Traumatic Brain Injury History Can Increase Veterans’ Long-Term Stroke Risk

US veterans with a history of traumatic brain injury (TBI) were found to have an increased long-term risk for stroke, according to study findings published in the journal Stroke.

Previous studies have shown the higher prevalence of TBI among military veterans; however, the association between TBI and long-term risk for stroke is unclear, especially among diverse populations.

Therefore, researchers sought to evaluate the risk for stroke among US veterans with TBI, as well as the effect of age, sex, race, ethnicity, and time since TBI diagnosis on this association.

Study participants were veterans who were aged 18 years and older and receiving care in the Veterans Health Administration (VHA) between October 2002 and September 2019. Veterans with TBI were matched 1:1 with those without TBI based on age, sex, race, and ethnicity.

Primary study outcome was any stroke; secondary outcomes were ischemic and hemorrhagic stroke.

A total of 306,796 veterans (mean age, 50 years; 91% men; 75% non-Hispanic White) were included in the analysis.

Compared with veterans without TBI, those with TBI were more likely to be current smokers and have medical and psychiatric comorbidities, including hypertension, hyperlipidemia, atrial fibrillation, posttraumatic stress disorder, and depression.

During a median follow-up of 5.2 years, 4.7% of the veterans with TBI had stroke, resulting in a total of 18,435 stroke events over a period of 1,787,238 person-years.

Risk for any stroke was 1.80-times greater among veterans with vs without TBI (P <.001). After adjusting for risk for death, veterans with vs TBI had a 1.69-fold (95% CI, 1.64-1.73) increased risk for any stroke. Similar observations were made for the association between TBI and ischemic and hemorrhagic stroke (hazard ratios [HRs], 1.56 and 3.92, respectively).  

Participants with TBI who were younger vs older and non-Hispanic Black vs other ethnicities had a lower risk for any stroke. Similar observations were made for ischemic and hemorrhagic stroke, based on age, race, and ethnicity. 

Compared with veterans without TBI, those with TBI with moderate or severe injury had a 2.02-fold (95% CI, 1.96-2.09) increased risk for any stroke and those with mild injury had 1.47-fold (95% CI, 1.43-1.52) increased risk for any stroke. The researchers noted similar patterns for ischemic and hemorrhagic stroke.

Based on time since diagnosis, the highest risk for any stroke occurred in the first year after injury (HR, 2.16; 95% CI, 2.03-2.29) and remained elevated for more than 10 years. Similar observations were seen with ischemic and hemorrhagic stroke.

Study limitations included the lack of inclusion of TBI or stroke events outside of the VHA system; specific details regarding history of prior remote TBI events or treatment not being captured; lack of generalizability to populations other than veterans and men; possibility of misdiagnoses of stroke; and potential residual confounding by socioeconomic status.

The researchers concluded, “[T]his study provides strong inferential evidence supporting the association of TBI with long-term risk for stroke,” which “[s]uggests that scrupulous attention to vascular risk factor modification and to other primary stroke prevention strategies among individuals with prior TBI may be important.”