The overall response rate (60.4%) was lower than the previous survey (92.3% in McCrea et al,10 P < 0.001). For this reason, predictors of nonresponse were explored using 2 approaches: (1) comparison of respondents and nonrespondents and (2) comparison of respondents to the targeted population on variables collected at preseason baseline evaluations. Fortunately, because we only targeted athletes who had completed a prior baseline testing protocol, we had a host of demographic, historic, and other information on the population from which to examine patterns of nonresponse.
Specifically, we compared groups on gender, race, age, level of competition (high school, college), sport, history of prior concussions, grade point average (GPA), estimated general intellectual ability, Wechsler Test of Adult Reading scale score (WTAR), socioeconomic status (SES) (using a Hollingshead rating system), baseline (Sport Concussion Assessment Tool 3) symptoms, and self-reported ratings of emotional distress (Brief Symptom Inventory-18 global severity index). Demographics and other characteristics were statistically equivalent between respondents, nonrespondents, and the entire population on the majority of measures. However, football players were more heavily represented in the survey sample, 63.1% (95% confidence interval = 59.6%-66.5%) versus the population, 55.6% (53.7%-59.2%). In contrast, men's lacrosse players were less well represented in the respondent sample, 0.3% (0.0%-1.0%) in comparison to the population 3.2% (2.4%-4.4%). These differences could be because of the highly organized nature of the men's football programs at the surveyed institutions and the fact that, because of the timing of the sport seasons and onset of this survey study, lacrosse players were only recruited through e-mail (a survey modality known to reduce response rates).36 Overall nonresponse appeared relatively unsystematic, suggesting that the data summarized below reflect reasonably unbiased estimates of the opinions of the target population.
Questionnaire results and comparisons to the original are displayed in Table 1. Reported history of concussion (before the most recent sport season) was similar to previous levels (31.1% vs 29.9% in 1999-2002; P = 0.730). Concussion rates for the most recent season were also similar to previous levels (16.6% in 2013 vs 15.3% in 1999-2002; P = 0.558). In this study, males were significantly more likely to report a history of prior concussion than females, χ2(1) = 6.74, P = 0.009, but males and females were equally likely to report having sustained a concussion in the surveyed season (P = 0.396). Athletes with a history of concussion were more likely to report that they sustained a concussion in the most recent sport season, χ2(1) = 24.08, P < 0.001. Male and female soccer players were equally likely to report a history of concussion (P = 0.401) and a concussion during the most recent season (P = 0.180). College athletes were more likely to have a history of concussion over high school athletes, χ2(1) = 19.88, P < 0.001, but no difference was noted for concussion during the most recent season (P = 0.278). Household SES and WTAR standard score were not associated with remote history or recent-season concussion (P > 0.05, d = 0.02, 0.06) but those with a lower GPA were more likely to have a history of concussion (t (769) = 3.15, P = 0.002, d = 0.23).
Table 1 summarizes the concussion rates and reporting behaviors for this study, with data from the prior 1999 to 2002 survey included for comparison. Among those who sustained a concussion in the most recent season, 78.6% reported it to someone. Reporting rates were significantly higher than previously, even when considering more comparable groups (ie, high school football), with 70.6% reporting in 2013 versus 47.3% in 1999 to 2002; χ2(1) = 6.50, P = 0.011. Of all respondents in 2013, 92.2% of those that reported their concussion told their athletic trainer. For the 2013 and 1999 to 2002 high school football groups, athletes who reported their concussion to someone most frequently told (1) an athletic trainer (87.5% and 76.7%, respectively; P = 0.248) and (2) a coach (62.5% and 38.8%; P = 0.034). Totals may exceed 100%, as respondents could select that they reported to multiple individuals. Although the overall pattern of reporting (across trainers, coaches, parents, etc.) was similar in the current and past surveys, respondents in this study were more likely than those in 1999 to 2002 to inform their coaches, χ2(1) = 4.46, P = 0.034. Level of play (high school vs college), sex, household SES, and WTAR standard score was not associated with whether or not athletes reported their concussions (P > 0.05, d = 0.05-0.08), but those with a lower GPA were less likely to report a concussion (t (96) = −2.18, P = 0.032, d = −0.49).
