Decreasing numbers of adolescent boys participating in high school tackle football, as reported by news outlets, may be because of increasing concerns about football-associated health risks, including progressive chronic traumatic encephalopathy.1-3 Evidence of an association between decreasing participation of adolescent boys in high school tackle football and news reports about traumatic brain injury has not been specifically examined.
Annual high school football participation data for the fall seasons from 2001 to 2016 were obtained from the National Federation of State High School Associations.4 Annual number of news reports from January 1, 2001, to December 31, 2016, was obtained from LexisNexis Academic database,5 using inclusive index search terms American football and brain injury (including concussion) on August 29, 2017. All the data used in this study are deidentified, publicly available data and do not consist of research using human patients.
Visual inspection of participation data suggested an inflection point between the 2008 and 2009 seasons. Linear trends over time and changes in linear slopes were determined using linear and temporal autocorrelation-robust interrupted time series regression. Estimates of the predicted number of participants in 2016, if prior trends had continued, were generated using linear regression with data from the 2001 season to the 2008 season. For evaluation of regression model coefficients, unpaired t tests were used and 2-sided, P < .05 defined statistical significance. All analyses used Stata (version 15; StataCorp).
From the 2001 to 2016 seasons (Figure, A), annual participation by adolescent boys in 11-player high school tackle football initially increased from 1 023 142 in the 2002 season to a peak of 1 112 303 in the 2008 season (an increase of 8.65%), and subsequently decreased by 4.93% to 1 057 407 in the 2016 season. The difference in the annual change in participation numbers from the 2009 to 2016 seasons, compared with the preceding 2001 to 2008 seasons, was statistically significant (P < .01), and the decrease in participation observed during the latter period (2009 to 2016 seasons) was also statistically significant (P < .01).
During the same 16-year period (Figure, B), the annual number of news reports about tackle football and brain injuries was steady from 2001 to 2008, then markedly increased from 2009 to 2016. The annual change in the number of news reports from 2001 to 2008 was statistically different from that from 2009 to 2016 (P = .01), and the increase observed in the latter years (2009 to 2016) was statistically significant (P < .01).
In contrast to the changing pattern of participation in football, overall participation in high school athletics for adolescent boys (Figure, C) increased from the 2001 to 2002 school year to the 2016 to 2017 school year (P < .01).
Participation by adolescent boys in 11-player tackle football shifted from an annual increase to, starting in 2009, an annual decrease. The timing of this shift coincides with an increase in the number of news reports regarding American football and brain injury. The decrease in participation contrasts with the increasing trend of overall participation by adolescent boys in high school athletics. Although we cannot exclude factors other than concerns about concussions in athletes as driving the decrease in participation, the timing of this shift is suggestive.
The combination of research and news reports may be propelling an epidemiologic shift in behavior with potentially important public health consequences. Given the 4.93% decrease from peak participation in the 2008 season to the 2016 season, compared with the preceding increase of 8.65% from the 2001 to the 2008 season, the 2016 participation numbers may actually reflect 184 133 fewer tackle football players than if the previous upward participation trend had continued. With an estimated incidence rate of concussions per athlete per season between 0.03666 and 0.07847 (assuming a season comprises 10 games and 60 practices), in 2016, there may have been between 6739 to 14 436 fewer concussions attributable to participation in high school football.
If the concerns that the development of chronic traumatic encephalopathy could be initiated with concussion exposure limited to high school tackle football are warranted, this decrease could have public health repercussions. More attention should be devoted to understand the factors driving this behavioral shift.
Corresponding Author: Chris Feudtner, MD, PhD, MPH, Roberts Center for Pediatric Research, Children's Hospital of Philadelphia, University of Pennsylvania, 2716 South St, Philadelphia, PA 19146-2305 (feudtner@email.chop.edu).
Accepted for Publication: November 6, 2017.
Published Online: March 12, 2018. doi:10.1001/jamapediatrics.2017.5242
Author Contributions: Dr Feudtner had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: All authors.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: All authors.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Feudtner.
Administrative, technical, or material support: Feudtner.
Study supervision: Feudtner.
Conflict of Interest Disclosures: None reported.
Additional Contributions: The authors thank Mr Schall for his assistance with the LexisNexis database search. Mr Schall was not financially compensated.
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