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Incidence and Risk of Concussions in Youth Athletes: Comparisons of Age, Sex, Concussion History, Sport, and Football Position

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  • Straub Medical Center

Abstract and Figures

Objective: This study was designed to determine concussion incidence, risk, and relative risk among middle and high school athletes participating in various sports. Method: Data were retrospectively obtained from 10,334 athletes of 12 different sports in Hawaii. In addition to determining the overall concussion incidence, comparisons of incidence, risk, and relative risk were made according to age, sex, concussion history, sport, and football position. Results: The overall incidence of concussion among youth athletes was 1,250 (12.1%). The relative risk for a concussion was almost two times greater in 18-year olds than in 13-year-old athletes. In comparable sports, girls had a 1.5 times higher concussion risk than boys. Athletes with a prior concussion had 3-5 times greater risk to sustain a concussion than those with no history of a concussion. Among varied sports, wrestling and martial arts had the highest relative risk of a concussion, followed by cheerleading, football, and track and field. No differences in concussion risks were found among the football players in different positions. Conclusions: Older youths, females, those with a history of concussion, and those participating in high contact sports were found to have higher risks of sustaining a concussion. The findings increase awareness of concussion patterns in young athletes and raise concerns regarding protective strategies and concussion management in youth sports.
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Archives of Clinical Neuropsychology 34 (2019) 6069
Incidence and Risk of Concussions in Youth Athletes: Comparisons of
Age, Sex, Concussion History, Sport, and Football Position
William T. Tsushima
1,
*, Andrea M. Siu
2
, Hyeong Jun Ahn
3
, Bolin L. Chang
4
, Nathan M. Murata
5
1
Psychiatry and Psychology Department, Straub Medical Center, Honolulu, Hawaii 96813, USA
2
Research Institute, Hawaii Pacic Health, Honolulu, Hawaii 96813, USA
3
Department of Complementary and Integrative Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii 96813, USA
4
Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA
5
Department of Kinesiology and Rehabilitation Science, University of Hawaii, Honolulu, Hawaii 96822, USA
*Corresponding author at: Straub Medical Center, 888 South King Street, Honolulu, Hawaii 96813, USA. Tel.: +(808)-522-4521; fax: +(808)-522-3526.
E-mail address: tzking@gsu.edu (W.T. Tsushima).
Editorial Decision 22 January 2018; Accepted 16 February 2018
Abstract
Objective: This study was designed to determine concussion incidence, risk, and relative risk among middle and high school athletes par-
ticipating in various sports.
Method: Data were retrospectively obtained from 10,334 athletes of 12 different sports in Hawaii. In addition to determining the overall
concussion incidence, comparisons of incidence, risk, and relative risk were made according to age, sex, concussion history, sport, and foot-
ball position.
Results: The overall incidence of concussion among youth athletes was 1,250 (12.1%). The relative risk for a concussion was almost two
times greater in 18-year olds than in 13-year-old athletes. In comparable sports, girls had a 1.5 times higher concussion risk than boys.
Athletes with a prior concussion had 35 times greater risk to sustain a concussion than those with no history of a concussion. Among var-
ied sports, wrestling and martial arts had the highest relative risk of a concussion, followed by cheerleading, football, and track and eld.
No differences in concussion risks were found among the football players in different positions.
Conclusions: Older youths, females, those with a history of concussion, and those participating in high contact sports were found to have
higher risks of sustaining a concussion. The ndings increase awareness of concussion patterns in young athletes and raise concerns regard-
ing protective strategies and concussion management in youth sports.
Keywords: Concussion; Risks; Sports; Youth
Introduction
In the past decade, sports-related concussions have drawn considerable attention from the public, the media, state legisla-
tures, and sports medicine. Epidemiological reports provide convincing evidence that numerous concussions occur at all levels
of sport activity (Bakhos, Lockhart, Myers, & Linakis, 2010;Covassin & Elbin, 2011;OConnor et al., 2017;Stewart,
Gilliland, & Fraser, 2014). Public concern grows as concussion rates (CRs), typically dened as the number of concussions
divided by the number of athlete exposures (AEs) or participation in a practice or competition, have risen in recent years
(Comstock, Curie, & Pierpont, 2017;Lincoln et al., 2011;Zuckerman et al., 2015). The increasing trend may be due to
greater participation in sports and recreation, more concussion education, improved recognition of concussive events, and
new concussion management policies, but also to more concussions due to bigger, stronger, and faster athletes with greater
magnitude of head collisions (Daneshvar, Nowinski, McKee, & Cantu, 2011;Houck et al., 2016). Factors such as age, sex,
concussion history, sport played, and football position appear to be related to the occurrence of sport concussions.
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Age
Several recent epidemiologic reports of concussions among youth athletes have been published (Lincoln et al., 2011;
Meehan, dHemecourt, & Comstock, 2010;OConnor et al., 2017;Rosenthal, Foraker, Collins, & Comstock, 2014), with
data pertaining to age and varying in content and consistency. Some researchers have found CRs to be higher among high
school athletes than college athletes (Dompier, Kerr, & Marshall, 2015;Shankar, Fields, Collins, Dick, & Comstock, 2007;
Webbe & Barth, 2003), while others indicated higher CRs in college athletes compared to high school athletes (Gessel,
Fields, Collins, Dick, & Comstock, 2007;OConnor et al., 2017). Reports have variably placed the highest rates of sport-
related traumatic brain injury in the 1014 year-old age group (Centers for Disease Control and Prevention, 2007;Stewart
et al., 2014), in the 1214-year-old range (Kontos et al., 2016), in the 1419 years age range (Bakhos et al., 2010), and in the
15 to 24-year-old range (Thurman, Branche, & Sniezek, 1998). In sum, studies of youth sports concussion reveal varied and
conicting ndings regarding age, probably due to the differences in research methodology.
Sex
In sports medicine literature, CRs have been found generally to be higher in male athletes (Langlois, Rutland-Brown, &
Wald, 2006;Thurman et al., 1998), but in comparable sports females were consistently reported to have a similar or higher
CRs than males (Marar, McIlvain, Fields, & Comstock, 2012;Noble & Hesdorffer, 2013;OConnor et al., 2017;Rosenthal
et al., 2014). Overall, past studies suggest that CRs are higher in female athletes than males participating in comparable
sports.
Concussion History
Previous investigations have consistently found that individuals with a prior concussion have a greater risk to encounter
another concussion than those who have had no prior concussion. In a longitudinal study of 11,867 head injured children, in-
vestigators found that having a head injury increases the risk of having a subsequent head injury (Swaine et al., 2007).
Similarly, high school athletes with a history of a concussion are more prone to sustain a subsequent concussion than those
who have had no previous concussion (Collins et al., 2002;Schulz et al., 2004). Researchers have found that high school
players who sustain a concussion are 36 times more likely to sustain another concussion than those who had not had any
concussion (Guskiewicz, Weaver, Padua, & Garrett, 2000;Zemper, 2003), and that among concussed high school athletes,
10.5% were recurrent (Meehan et al., 2010). A recent epidemiologic study of concussion in seven high school and collegiate
sports found that athletes with a history of one concussion in the previous 24 months had over twice the rate of concussion
compared to those with no prior concussion, and those with two or more previous concussions had a ve times higher rate
(Marshall, Guskiewicz, Shankar, McCrea, & Cantu, 2015).