Of all respondents in this study, the most common reasons not to report concussions were that they did not think their injuries were serious enough (71.4%) and they did not want to be pulled from game/practice (61.9%). Comparing the high school football players in this study with the prior study sample, athletes were more likely to cite “did not want to be pulled from game/practice” as a reason for not reporting, 70% currently versus 36.1% previously; χ2(1) = 4.40, P = 0.036. Other reasons for not reporting were comparable between the 2 groups (P ≥ 0.05).
Awareness and Effect of Wisconsin State Law on Concussion Reporting
Results of the questions about the Wisconsin state law are provided in Table 2. Analyses of these questions excluded collegiate athletes, because the law does not pertain to college or university athletic programs.31 In addition to the 37 high school respondents with a concussion this season, 298 respondents without a concussion responded to these questions and their responses were interpreted as indicating how their awareness of the law would have affected their reporting had they sustained a concussion this season. Overall, 59.5% of high school students were aware that Wisconsin has a state law regarding sport-related concussions. No differences were noted by sport, sex, WTAR standard score, GPA, or household SES regarding knowledge of the law for all respondents. Of respondents aware of the law, 55.1% said it would make them more likely to report a concussion, 37.4% stated it would make no difference, and 7.5% said it would make them less likely to report. Males were more likely than females to state that the law would make it more likely for them to report a concussion, χ2(3) = 9.95, P = 0.019. Football players were more likely to state the law would make it more likely to report than women's soccer players, χ2(3) = 9.17, P = 0.027, but no difference was noted between football and men's soccer, or men's soccer and women's soccer (P > 0.05).
This survey study demonstrated that self-reported concussion rates have not changed significantly since the prior survey conducted approximately 14 years ago, but the rate at which athletes report suspected concussions has increased significantly (78.6% in 2013, vs 47.3% in the 1999-2002). This suggests that the apparent rising incidence documented by other studies13,26,27 is probably best explained by changes in athletes' reporting decisions rather than true increases in injury rates.
The percentage of potential concussions that were unreported (21.4%) in this sample fell somewhat in between estimates from other studies (which ranged from 11% to 55%),11,19–23 but the broad range from other literature is likely because of the year/time in which the studies were conducted, the sports targeted, and the variable durations of time during which athletes were asked to report injuries. Given that we compared the data from this study with the data on an equivalent measure from comparable samples of athletes within the same geographic region, it is reasonable to conclude that there has been an increase in concussion reporting in our population.
Athletic trainers and coaches were the people to whom concussions were most frequently reported to in both the prior and current surveys. Interestingly, athletes from 2013 were significantly more likely to report to a coach than 1999 to 2002. This could be an effect of the many state laws that require coach education. If this is the case, athletes may be more willing to report to coaches if they perceive that having a concussion will not be frowned on by coaches as much as they were in the past.
Reasons for not reporting remained relatively unchanged, with a majority of those who did not report stating they did not think their injuries were serious enough. Reasons for not reporting were also similar across other studies using the same or similar questions to assess reasoning.11,22,23 However, high school football players in 2013 were more likely to state that they did not want to be pulled from a game or practice versus those in 1999 to 2002. This is consistent with the increased regulation of athletic programs that require athletes to be pulled from play if there is a suspected concussion. Before the law, athletes could return to play the same day as their injury. In accordance with WIAA policy,37 athletes must now follow a graded program of exertion (multiple days) before return to play.
For all high school athletes surveyed, only 59.5% were aware that Wisconsin has a state law regarding sport-related concussions, although all athletes are required to sign the informational sheet regarding the law. Subjects who sustained a concussion during the surveyed season most frequently stated that the law made no difference in whether or not they reported (68.0%). Those without a concussion most frequently stated that the law would make it more likely for them to report if they sustained a concussion (64.2%). This suggests that in theory, athletes believe the law would have a positive effect on their behavior of reporting, but in reality, the law does not seem to influence decision making in the majority of concussed athletes. A limiting factor in the effectiveness of the state legislation is athletes' awareness of the law, as 4 of 10 athletes reported being unaware of it. When looking at just those who reported awareness of the law, 55.1% stated it made it more likely that they reported a concussive injury. This does not account for the full increase in reporting rates but certainly sheds light on one of the factors that may have contributed to the rise in reporting. Interestingly, those who did not report concussions were more likely than previously to want to avoid being pulled from play, suggesting general knowledge of concussion management policies despite a lack of specific knowledge of the law.
