Assessing Trends in the Epidemiology of Concussions Among High School Athletes

OBJECTIVES: Approximately 300,000 youth athletes suffer a mild form of traumatic brain injury (TBI) known as a concussion annually while participating in organized athletics. Using data from the most recent 10-year period available, this study aimed to track national trends in high school sports-related concussion incidences over time, identify whether a particular sport predisposes athletes to a higher incidence of concussions, and evaluate the association between concussion occurrences and the enactment of TBI legislation that began in 2009. METHODS: Injury data for academic years 2005-2006 through 2014-2015 was collected from annual reports generated by the High School Reporting Information Online sports injury surveillance system, which prospectively captures injury data directly from athletic trainers at participating U.S. high schools. Relative proportions of total estimated concussions to total estimated injuries were compared using an injury proportion ratio (IPR) and corresponding 95% confidence intervals (CI). Concussion rate was defined as the number of concussions per 10,000 athlete-exposures (AEs, one athlete participating in one practice or competition), and rates were compared using a rate ratio (RR) and 95% CI. RESULTS: The overall number of concussions increased 2.2-fold (p<0.0001) between 2005-2006 and 2014-2015, and significant increases were also found in the overall concussion rate (RR=2.30, 95% CI [2.04-2.59]; p<0.0001) and the overall proportion of concussions (IPR=2.68, 95% CI [2.66-2.70]; p<0.0001). Players injured during the 2014-2015 school year were more likely to have sustained a concussion if they played girls soccer than if they played girls volleyball (IPR=1.32, 95% [1.30-1.35]; p<0.0001), girls basketball (IPR=1.35, 95% CI [1.33-1.37]; p<0.0001), or boys football (IPR=1.40, 95% CI [1.39-1.41]; p<0.0001) (Table 1). CONCLUSION: The overall rate and proportion of concussions increased significantly post-TBI law enactment, suggesting an association between the passage of TBI laws and concussion incidences. To our knowledge, this is the first study to report that concussions now account for a higher proportion of injuries in girls soccer than boys football. Currently, no state TBI laws address the sport- or gender-specific differences identified by this study. Future studies should focus on examining specific risk factors, developing targeted measures to reduce the number of preventable concussions, and developing diagnostic and treatment algorithms to protect young athletes and improve outcomes.