Sport Activities
Studies have found varying CRs across different high school sports. In many reports, the high school sport with the highest
CR is football (e.g., Marar et al., 2012;Noble & Hesdorffer, 2013;OConnor et al., 2017;Rosenthal et al., 2014), with lower
CRs observed in non-contact sports, such as volleyball, baseball, and swimming. However, a MEDLINE search from
19852000 stated that among high school male team sports, ice hockey athletes had the highest CR (3.6 per 1,000 AEs),
while soccer athletes had the lowest CR (0.18 per 1,000 AEs) (Tommasone & Valovich McLeod, 2006). In another report,
CRs were found to be highest in ice hockey and football in 1217-year olds (Bakhos et al., 2010). Finally, the High School
Reporting Information Online Injury Surveillance System (Comstock, Currie & Pierpoint, 2017) that collects data on 9 sports
from 100 randomly chosen study schools reported that, in the 20152016 school year, CRs were highest in girls soccer
(40.5%), girls basketball (31.7%), wrestling (28.3%), and football (27.5%). Overall, the sports medicine literature indicates
that CRs differ among high school sports, reecting the varying degrees of head impacts inherent in each sport (Harmon
et al., 2013;Koh, Cassidy, & Watkinson, 2003).
Football Positions
Researchers have noted that the position on a team, particularly in football, seems to affect the risk of concussion. Within
high school football, more concussions are found with linebackers and running backs than those in other positions (Gessel
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et al., 2007;Marar et al., 2012), possibly due to their sustaining more frequent collision impacts (Broglio et al., 2011). A
3-year study of 23,566 high school sports-related concussions revealed that the largest proportion of mild traumatic brain inju-
ries occurred among linebackers, running backs, and offensive linemen (Powell & Barber-Foss, 1999). The few available data
on high school football players suggest that more concussions are sustained by linebackers and running backs compared to
other football positions.
A report on sports-related concussion by the Institute of Medicine underlined the need for more comprehensive incidence
data in young athletes (Graham, Rivara, Ford, & Spicer, 2014). To date, there is limited research on the incidence of sports
concussions that occurs across the wide range of youth sports, particularly non-contact sports, like tennis or cross country.
The aim of this study was, rst, to determine concussion incidence, risk, and relative risk (RR) among middle and high school
athletes covering a broad spectrum of sports. Epidemiologic reports of sport concussions typically cover the popular sports of
football, basketball, soccer, baseball/softball, volleyball, and wrestling. In addition to these sports, this research examined
other sport activities that are not usually evaluated, that is, cross country, cheerleading, track and eld, water polo, and tennis.
Secondly, this research assessed differences in concussion incidences, risks, and RRs across the various sports according to
age, sex, concussion history, sport, and football position.
Method
The 10,334 participants in this research were athletes from schools who represented 67 public and private middle and high
schools in the State of Hawaii. Data for this study were obtained from the Immediate Post-Concussion Assessment and
Cognitive Testing (ImPACT) that athletes underwent prior to their respective sport seasons in the 20132014 school year.
ImPACT was administered in groups of 20 or fewer athletes, supervised by certied athletic trainers who were trained to
administer this computerized neuropsychological battery in a standardized manner. Biopsychosocial data yielded by ImPACT
included age, sex, sport played, football position, prior concussion and date of head injury. Approval for the use of the
research data was granted by the State of Hawaii Department of Education. The study was reviewed by the Hawaii Pacic
Health Research Institute and was determined to be exempt from Institutional Review Board review.
Participants
The subjects for this study were 5,938 males and 4,396 females, grades 812. The mean age was 15.5 years (SD =1.3).
Participants included 250 male and 262 female 13-year-olds, 1,295 male and 1,057 female 14-year-olds, 1,414 male and
1,063 female 15-year-olds, 1,456 male and 1,014 female 16-year-olds, 1,148 male and 796 female 17-year-olds, and 375
male and 204 female 18-year-olds.
The number of athletes in the varied sports was football (n=2,724), soccer (n=1,681), volleyball (n=1,202), basketball
(n=1,329), wrestling/martial arts (n=980), baseball (n=532), softball (n=441), cheerleading (n=533), water polo (n=
275), tennis (n=140), track and eld (n=137), and cross country (n=126). There were 234 who did not specify the sport
in which they participated.
From a pool of 10,334 participants in this research, 1,250 (12.1%) athletes sustained a concussion during their season.
Concussions were typically observed by the team staff and directly evaluated by the athletic trainer. A minority of athletes
experienced concussive symptoms after a game or practice, and reported their conditions that were assessed by the athletic
trainer. All of the concussed athletes underwent post-injury ImPACT testing. Certied athletic trainers at all of the schools
were available to verify the concussive events, adhering to the criteria provided by the consensus statement on concussion
(McCrory et al., 2013). Athletic trainers, having been certied to identify a concussion, received annual continuing education
through the Hawaii Concussion Awareness and Management Program, a state-funded community program that provides the
Hawaiis high school sports medical staffs with updated education to recognize and manage school-related sport concussions.
Of the total sample, 8,580 reported having no previous concussion, 1,299 had one previous concussion, 300 had two previous
concussions, and 111 had three or more previous concussions. There were 44 athletes with missing data regarding history of
concussions.
Statistical Analyses
This study calculated concussion incidence, risk, and RRs for age groups, sex, concussion history, sport, and football posi-
tion, with data provided by the Hawaii ImPACT database. Incidence refers to an injury occurring in a practice or competition
requiring attention from an athletic trainer or team physician. In this study, incidence proportion, or risk, reported in
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percentage, was calculated by dividing the number of athletes who incur a concussion during the season by the number of ath-
letes who participated in the sport. Risk is a valid estimate of the probability of injury and is readily understood, but it is less
often used in sports medicine literature because of its difculty in comparing injury risk in different sports (Knowles,
Marshall, & Guskiewicz, 2006). RR of a concussion was calculated by dividing the concussion risk of a group (e.g., 18 year-
olds) by the risk of a reference or comparison group (e.g., 13-year olds). In addition, adjusted RR (ARR) was calculated via
regression analyses to control for relevant factors, such as age, sex and sport. Ninety ve percent condence intervals (CI)
were generated for RRs and ARRs. Statistical signicance was set at p<0.05.
Results
In the varied sports studied over the school year, 1,250 (12.1%) athletes incurred a concussion. Concussion risks were
highest in the 18-year-old range (18.1%) and lowest in the 13-year-old (7.8%) and 14-year-old (7.6%) ranges. The ARR for
concussion, adjusted for sex and sport, for the 18-year olds was found to be nearly two times greater than for 13- and 14-year
olds (ARR =1.91, p=0.0003). Risk, RR, and ARR results, with 13-year olds as the reference group, are shown in Table 1.