As a retrospective survey study, we relied on athlete's recollection of concussive events; however, retrospective recall is known to be flawed and concussive injury known to cause memory problems (amnesia) in some individuals.38 Also, the description of concussion was derived from the original survey for consistency and was intended to help our athletes have a consistent and accurate knowledge base from which to answer questions. This definition was also used to assist student athletes in understanding the definition of concussion as opposed to more lengthy consensus-based definitions. Although published definitions of concussion have varied over the past decade, it is considered unlikely that our results are explained by the definition and description we used for this study. Although the questionnaire measure provided athletes with a common definition, we could not verify whether respondents read this information or instead answered the questions based on their own preconceived ideas about concussions. Finally, although our analyses of nonresponse patterns ruled out the potential for substantial nonresponse bias because of the host of demographic and other personal variables collected at preseason baseline testing, given the nonresponse rate in this survey, it is possible that such bias exists in ways that cannot be measured by our available participant data.
In summary, our results suggest that self-reported concussion rates have not changed drastically in the past 11 to 14 years, but the rate at which concussions are reported has increased significantly. Although this trend is heading in the right direction, a considerable number of athletes still do not report potential concussions and therefore are not getting recommended evaluation and treatment. In light of the finding that nearly half of athletes in our sample were unaware of the state law about concussion management, more focus is needed on engaging athletes in education efforts. Although new state laws may encourage injured athletes' removal from play, for most athletes, the laws do not seem to hinder reporting decisions. It should be noted that for a minority of athletes, the knowledge of the law and its implication for being removed from play may be an important determinant of whether concussions are reported. Although the Wisconsin law seems to have some positive role on reporting, there are probably numerous other reasons for reporting concussions that will be interesting to identify in future research. Social media (Facebook, Twitter), mass media (ESPN, news stories on pro-athletes, etc.), parental influence, coach rapport, and sport ethos all play a likely role.
1. Kerr ZY, Marshall SW, Harding HP Jr, et al.. Nine-year risk of depression diagnosis increases with increasing self-reported concussions in retired professional football players. Am J Sport Med. 2012;40:2206–2212.
2. Tator CH. Chronic traumatic encephalopathy: how serious a sports problem is it? Br J Sports Med. 2014;48:81–83.
3. McCrea M, Guskiewicz KM, Marshall SW, et al.. Acute effects and recovery time following concussion in collegiate football players: the NCAA Concussion Study. JAMA. 2003;290:2556–2563.
4. Nelson LD, Janecek JK, McCrea MA. Acute clinical recovery from sport-related concussion. Neuropsychol Rev. 2013;23:285–299.
5. Macciocchi SN, Barth JT, Alves W, et al.. Neuropsychological functioning and recovery after mild head injury
in collegiate athletes. Neurosurgery. 1996;39:510–514.
6. Giza CC, Hovda DA. The neurometabolic cascade of concussion. J Athl Train. 2001;36:228–235.
7. Armstrong C. Evaluation and management of concussion in athletes: recommendations from the AAN. Am Fam Physician. 2014;89:585–587.
8. McCrory P, Meeuwisse WH, Aubry M, et al.. Consensus statement on concussion in sport: the 4th International Conference on Concussion in Sport held in Zurich, 2012. Clin J Sport Med. 2013;23:89–117.
9. Daneshvar DH, Nowinski CJ, McKee AC, et al.. The epidemiology of sport-related concussion. Clin Sports Med. 2011;30:1–17.
10. McCrea M, Hammeke T, Olsen G, et al.. Unreported concussion in high school football players: implications for prevention. Clin J Sport Med. 2004;14:13–17.
11. Llewellyn T, Burdette GT, Joyner AB, et al.. Concussion reporting
rates at the conclusion of an intercollegiate athletic career. Clin J Sport Med. 2014;24:76–79.
12. Clay MB, Glover KL, Lowe DT. Epidemiology of concussion in sport: a literature review. J Chiropr Med. 2013;12:230–251.
13. Hootman JM, Dick R, Agel J. Epidemiology of collegiate injuries for 15 sports: summary and recommendations for injury prevention initiatives. J Athl Train. 2007;42:311–319.
