higher for those with non-blast TBI.
Even veterans who had blast exposure without concussion were five times more likely to be in worse disability categories, compared to those with no blast exposure.
Other risk factors for worse long-term outcome trajectories were younger age at the time of injury and enlistment status at the time of deployment.
All identified risk factors remained significant after accounting for demographic factors and subsequent brain injury exposure over the decade following deployment.
The findings confirm that veterans with blast- or non-blast TBI sustained in combat have higher odds of worse disability trajectories over the long-term.
Age and enlistment status at the time of deployment also have a significant impact on 10-year outcomes.
Dr MacDonald and co-authors conclude: “We believe these findings help inform targeting of more aggressive treatment strategies in service members meeting this profile of greatest risk following deployment to aid in reducing the high public health burden identified with prior conflicts.”