In sports played by both sexes, girls had signicantly higher concussion risks than boys in three comparable sports: basket-
ball (14.8%), soccer (13.3%), and softball (12.8). The ARR for girls in all sports, including comparable sports, was 1½ times
greater than boys (ARR =1.50, p<0.0001). The risks, RRs, and ARRs, adjusted for age and sport (with boys as the refer-
ence group), are shown in Table 2.
Of the 8,580 who reported no prior concussions, 611 (7.1%) had a concussion during the 20132014 school year. Of the
1,299 who reported one prior concussion, 436 (33.6%) had a concussion during the school year. Of the 300 who reported two
prior concussions, 127 (42.3%) received a concussion. Of the 111 who reported three or more prior concussions, 33 (29.7%)
sustained a concussion during the school year. The ARR, adjusted for sex and sport, of those with two self-reported prior con-
cussions was 5.07 times greater than those with no self-reported prior concussion, while athletes with one self-reported prior
concussion had an ARR which was 4.34 times greater than those with no self-reported prior concussion, and those with three
or more self-reported prior concussions had an ARR which was 3.72 times greater than those with no self-reported previous
concussion. The risks, RRs, and ARRs for the self-reported concussion groups, with the no concussion group as the reference,
are presented in Table 3.
From among the various sports, the highest concussion risks were from participation in wrestling/martial arts (20.8%), fol-
lowed by cheerleading (15.9%), and football (15.4%). The lowest risks were in cross country (3.2%), tennis (3.6%), and water
polo (4.0%). Table 4shows the risks, RRs, and ARRs by sports, adjusted for age and sex, with cross country as the reference
group. Wrestling and martial arts obtained ARRs that were 6.07 times greater than cross country, followed by football (5.68)
and track and eld (4.24). Lowest ARR ratios were in water polo (1.00), tennis (1.10), and volleyball (1.35).
Among football players, the highest concussion risks were seen in running backs (18.9%), followed by defensive backs
(16.7%), and kickers (15.8%). Lowest risks were found to be with linebackers (13.4%) and defensive linemen (13.9%). With
linebackers as the reference group, running backs had an ARR, adjusted for age, that was 1.43 times greater than linebackers,
followed by defensive backs (1.26) and offensive linemen (1.16). The lowest ARR was seen in kickers (1.06). The risks,
RRs, and ARRs of the football positions are shown in Table 5.
Discussion
This large-scale research involving 10,334 middle and high school athletes offered a unique opportunity to examine the
incidence of concussions occurring during a single season of a wide variety of high school sports. While there are different
Table 1. Risk, RR, and adjusted RR by age
Age Number of athletes Number of concussions Risk (%) RR Adjusted RR
a
(95% CI) ARR p-value
13 512 40 7.8 Reference Reference NA
14 2,352 178 7.6 0.97 (0.70, 1.35) 0.82 (0.59, 1.15) 0.248
15 2,477 363 14.7 1.88 (1.37, 2.56) 1.53 (1.11, 2.11) 0.009**
16 2,470 309 12.5 1.60 (1.17, 2.19) 1.32 (0.96, 1.83) 0.089*
17 1,944 255 13.1 1.68 (1.22, 2.31) 1.39 (1.01, 1.93) 0.046*
18 579 105 18.1 2.32 (1.65, 3.28) 1.91 (1.35, 2.71) 0.0003**
a
Adjusted for sex and sport.
*p<0.05. **p<0.01.
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ways to report concussion data, we chose to examine concussion incidence in terms of risk, or the percent of athletes on a
team who sustained a concussion during the season. Risk indicates the probability of a concussion per athlete and is a valid
estimator of the chance of a concussion. Risk is less often employed in sports medicine research that typically reports CRs
based on athletic exposure, that is, number of games and practices, and is less applicable when comparing concussion in dif-
ferent sports that have varying amounts of games and practices (Knowles et al., 2006). The advantage of the risk data is that
they are more useful for risk assessment and may be more readily interpretable than CRs that require understanding the con-
cept of the person-time in AEs. The present investigation reported risks, RRs, and ARRs of concussion among varied sports
according to age, sex, concussion history, sport, and football position, expanding the understanding of youth sports
concussion.
Table 2. Risk, RR, and adjusted RR by sex and sport
Number of
athletes
Number of
concussions
Risk
(%)
RR Adjusted RR
a
(95% CI)
ARR
p-value
All sports
Male 5,938 719 12.1 Reference Reference
Female 4,396 531 12.1 1.00 (0.90, 1.11) 1.50 (1.29, 1.73) <.0001**
All comparable sports
Male 2,974 292 9.8 Reference Reference
Female 3,603 434 12.1 1.23 (1.07, 1.41) 1.50 (1.29, 1.74) <.0001**
Comparable Sports
Soccer
Male 711 55 7.7 Reference Reference
Female 970 129 13.3 1.72 (1.27, 2.32) 1.75 (1.30, 2.38) 0.0003**
Basketball
Male 701 64 9.1 Reference Reference
Female 628 93 14.8 1.62 (1.20, 2.19) 1.62 (1.20, 2.19) 0.0018**
Volleyball
Male 226 6 2.7 Reference Reference
Female 976 54 5.5 2.08 (0.91, 4.78) 2.21 (0.96, 5.09) 0.0626
Wrestling/martial arts
Male 636 123 19.3 Reference Reference
Female 344 81 23.5 1.22 (0.95, 1.56) 1.19 (0.93, 1.53) 0.1691
Baseball/ Softball
Male 525 34 6.5 Reference Reference
Female 438 56 12.8 1.97 (1.31, 2.97) 2.07 (1.38, 3.11) 0.0004**
Water polo
Male 102 2 2 Reference Reference
Female 173 9 5.2 2.65 (0.58, 12.04) 2.04 (0.44, 9.41) 0.3611
Tennis
Male 56 2 3.6 Reference Reference
Female 84 3 3.6 1.00 (0.17, 5.79) 1.04 (0.18, 6.00) 0.9676
Track & eld
Male 70 8 11.4 Reference Reference
Female 67 12 17.9 1.57 (0.68, 3.59) 1.66 (0.73, 3.80) 0.2269
Cross country
Male 71 3 4.2 Reference Reference
Female 55 1 1.8 0.43 (0.05, 4.02) 0.45 (0.05, 4.17) 0.4792
a
Adjusted for age.
**p<0.01.
Table 3. Risk, RR, and adjusted RR by concussion
Concussion group Number of athletes Number of concussions Risk (%) RR Adjusted RR
a
(95% CI) ARR p-value
0 8,580 611 7.1 Reference Reference NA
1 1,299 436 33.6 4.71 (4.23, 5.25) 4.34 (3.89, 4.83) <0.0001**
2 300 127 42.3 5.95 (5.10, 6.92) 5.07 (4.37, 5.88) <0.0001**
3+111 33 29.7 4.18 (3.11, 5.61) 3.72 (2.79, 4.97) <0.0001**
a
Adjusted for sex and sport.
**p<0.01.
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This research found that, from among the 10,334 athletes, 1,250 (or 12.1%) sustained a concussion during the school year.
