Frequency and impact of recurrent traumatic brain injury in a population-based sample.

The aim of this study was to determine the frequency, mechanism(s), and impact of recurrent traumatic brain injury (TBI) over a 1-year period. Population-based TBI incidence and 1-year outcomes study with embedded case-control analysis. All participants (adults and children) who experienced a recurrent TBI (more than one) in the 12 months after an index injury and matched controls who sustained one TBI within the same period were enrolled in a population-based TBI incidence and outcomes study. Details of all recurrent TBIs sustained within 12 months of the initial index injury were recorded. Each recurrent TBI case was matched to a case sustaining one TBI based on age (±2 years), gender, and index TBI severity. Cognitive ability, disability, and postconcussion symptoms (PCS) were assessed 1 year after the index injury. Overall, 9.9% (n=72) of TBI cases experienced at least one recurrent TBI within the year after initial index injury. Males, people <35 years of age, and those who had experienced a TBI before their index injury were at highest risk of recurrent TBI. Recurrent TBI cases reported significantly increased PCS at 1 year, compared to the matched controls (n=72) sustaining one TBI. There was no difference in overall cognitive ability and disability between the two groups. People experiencing recurrent TBIs are more likely to experience increased frequency and severity of PCS. Greater public awareness of the potential effects of recurrent brain injury is needed.