A population-based study of repetitive traumatic brain injury and mortality

Traumatic Brain Injury (TBI) is a significant public health problem. Studies of athletes suggest that repetitive TBI (RTBI) may have a cumulative effect on outcomes, although this has not been well explored in the general population. Negative health outcomes have been observed in persons with only one head injury. However, specific outcomes after the first TBI may be compounded or differ for persons who sustain RTBI. The overarching goal of this study was to investigate RTBI in a representative sample of persons discharged from an acute care setting with TBI. This study addresses the following four specific aims: (1) To estimate and compare the hazard of a second TBI event in a cohort of TBI hospital discharges as a function of TBI severity. (2) To estimate and compare the hazard of mortality in a cohort of TBI hospital discharges as a function of RTBI. (3) To assess and compare outcomes (behavioral, cognitive complaints, and alcohol consumption) as a function of RTBI in a cohort of persons with TBI interviewed at one year after injury. (4) To assess and compare the effect of pre-existing health conditions on the risk of RTBI in a cohort of persons with TBI.;This study followed a retrospective cohort design in which outcomes gleaned from a cohort of TBI hospital discharges were analyzed for outcomes. This study used data from the South Carolina Traumatic Brain Injury Follow-up Registry (SCTBIFR), a population-based statewide stratified random sample of 4,915 in-state TBI hospital discharges from January 1, 1999 through June 30, 2002. Medical records of the sample were reviewed, and telephone interviews were completed at one year post-injury on 57% of eligible participants. Information on prior TBIs was retrospectively gathered back to 1996, and also persons sampled were followed through December 31, 2005 for subsequent events of TBI and/or mortality. We found that persons with pre-existing epilepsy/seizure disorder were more likely to experience RTBI than persons without preexisting epilepsy/seizure disorder, and in fact was more strongly associated with RTBI than previous TBI severity. We did not find relationships between RTBI and any of the outcomes (cognitive complaints, behavioral, or heavy drinking). These results may have been biased by the lack of outcome information in persons who needed a proxy respondent. We also did not find a relationship between RTBI and mortality. Our study did not support the theory of cumulative effects of RTBI on health outcome. However, further study should be conducted using clinical measures of health outcome.