This nding is lower than the 16.7% incidence proportion noted in a prospective 11-year study of concussion incidence in
high school sports by Lincoln et al. (2011). Differences in research methodology may account for the contrasting results. The
Lincoln epidemiological research employed an electronic medical record-keeping program on a daily basis as contrasted with
the retrospective data collection in this investigation. The different sports evaluated in the two studies could have also inu-
enced the variable results. In this study, concussions were found to occur more frequently with older high school athletes,
female athletes, players with a prior history of concussion, and athletes who participate in wrestling and martial arts.
Age
The ndings of this study indicated that older student athletes, that is, 18-year olds, have a much higher incidence of concus-
sions compared with younger student athletes, that is, 13-year olds. RR and ARR data showed that 18-year-old athletes have
about twice the risk of sustaining a concussion compared to 13-year olds. These results are noteworthy in that, to our knowledge,
no study has examined concussion risks in specic ages of youth athletes. Older youth athletes may suffer more concussions as
they may have more playing time, are bigger and stronger, and play at a faster, more intense and competitive level that could
increase the risk of severe impacts and concussion (Gessel et al., 2007). Some older athletes may have sustained a concussion
earlier in their school years, thus increasing their risk of concussions in subsequent head injuries (Zemper, 2003).
This research highlights the need for additional studies into the age factor in youth sports concussions, especially for the older stu-
dent athlete. Concussion data pertaining to middle school and grade school athletes are rare, calling for more research in these younger
age groups, who receive less professional medical attention than college and professional athletes (Halstead & Walter, 2010).
Sex
The present study found higher concussion risks in female youth athletes when compared to males over a wide range of
comparable sport activities. In certain sports, such as basketball, soccer, and softball, female athletes had over 1.52 times the
Table 5. Risk, RR, and adjusted RR by football position
Position Number of athletes Number of concussions Risk (%) RR Adjusted RR
a
(95% CI) ARR p-value
Running back 196 37 18.9 1.41 (0.94, 2.12) 1.43 (0.95, 2.14) 0.09
Defensive back 365 61 16.7 1.25 (0.87, 1.80) 1.26 (0.87, 1.81) 0.22
Kicker 19 3 15.8 1.18 (0.40, 3.46) 1.06 (0.36, 3.12) 0.92
Offensive lineman 279 43 15.4 1.15 (0.77, 1.71) 1.16 (0.78, 1.73) 0.46
Quarterback 113 16 14.2 1.06 (0.62, 1.81) 1.07 (0.63, 1.83) 0.79
Receiver 487 69 14.2 1.06 (0.74, 1.51) 1.08 (0.75, 1.55) 0.67
Defensive lineman 366 51 13.9 1.04 (0.71, 1.52) 1.04 (0.71, 1.52) 0.84
Linebacker 306 41 13.4 Reference Reference NA
a
Adjusted for age.
Table 4. Risk, RR, and adjusted RR by sport
Sport Number of athletes Number of concussions Risk (%) RR Adjusted RR
a
(95% CI) ARR p-value
Wrestling/martial arts 980 204 20.8 6.56 (2.48, 17.33) 6.07 (2.30, 16.02) 0.0003**
Cheerleading 533 85 15.9 5.02 (1.88, 13.44) 3.99 (1.49, 10.70) 0.0059**
Football 2,724 420 15.4 4.86 (1.84, 12.79) 5.68 (2.15, 14.98) 0.0005**
Track and eld 137 20 14.6 4.60 (1.62, 13.09) 4.24 (1.49, 12.04) 0.0067**
Softball 441 56 12.7 4.00 (1.48, 10.82) 3.28 (1.21, 8.89) 0.0193*
Basketball 1,329 157 11.8 3.72 (1.40, 9.87) 3.52 (1.33, 9.32) 0.0114*
Soccer 1,681 184 10.9 3.45 (1.30, 9.13) 3.11 (1.18, 8.23) 0.0223*
Baseball 532 34 6.4 2.01 (0.73, 5.57) 2.39 (0.86, 6.61) 0.0945
Volleyball 1,202 60 5 1.57 (0.58, 4.25) 1.35 (0.50, 3.67) 0.5518
Water polo 275 11 4 1.26 (0.41, 3.88) 1.00 (0.32, 3.12) 0.9998
Tennis 140 5 3.6 1.13 (0.31, 4.10) 1.10 (0.30, 3.99) 0.8868
Cross country 126 4 3.2 Reference Reference NA
a
Adjusted for age and sex
*p<0.05. **p<0.01.
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RR and ARR of a concussion than males. A literature review of sex difference in sport concussion in high school, college,
and professional levels likewise showed higher CRs for females compared to males in similar sports (Dick, 2009), a pattern
that has been noted in several previous studies of high school athletes (Lincoln et al., 2011;Marar et al., 2012;Rosenthal
et al., 2014). Possible explanations for sex differences in concussion patterns are limited, with some suggesting biomechanical
(body mass, small head-to-ball ratio, neck strength), neuroanatomical, or hormonal factors underlying female concussions
(Covassin, Swanik, & Sachs, 2003;Strand, Lechuga, Zachariah, & Beaulieu, 2015). Psychosocial inuences may lead males
to minimize injuries, play despite injury and underreport symptoms in order to continue to play (Kerr, Register-Mihalik,
Kroshus, Baugh, & Marshall, 2016). Along with prior ndings that female athletes exhibit more neuropsychological decline
than males following sports-related concussion (Broshek et al., 2005;Covassin, Elbin, Harris, Parker, & Kontos, 2012), the
present results call for further research regarding concussion risks and prevention strategies in female youth athletes.
Prior concussion
One of the signicant ndings in this report is that youth athletes who report having a prior concussion are three to ve
times more likely to sustain a concussion during the school year than athletes without a reported history of concussion. The
athletes with one self-reported prior concussion had an ARR that was over four times greater than those with no self-reported
prior concussions. The ARR for athletes with two self-reported prior concussions was ve times greater than those with no
self-reported previous concussion, and for those with three or more self-reported prior concussion was more than three times
greater than those who had no self-reported prior concussion. The data do not support a doseresponse relationship between
the number of self-reported concussions and subsequent concussive events.
A mild brain trauma results not only in immediate physiological changes but may affect neuronal plasticity and increase
the risk for a subsequent concussion (Giza & Hovda, 2001;Noble & Hesdorffer, 2013). Thus, the capacity of the brain of pre-
viously concussed athletes to respond to another head trauma may be compromised and is, therefore, more susceptible to a
subsequent concussion. It has also been proposed that high school athletes who had a prior concussion may be the more expe-
rienced players who participate more in games and practices and are more likely to have another concussion because of
greater exposure to play activity (Schulz et al., 2004). The present ndings are consistent with observations by previous inves-
tigators (Collins et al., 2002;Guskiewicz et al., 2000), and have important implications for the proper management of head
injured young athletes (Gavett, Stern, & McKee, 2011;Graham et al., 2014;Harmon et al., 2013).
