Barnes DE, et al. - In this propensity-matched cohort study of more than 350,000 veterans, researchers investigated the connection between traumatic brain injury (TBI) severity, loss of consciousness (LOC), and risk of dementia diagnosis in veterans. Findings revealed that, even mild TBI without LOC was related to more than a two-fold increase in the risk of dementia diagnosis in this patient population.

Methods

• This investigation included all individuals with a diagnosis of TBI in the Veterans Health Administration health-care system from October 1, 2001, to September 30, 2014, and a propensity-matched comparison group.
• Exclusion criteria included patients with dementia at baseline.
• Researchers identified cases of TBI through the Comprehensive TBI Evaluation database, which is restricted to Iraq and Afghanistan veterans, and the National Patient Care Database, which includes veterans of all eras.
• The severity of each TBI was based on the most severe injury recorded.
• Using Department of Defense or Defense and Veterans Brain Injury Center criteria, TBI was classified as mild without LOC, mild with LOC, mild with LOC status unknown, or moderate or severe.
• Using International Classification of Diseases, Ninth Revision codes, researchers identified dementia diagnoses during follow-up and medical and psychiatric comorbidities in the 2 years prior to the index date.
• Dementia diagnosis in veterans who had experienced TBI with or without LOC, as well as control participants without TBI exposure, were the main outcomes and measures analyzed.

Results

• The examination included 178,779 participants with a diagnosis of TBI in the Veterans Health Administration health-care system and 178,779 individuals in a propensity-matched comparison group.
• They found that veterans had a mean (SD) age of nearly 49.5 (18.2) years at baseline; 33,250 (9.3%) were women and 259,136 (72.5%) were non-Hispanic white individuals.
• Minor variations were reported between veterans with and without TBI.
• They found that 4,698 veterans (2.6%) without TBI developed dementia vs 10,835 (6.1%) of those with TBI.
• Adjusted hazard ratios for dementia were 2.36 (95% CI, 2.10-2.66) for mild TBI without LOC, 2.51 (95% CI, 2.29-2.76) for mild TBI with LOC, 3.19 (95% CI, 3.05-3.33) for mild TBI with LOC status unknown, and 3.77 (95% CI, 3.63-3.91) for moderate to severe TBI after adjustment for demographics, and medical and psychiatric comorbidities.