Over the last decade, much research has been devoted to concussion among military personnel. Post-concussion symptoms after blast-related concussion are common, but it is unknown whether symptom reporting differs over time. This study's objective was to assess the relationship between time since injury and post-concussion symptom reporting. We conducted a retrospective review of existing records to identify service members who experienced blast-related concussion during deployment between 2007 and 2012 and who responded to a Post-Deployment Health Assessment (PDHA). The study population included 3690 military personnel grouped by time between injury and PDHA completion: 1-90 days (45.3%, n = 1,673), 91-180 days (33.0%, n = 1,216), or 181-365 days (21.7%, n = 801). Post-concussion symptoms assessed on the PDHA included headache, tinnitus, memory problems, concentration problems, difficulty making decisions, irritability, dizziness, and sleep problems. All post-concussion symptoms were higher for 91-180 days and 181-365 days after injury relative to 1-90 days, with the exception of dizziness. After adjustment for loss of consciousness, mental health comorbidity, and other covariates, the odds of reporting three or more post-concussion symptoms were significantly higher in those who completed the PDHA 91-180 days (odds ratio: 1.29; 95% confidence interval: 1.09-1.51) or 181-365 days after injury (odds ratio: 1.33; 95% confidence interval: 1.09-1.61), compared with the 1-90 days group. These findings suggest that refinements to in-theater medical care may be needed to reduce post-concussion symptom burden and improve the prospect of concussion recovery.
Keywords: combat; concussion; mild traumatic brain injury; military; post-concussion symptoms.