Sports
More concussion incidents seem to occur in certain sports. The highest percentage of concussions and ARRs was seen in
wrestling and martial arts, followed by cheerleading and football. While many studies of high school sports have consistently
found football to have the highest CRs among the varied sport activities (Lincoln et al., 2011;Marar et al., 2012;Noble &
Hesdorffer, 2013;Rosenthal et al., 2014;Shankar et al., 2007), wrestling and cheerleading have also been noted to have high
concussion risks (Comstock et al., 2017;Stewart et al., 2014). In previous studies of CRs, participants in wrestling and cheer-
leading have not been identied among those with the highest CRs, most likely because of their lower exposure to sport activ-
ity, compared with football or ice hockey. Instead of risk data, most previous comparisons of sports have employed CRs that
take into account AE, or total person-time at risk, which is considered to be the most appropriate way to compare different
sports (Knowles et al., 2006), but was not available for this study.
Football positions
None of the ARRs comparing the different football positions, with linebackers as the reference, was statistically signicant.
The lack of differences between the varied football positions may be attributed to the youth athletes playing in more than one
position or playing on offense and defense.
Limitations
In this research, concussions that occurred during the school year were documented by a certied athletic trainer, but the
history of prior concussions was obtained by the self-report of the athlete. The actual number of self-reported concussions is
likely underestimated due to the failure of accurate documenting of head injuries by young athletes and support staff (Kerr
et al., 2016;Williamson & Goodman, 2006). Reasons for the underreporting of concussions include the athletes unawareness
66 W.T. Tsushima et al. / Archives of Clinical Neuropsychology 34 (2019); 6069
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of having sustained a concussion, minimizing the seriousness of the head blow, and deliberately not reporting a concussion so
as to avoid being withheld from participating.
The participants in this study were a convenience sample enrolled in schools in Hawaii, with results that could assist in
region-specic efforts to improve concussion education and increase player safety. However, our results may not be generaliz-
able to schools in other geographic locations and with different sociocultural representation. The gathering of similar risk inci-
dence data from other regions in the country could enhance the generalizability of these ndings. Although this research
examined 12 different sports in Hawaii, it did not include other sports that are associated with high risks of concussion in
other states and countries, such as hockey, lacrosse, and rugby.
The athletes in this study were identied as participating in one sport, but youth athletes often play in multiple sports. If an
identied football player sustained a concussion in baseball but not in football, he was counted as a baseball player who had a
concussion and also counted as football player who did not have a concussion. However, we do not know how many athletes
who did not suffer any concussion played in more than one sport. Limitations should be recognized regarding the retrospec-
tive nature of this study that lacked a systematic method for tracking athletes who sustained a concussion, with unknown in-
tervals between the occurrence of a concussion and its reporting. The present data did not include the circumstances of the
head injuries, for example, whether a concussion was due to head-to-head, head-to-body, or ground contact, and did not dif-
ferentiate a concussion sustained in practice or in a game. Finally, our ndings provide no clear understanding of factors,
such as age and sex, which may predispose an athlete to a concussion.
Conclusion
While the interest in sports-related concussion is often focused in major collision sports, like football, the present study,
through a large sample of high school athletes, provides information about the incidence and risk of concussion across a wide
spectrum of team and individual sports. Our ndings show that concussion risks vary considerably by age, sex, concussion
history, and sport. Reporting concussion incidence and risk rates have intrinsic informative value for athletes, parents, coa-
ches, and athletic staff. The present ndings increase our knowledge and understanding of concussion patterns in high school
athletes in various sports that can enhance protective and preventative strategies with these young participants.
Funding
HJA was partially supported by grant U54MD007584 from the National Institute on Minority Health and Health
Disparities. The content is solely the responsibility of the authors and does not necessarily represent the ofcial views of the
NIH.
Conict of interest
None declared.
Acknowledgements
The ImPACT data were provided by the Hawaii Concussion Awareness and Management Program (HCAMP). The authors
thank the Hawaii State Department of Education for their support, and the certied athletic trainers who submitted the data to
HCAMP. The fourth author, BLC, participated in the Hawaii Pacic Health Summer Student Research Program while he as-
sisted in this research project.
References
Bakhos, L. L., Lockhart, G. R., Myers, R., & Linakis, J. G. (2010). Emergency department visits for concussion in young child athletes. Pediatrics,126,
e550e556.
Broglio, S. P., Eckner, J. T., Martini, D., Sosnoff, J. J., Kutcher, J. S., & Randolph, C. (2011). Cumulative head impact burden in high school football.
Journal of Neurotrauma,28, 20692076.
Broshek, D. K., Kaushik, T., Freeman, J. R., Erlanger, D., Webbe, F., & Barth, J. T. (2005). Sex differences in outcome following sports-related concussion.
Journal of Neurosurgery,102, 856863.
Centers for Disease Control and Prevention. (2007). Nonfatal traumatic brain injuries from sports and recreation activitiesUnited States, 20012005.
MMWR Weekly,56, 733737.
67W.T. Tsushima et al. / Archives of Clinical Neuropsychology 34 (2019); 6069
Downloaded from https://academic.oup.com/acn/article-abstract/34/1/60/4938567 by NAN Member Access, William Tsushima on 26 February 2019
Collins, M. W., Lovell, M. R., Iverson, G. L., Cantu, R. C., Maroon, J. C., & Field, M. (2002). Cumulative effects of concussion in high school athletes.
Neurosurgery,51, 11751181.
Comstock, R. D., Currie, D. W., & Pierpoint, L. A. (2017). National High School Sports-Related Injury Surveillance Study: Summary Report, 20152016
School Year. Retrieved July 5, 2017 from http://www.nationwidechildrens.org/cirp-rio-publications.
Covassin, T., & Elbin, R. J. (2011). History and epidemiology of concussion in sport. In Webbe. F. M. (Ed.), The handbook of sport neuropsychology (pp.
5874). New York: Springer Publishing Company.
Covassin, T., Elbin, R. J., Harris, W., Parker, T., & Kontos, A. (2012). The role of age and sex in symptoms, neurocognitive performance, and postural stabil-
ity in athletes after concussion. American Journal of Sports Medicine,40, 13031312.
Covassin, T., Swanik, C. B., & Sachs, M. L. (2003). Sex differences and the incidence of concussions among collegiate athletes. Journal of Athletic Training,
38, 238244.
Daneshvar, D. H., Nowinski, C. J., McKee, A. C., & Cantu, R. C. (2011). The epidemiology of sport-related concussion. Clinics in Sports Medicine,30 (1),
117.
Dick, R. W. (2009). Is there a gender difference in concussion incidence and outcomes? British Journal of Sports Medicine,43, i46i50.
Dompier, T. P., Kerr, Z. Y., & Marshall, S. W. (2015). Incidence of concussion during practice and games in youth, high school, and collegiate American
football. JAMA Pediatrics,169, 659665.
Gavett, B. E., Stern, R. A., & McKee, A. C. (2011). Chronic traumatic encephalopathy: A potential late effect of sport-related concussive and subconcussive
head trauma. Clinics in Sports Medicine,30, 179188.
Gessel, L. M., Fields, S. K., Collins, C. L., Dick, R. W., & Comstock, R. D. (2007). Concussions among United States high school and collegiate athletes.
Journal of Athletic Training,42, 495503.
Giza, C. C., & Hovda, D. A. (2001). The neurometabolic cascade of concussion. Journal of Athletic Training,36, 228235.
