Abstract
Although previous work has examined clinical outcomes in combat-deployed veterans, questions remain regarding how symptoms evolve or resolve following mild blast traumatic brain injury (TBI) treated in theater and their association with long-term outcomes. To characterize 5-year outcome in patients with nonmedically evacuated blast concussion compared with combat-deployed controls and understand what clinical measures collected acutely in theater are associated with 5-year outcome. A prospective, longitudinal cohort study including 45 service members with mild blast TBI within 7 days of injury (mean 4 days) and 45 combat deployed nonconcussed controls was carried out. Enrollment occurred in Afghanistan at the point of injury with evaluation of 5-year outcome in the United States. The enrollment occurred from March to September 2012 with 5-year follow up completed from April 2017 to May 2018. Data analysis was completed from June to July 2018. Concussive blast TBI. All patients were treated in theater, and none required medical evacuation. Clinical measures collected in theater included measures for concussion symptoms, posttraumatic stress disorder (PTSD) symptoms, depression symptoms, balance performance, combat exposure intensity, cognitive performance, and demographics. Five-year outcome evaluation included measures for global disability, neurobehavioral impairment, PTSD symptoms, depression symptoms, and 10 domains of cognitive function. Forward selection multivariate regression was used to determine predictors of 5-year outcome for global disability, neurobehavior impairment, PTSD, and cognitive function. Nonmedically evacuated patients with concussive blast injury (n = 45; 44 men, mean [SD] age, 31 [5] years) fared poorly at 5-year follow-up compared with combat-deployed controls (n = 45; 35 men; mean [SD] age, 34 [7] years) on global disability, neurobehavioral impairment, and psychiatric symptoms, whereas cognitive changes were unremarkable. Acute predictors of 5-year outcome consistently identified TBI diagnosis with contribution from acute concussion and mental health symptoms and select measures of cognitive performance depending on the model for 5-year global disability (area under the curve following bootstrap validation [AUCBV] = 0.79), neurobehavioral impairment (correlation following bootstrap validation [RBV] = 0.60), PTSD severity (RBV = 0.36), or cognitive performance (RBV = 0.34). Service members with concussive blast injuries fared poorly at 5-year outcome. The results support a more focused acute screening of mental health following TBI diagnosis as strong indicators of poor long-term outcome. This extends prior work examining outcome in patients with concussive blast injury to the larger nonmedically evacuated population.
Highlights
The long-term clinical impact of war-time mild blast-related traumatic brain injury (TBI) remains incompletely described.[1,2] Previous studies have been based largely on self-report and screening tools[3,4,5,6] to define TBI, rather than direct clinical assessments in cohorts identified at the time of injury and prospectively studied
Acute predictors of 5-year outcome consistently identified TBI diagnosis with contribution from acute concussion and mental health symptoms and select measures of cognitive performance depending on the model for 5-year global disability, neurobehavioral impairment, posttraumatic stress disorder (PTSD) severity (RBV = 0.36), or cognitive performance (RBV = 0.34)
Given the demographic differences between groups, all comparisons of clinical measures were adjusted for age, education, sex, rank, branch of service, in addition to subsequent concussion exposures followed by correction for multiple comparisons with final adjusted and corrected P values reported
Summary
The long-term clinical impact of war-time mild blast-related traumatic brain injury (TBI) remains incompletely described.[1,2] Previous studies have been based largely on self-report and screening tools[3,4,5,6] to define TBI, rather than direct clinical assessments in cohorts identified at the time of injury and prospectively studied. Few longitudinal studies have been completed in this population, largely restricted to the first year after exposure[19,22,23,24,25,26] or by serial evaluation only in the chronic stage.[27,28] One prior study compared predeployment, postdeployment, and more than 5-year follow-up; the study did not restrict inclusion to just mild TBI and did not discriminate between medically evacuated vs nonmedically evacuated cases.[29] The findings and prior body of literature motivate further research to better characterize risk factors that can be associated with long-term outcomes after mild TBI exposures in combat. Questions remain regarding how symptoms evolve or resolve following mild blast-related TBI treated in theater and how they are associated with the service member’s long-term trajectory
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