14. Marar M, McIlvain NM, Fields SK, et al.. Epidemiology of concussions among United States high school athletes in 20 sports. Am J Sport Med. 2012;40:747–755.
15. Rivara FP, Schiff MA, Chrisman SP, et al.. The effect of coach education on reporting
of concussions among high school athletes after passage of a concussion law. Am J Sport Med. 2014;42:1197–1203.
16. Echlin PS, Tator CH, Cusimano MD, et al.. A prospective study of physician-observed concussions during junior ice hockey: implications for incidence rates. Neurosurg Focus. 2010;29:1–10.
17. Gessel LM, Fields SK, Collins CL, et al.. Concussions among United States high school and collegiate athletes. J Athl Train. 2007;42:495–503.
18. Guerriero RM, Proctor MR, Mannix R, et al.. Epidemiology, trends, assessment and management of sport-related concussion in United States high schools. Curr Opin Pediatr. 2012;24:696–701.
19. Kaut KP, DePompei R, Kerr J, et al.. Reports of head injury
and symptom knowledge among college athletes: implications for assessment and educational intervention. Clin J Sport Med. 2003;13:213–221.
20. Kroshus E, Daneshvar DH, Baugh CM, et al.. NCAA concussion education in ice hockey: an ineffective mandate. Br J Sports Med. 2014;48:135–140.
21. Meehan WP III, Mannix RC, O'Brien MJ, et al.. The prevalence of undiagnosed concussions in athletes. Clin J Sport Med. 2013;23:339–342.
22. Miyashita TL, Timpson WM, Frye MA, et al.. The impact of an educational intervention on college athletes' knowledge of concussions. Clin J Sport Med. 2013;23:349–353.
23. Register-Mihalik JK, Guskiewicz KM, McLeod TC, et al.. Knowledge, attitude, and concussion-reporting
behaviors among high school athletes: a preliminary study. J Athl Train. 2013;48:645–653.
24. Torres DM, Galetta KM, Phillips HW, et al.. Sports-related concussion: Anonymous survey of a collegiate cohort. Neurology. 2013;3:279–287.
25. Guskiewicz KM, Weaver NL, Padua DA, et al.. Epidemiology of concussion in collegiate and high school football players. Am J Sport Med. 2000;28:643–650.
26. Lincoln AE, Caswell SV, Almquist JL, et al.. Trends in concussion incidence in high school sports: a prospective 11-year study. Am J Sport Med. 2011;39:958–963.
27. Bakhos LL, Lockhart GR, Myers R, et al.. Emergency department visits for concussion in young child athletes. Pediatrics. 2010;126:550–556.
28. Metzl JD. Concussion in the young athlete. Pediatrics. 2006;117:1813.
29. McCrory P, Meeuwisse W, Johnston K, et al.. Consensus statement on concussion in sport: the 3rd International Conference on Concussion in Sport held in Zurich, November 2008. Clin J Sport Med. 2009;19:185–200.
30. Frollo J. USA Football. See where your state stands on concussion law. 2014. Accessed July 1, 2014. http://usafootball.com
32. Bagley AF, Daneshvar DH, Schanker BD, et al.. Effectiveness of the SLICE program for youth concussion education. Clin J Sport Med. 2012;22:385–389.
33. Shenouda C, Hendrickson P, Davenport K, et al.. The effects of concussion legislation
one year later–what have we learned: a descriptive pilot survey of youth soccer player associates. PM R. 2012;4:427–435.
34. LaRoche A. End of Season Survey. Palo Alto, CA: SurveyMonkey Inc; 2014.
35. Harris P, Taylor R, Thielke R, et al.. Research Electronic Data Capture (REDCap)- A metadata-driven methodology and workflow process for providing translational research informatics support. J Biomed Inform. 2009;42:377–381.
36. Converse PD, Wolfe EW, Huang XH, et al.. Response rates for mixed-mode surveys using mail and e-mail/web. Am J Eval. 2008;29:99–107.
38. McCrea M, Kelly JP, Randolph C, et al.. Immediate neurocognitive effects of concussion. Neurosurgery. 2002;50:1032–1040.
Keywords:Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
sport concussion; head injury; mild traumatic brain injury; legislation; reporting