Graham R., Rivara F. P., Ford M. A., & Spicer C. M. (Eds.) (2014). Sports-related concussion in youth: Improving the science, changing the culture.
Washington, D.C.: The National Academies Press.
Guskiewicz, K. M., Weaver, N. L., Padua, D. A., & Garrett, W. E., Jr. (2000). Epidemiology of concussion in collegiate and high school football players.
American Journal of Sports Medicine,28, 643650.
Halstead, M. E., & Walter, K. D. (2010). Clinical reportsport-related concussion in children and adolescents. Pediatrics,126, 597615.
Harmon, K. G., Drezner, J. A., Gammons, M., Guskiewicz, K. M., Halstead, M., Herring, S. A., et al. (2013). American Medical Society for Sports Medicine
position statement: Concussion in sport. British Journal of Sports Medicine,47,1526. doi:10.1136/bjsports-2012-091941.
Houck, Z., Asken, B., Bauer, R., Pothast, J., Michaudet, C., & Clugston, J. (2016). Epidemiology of sport-related concussion in an NCAA Division I
Football Bowl Subdivision sample. American Journal of Sports Medicine,44, 22692275.
Kerr, Z. Y., Register-Mihalik, J. K., Kroshus, E., Baugh, C. M., & Marshall, S. W. (2016). Motivations associated with non-disclosure of self-reported con-
cussions in former collegiate athletes. American Journal of Sports Medicine,44, 220225.
Knowles, S. B., Marshall, S. W., & Guskiewicz, K. M. (2006). Issues in estimating risks and rates in sports injury research. Journal of Athletic Training,41,
207215.
Koh, J. O., Cassidy, J. D., & Watkinson, E. J. (2003). Incidence of concussion in contact sports: A systematic review of the evidence. Brain Injury,17,
901917.
Kontos, A. P., Elbin, R. J., Sufrinko, A., Dakan, S., Bokwalter, K., Price, A., et al. (2016). Incidence of concussion in youth ice hockey players. Pediatrics,
137 (2), 16.
Langlois, J. A., Rutland-Brown, W., & Wald, M. M. (2006). The epidemiology and impact of traumatic brain injury: A brief overview. Journal of Head
Trauma Rehabilitation,21, 375378.
Lincoln, A. E., Caswell, S. V., Alonquist, J. L., Dunn, R. E., Norris, J. B., & Hinton, R. Y. (2011). Trends in concussion incidence in high school sports:A
prospective 11-year study. American Journal of Sports Medicine,39, 958963.
Marar, M., McIlvain, N. M., Fields, S. K., & Comstock, R. D. (2012). Epidemiology of concussions among United States high school athletes in 20 sports.
American Journal of Sports Medicine,40, 747755.
Marshall, S. W., Guskiewicz, K. M., Shankar, V., McCrea, M., & Cantu, R. C. (2015). Epidemiology of sports-related concussion in seven US high school
and collegiate sports. Injury Epidemiology,2, 13. DOI:10.1186/s40621-95-0045-4.
McCrory, P., Meeuwisse, W., Aubry, M., Cantu, B., Dvorak, J., Echemendia, R. J., et al. (2013). Consensus statement on concussion in sport. The 4th
International Conference on Concussion in Sport held in Zurich, November 2012. Journal of Athletic Training,48, 554575.
Meehan, W. P., III, dHemecourt, P., & Comstock, R. D. (2010). High school concussions in the 20082009 academic year. American Journal of Sports
Medicine,38, 24052409. doi:10. 1177/0363546510376737.
Noble, J. M., & Hesdorffer, D. C. (2013). Sport-related concussions: A review of epidemiology, challenges in diagnosis, and potential risk factors.
Neuropsychological Review,23, 273284. doi10.1007/s11065-013-9239-0.
OConnor, K. L., Baker, M. M., Dalton, D. S. L., Dompier, T. P., Broglio, S. P., & Kerr, Z. Y. (2017). Epidemiology of sport-related concussion in high
school athletes: National Athletic Treatment, Injury and Outcomes Network (NATION), 20112012 through 20132014. Journal of Athletic Training,52,
175185.
Powell, J. W., & Barber-Foss, K. D. (1999). Traumatic brain injury in high school athletes. JAMA,282, 958963.
Rosenthal, J. A., Foraker, R. E., Collins, C. L., & Comstock, R. D. (2014). National high school athletic concussion rates from 20052006 to 20112012.
American Journal of Sports Medicine,42, 17101715. doi:10.1177/0363546514530091.
Schulz, M. R., Marshall, S. W., Mueller, F. O., Yang, J., Weaver, N. L., Kalsbeek, W. D., et al. (2004). Incidence and risk factors for concussion in high
school athletes, North Carolina, 19961999. American Journal of Epidemiology,160, 937944.
Shankar, P. R., Fields, S. K., Collins, C. L., Dick, R. W., & Comstock, R. D. (2007). Epidemiology of high school and collegiate football injuries in the
United States, 20052006. American Journal of Sports Medicine,35, 12951303. doi:10.1177/036546507299745.
Stewart, T. C., Gilliland, J., & Fraser, D. D. (2014). An epidemiologic prole of pediatric concussions: Identifying urban and rural differences. Journal of
Trauma and Acute Care Surgery,76, 736742. doi:10.1097/TA.0b013c3182aafd5.
68 W.T. Tsushima et al. / Archives of Clinical Neuropsychology 34 (2019); 6069
Downloaded from https://academic.oup.com/acn/article-abstract/34/1/60/4938567 by NAN Member Access, William Tsushima on 26 February 2019
Strand, S., Lechuga, D., Zachariah, T., & Beaulieu, K. (2015). Relative risk for concussions in young female soccer players. Applied Neuropsychology:
Child,4,5864.
Swaine, B. R., Tremblay, C., Platt, R. W., Grimard, G., Zhang, X., & Pless, I. B. (2007). Previous head injury is a risk factor for subsequent head injury in
children: A longitudinal cohort study. Pediatrics,119, 749758.
Thurman, D. J., Branche, C. M., & Sniezek, J. E. (1998). The epidemiology of sports-related traumatic brain injury in the United States: Recent develop-
ments. Journal of Head Trauma Rehabilitation,13 (2), 18.
Tommasone, B. A., & Valovich McLeod, T. C. (2006). Contact sport incidence. Journal of Athletic Training,41, 470472.
Webbe, F. M., & Barth, J. T. (2003). Short-term and long-term outcome of athletic closed head injuries. Clinics in Sports Medicine,22, 577592.
Williamson, I. J. S., & Goodman, D. (2006). Converging evidence for the under-reporting of concussions in youth ice hockey. British Journal of Sports
Medicine,40, 128132.
Zemper, E. D. (2003). Two-year prospective study of relative risk of a second cerebral concussion. American Journal of Physical Medicine and
Rehabilitation,82, 653659.
Zuckerman, S. L., Kerr, Z. Y., Yengo-Kahn, A., Wasserman, E., Covassin, T., & Solomon, G. S. (2015). Epidemiology of sports-related concussion in
NCAA athletes from 20092010 to 20132014. American Journal of Sports Medicine,43, 26542662.
69W.T. Tsushima et al. / Archives of Clinical Neuropsychology 34 (2019); 6069
Downloaded from https://academic.oup.com/acn/article-abstract/34/1/60/4938567 by NAN Member Access, William Tsushima on 26 February 2019
... Consensus is lacking regarding head injury prevalence by sex in soccer 2 : Some analyses [6][7][8][9]12,15,22,25,28 have reported that female players had a higher concussion incidence rate than male players had, whereas other studies 11,28 have reported no significant differences between sexes. Research 8,9,12,15,22,25 looking at sex-based differences across other sports primarily has found that female players had a greater concussion incidence rate than male players had. ...
... Consensus is lacking regarding head injury prevalence by sex in soccer 2 : Some analyses [6][7][8][9]12,15,22,25,28 have reported that female players had a higher concussion incidence rate than male players had, whereas other studies 11,28 have reported no significant differences between sexes. Research 8,9,12,15,22,25 looking at sex-based differences across other sports primarily has found that female players had a greater concussion incidence rate than male players had. Soccer studies that evaluated age and head injury have reported that high school athletes took longer to recover after a concussion compared with collegiate athletes 9,19,24 yet collegiate athletes had a greater occurrence of concussions compared with high school athletes. ...
... Soccer studies that evaluated age and head injury have reported that high school athletes took longer to recover after a concussion compared with collegiate athletes 9,19,24 yet collegiate athletes had a greater occurrence of concussions compared with high school athletes. 12,17,25 The research evaluating soccer head injuries by position is more limited in terms of quantity of studies, and a variety of results have been reported regarding the highest concussion incidence: One study reported that defenders had the greatest risk, 2 another reported forwards, 26 and 2 other studies reported goalkeepers. 9,10 The purpose of this study was to conduct an in-depth analysis of soccer players across these 3 key demographic groups (sex, age, position) for both concussion incidence and severity. ...
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... re likely to experience issues with attention deficits, hyperactivity, or other issues that can inhibit a person's ability to effectively elicit the task of anticipation. These decrements, as a result to early exposure to TBIs at a younger age, can be associated with the damage that comes with prefrontal cortex impairments (Daneshvar et. al., 2011;Tsushima et. al., 2018). ...
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The present study sought to understand traumatic brain injuries (TBI) impact on executive function (EF) in terms of anticipation amongst individuals with a background in soccer; along with other contributing factors of EF curtailments that inhibit athletes. Within this study 57 participants, with a background in soccer (high school, collegiate, and semi-professional), completed five EF tasks: working memory, cognitive flexibility, attentional control, and anticipation; pattern detection and athletic cues (temporal occlusion). The results of this study concluded that when TBI history, gender, and soccer athletic level are factors, athletes with a soccer level of collegiate and semi-professional had decrements related to pattern detection anticipation; meaning athletes at higher levels had lower average scores on the Brixton Spatial Anticipation Test (BSAT). Additionally, female athletes showed more anticipation decrements related to athletic cues, especially those that are reliant on the initiation of judgment. Overall undiagnosed TBIs and limited understanding on how to approach rehabilitation to mitigate EF decrements, continue to impede individual autonomy amongst athletes.
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This study sought to identify factors that reduce parental concern of concussion risks for children who play youth tackle American football. Interviews were conducted with parents who allowed children between the ages of 10 and 15 years to play on tackle football teams. Factors that reduced parental concern included advances in equipment safety and helmet technology, active parental monitoring and relationship building with coaches, and social comparisons to other youth athletes regarding their own child’s athleticism and ability to avoid injury. Although these factors reduced parents’ concern for concussion risks, the findings highlight biases that influence parental risk judgments, suggest that interventions to reduce concussions must account for competing narratives of concussion prevention, and offer recommendations for improving education efforts focused on player safety in contact sports.
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Prior studies have reported an association between concussion and suicidality in high school students in the United States. However, when controlling for multiple life stressors in adolescence (e.g., bullying, substance use, poor grades), the relationship between concussion and suicidality was either attenuated or became nonsignificant in one study. Rather than assessing concussion as a possible risk factor for suicidality, this study examined predictors of ideation, planning, and attempts among youth who experienced concussion in the past year. The sample included 13,677 participants from the 2019 Youth Behavior Risk Survey, of whom 1,754 (13%) reported experiencing a concussion in the past year. Binary logistic regressions were conducted to predict ideation, planning, and attempts with modifiable stress factors, including physical activity, bullying, poor grades, insufficient sleep, binge drinking, marijuana use, illicit drug use, and depression. Among adolescents who experienced a concussion in the past year, 25% reported suicidal ideation (31% girls/19% boys), 20% reported suicide planning (25% girls/17% boys), and 15% reported a suicide attempt (17% girls/13% boys). In a multivariable model among girls with prior year concussion, being bullied (OR=2.37), illicit drug use (OR=2.80), current marijuana use (OR=2.47), and depression (OR=9.22) predicted suicidal ideation. Among boys with prior year concussion, being bullied (OR=2.29) and depression (OR=9.50) predicted suicidal ideation. Additional models were used to examine the association between having one or more modifiable stressors and suicidality, revealing that having three or more modifiable stressors was associated with a substantial increase in proportions of youth reporting suicidality. Among adolescents experiencing a concussion, treating depression and substance use, stopping bullying, and increasing physical activity may be associated with reduced risk for suicidality.
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Objective: Concussion incidence is known to be highest in children and adolescents; however, there is conflicting evidence about the effect of age on concussion risk and recovery within the adolescent age range. The heterogeneity of results may be partially due to the use of age groupings based on convenience, making comparisons across studies difficult. This study evaluated the independent effect of age on concussion incidence, severity, and recovery in student-athletes aged 12-18 years using cluster analysis to define groupings. Methods: Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) scores of 11,403 baseline tests and 4922 postinjury tests were used to calculate the incidence rates for adolescent student-athletes grouped into 3 age bands (12-13, 14-15, and 16-18 years of age) on the basis of clustering analysis. The recently created Severity Index was used to compare concussion severity between groups. Follow-up tests for subjects who sustained a concussion were used to evaluate recovery time. The chi-square test and 1-way ANOVA were used to compare differences in demographic characteristics and concussion incidence, severity, and recovery. Multivariable logistic and linear regressions were used to evaluate the independent effects of age on concussion incidence and severity, respectively. Multivariable Cox hazard regression was used to evaluate differences in recovery time. Further analyses were conducted to directly compare findings across studies on the basis of the age groupings used in prior studies. Results: Multivariable regression analyses demonstrated that the 14- to 15-year-old age group had a significantly higher concussion incidence than both the 12- to 13-year-old (14- to 15-year-old group vs 12- to 13-year-old group, OR 1.57, 95% CI 1.16-2.17, p = 0.005) and 16- to 18-year-old (16- to 18-year-old group vs 14- to 15-year-old group, OR 0.79, 95% CI 0.69-0.91, p = 0.0008) age groups. There was no difference in incidence between the 12- to 13-year-old and 16- to 18-year-old groups (16- to 18-year group vs 12- to 13-year group, OR 1.26, 95% CI 0.93-1.72, p = 0.15). There were also no differences in concussion severity or recovery between any groups. Conclusions: This study found that concussion incidence was higher during mid-adolescence than early and late adolescence, suggesting a U-shaped relationship between age and concussion risk over the course of adolescence. Age had no independent effect on concussion severity or recovery in the 12- to 13-, 14- to 15-, and 16- to 18-year-old groups. Further analysis of the various age groups revealed that results may vary significantly with minor changes to groupings, which may explain the divergent results in the current literature on this topic. Thus, caution should be taken when interpreting the results of this and all similar studies, especially when groupings are based on convenience.
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OBJECTIVE: This study assesses concussion rates and current headaches in female soccer versus non-contact sport athletes who have progressed to higher levels of competition in college. METHODS: Soccer and non-contact sport female athletes from four universities completed questionnaires on concussion history and current headaches. RESULTS: Soccer athletes had a significantly higher rate of concussions compared to non-contact athletes (50% versus 9%, p<0.0001), but there was not a significant difference in current headaches between the two groups (20% soccer; 32% non-contact). Among soccer athletes, 56% of goalkeepers, defenders, and forwards collectively reported a concussion, while only 23% of midfielders reported a concussion (p=0.03). Rates of reported headaches were significantly higher in soccer athletes with <15 years of experience (38% versus 11%, p=0.009). CONCLUSION: Collegiate female soccer athletes had a higher rate of concussions versus non-contact-sport athletes, but no difference in rate of current headaches existed. Soccer athletes with <15 years of experience reported higher rates of headaches.
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Context: Sports participation is one of the leading causes of concussions among nearly 8 million US high school student-athletes. Objective: To describe the epidemiology of sport-related concussion (SRC) in 27 high school sports during the 2011-2012 through 2013-2014 academic years. Design: Descriptive epidemiology study. Setting: Aggregate injury and exposure data from 27 sports in 147 high schools in the National Athletic Treatment, Injury and Outcomes Network (NATION). Patients or other participants: Boy and girl high school athletes during the 2011-2012 through 2013-2014 academic years. Main outcome measure(s): Sport-related concussion counts, percentages, rates per 10 000 athlete-exposures (AEs), rate ratios (RRs), and injury proportion ratios (IPRs) were reported with 95% confidence intervals (CIs). Rate ratios and IPRs with 95% CIs not containing 1.0 were considered significant. Results: Overall, 2004 SRCs were reported among 27 high school sports, for a rate of 3.89 per 10 000 AEs. Football had the highest SRC rate (9.21/10 000 AEs), followed by boys' lacrosse (6.65/10 000 AEs) and girls' soccer (6.11/10 000 AEs). The SRC rate was higher in competition than in practice (RR = 3.30; 95% CI = 3.02, 3.60). Among sex-comparable sports, the SRC rate was higher in girls than in boys (RR = 1.56; 95% CI = 1.34, 1.81); however, the proportion of SRCs due to player-to-player contact was higher in boys than in girls (IPR = 1.48; 95% CI = 1.27, 1.73). Common symptoms reported among all athletes with SRCs were headache (94.7%), dizziness (74.8%), and difficulty concentrating (61.0%). Only 0.8% of players with SRCs returned to play within 24 hours. The majority of athletes with SRCs (65.8%) returned to play between 7 and 28 days. More players had symptoms resolve after 7 days (48.8%) than less than a week (40.7%). Conclusions: Our findings provide updated high school SRC incidence estimates and further evidence of sex differences in reported SRCs. Few athletes with SRCs returned to play within 24 hours or a week. Most injured players returned after 7 days, despite a smaller proportion having symptoms resolve within a week.
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Background: Ice hockey is a fast-paced collision sport that entails both intentional (ie, body checking) and incidental contact that may involve the head. The objective of this study was to determine the incidence of concussions in relation to games/practices and age among competition-level youth ice hockey players (ages 12-18 years). Methods: Participants included 397 youth ice hockey players from Western Pennsylvania; Boston, Massachusetts; and Birmingham, Alabama, during the 2012-2013 and 2013-2014 youth ice hockey seasons. Incidence rates (IRs) and incidence rate ratios (IRRs) of concussion were calculated for games/practices and age groups. Results: A total of 23 369 (12 784 practice/10 585 game) athletic exposures (AEs) involving 37 medically diagnosed concussions occurred. More than 40% of concussions involved illegal contact. The combined IR for games and practices was 1.58 concussions per 1000 AEs. The IRR was 2.86 times (95% confidence interval 0.68-4.42) higher during games (2.49 per 1000 AEs) than practices (1.04 per 1000 AEs). Conclusions: The overall IR for concussion in youth ice hockey was comparable to those reported in other youth collision sports. The game-to-practice IRR was lower than previously reported in ice hockey and other youth sports, although more concussions per exposure occurred in games compared with practices. Younger players had a higher rate of concussions than older players.
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Background: Previous studies examining nondisclosure among athletes in various settings have found substantial proportions of athletes with undisclosed concussions. Substantial gaps exist in our understanding of the factors influencing athletes' disclosure of sports-related concussions. Purpose: To examine the prevalence of, and factors associated with, nondisclosure of recalled concussions in former collegiate athletes. Study design: Cross-sectional study; Level of evidence, 3. Methods: Former collegiate athletes (N = 797) completed an online questionnaire. Respondents recalled self-identified sports-related concussions (SISRCs) that they sustained while playing sports in high school, college, or professionally, and whether they disclosed these SISRCs to others. Respondents also recalled motivations for nondisclosure. The prevalence of nondisclosure was calculated among those who recalled SISRCs. Multivariate binomial regression estimated adjusted prevalence ratios (PRs) with 95% CIs, controlling for sex, level of contact in sports, and year the athletes began playing collegiate sports. Results: A total of 214 respondents (26.9%) reported sustaining at least 1 SISRC. Of these, 71 (33.2%) reported not disclosing at least 1 SISRC. Former football athletes were most likely to report nondisclosure (68.3% of those recalling SISRCs); female athletes who participated in low/noncontact sports were the least likely to report nondisclosure (11.1% of those recalling SISRC). The prevalence of nondisclosure was higher among men than women in the univariate analysis (PR, 2.88; 95% CI, 1.62-5.14), multivariate analysis (PR, 2.11; 95% CI, 1.13-3.96), and multivariate analysis excluding former football athletes (PR, 2.11; 95% CI, 1.12-3.94). The most commonly reported motivations were as follows: did not want to leave the game/practice (78.9%), did not want to let the team down (71.8%), did not know it was a concussion (70.4%), and did not think it was serious enough (70.4%). Conclusion: Consistent with previous studies, a substantial proportion of former athletes recalled SISRCs that were not disclosed. Male athletes were less likely to disclose all of their SISRCs than female athletes.
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Background: The epidemiology of sports-related concussion is not well-described in the literature. This paper presents a descriptive epidemiology of concussion in seven high school and collegiate sports. Methods: We used the data from Concussion Prevention Initiative (CPI), which enrolled 8905 athletes at 210 high schools and 26 colleges in a prospective cohort study of 7 sports (football, men’s and women’s soccer, men’s and women’s lacrosse, and men’s and women’s ice hockey) between 1999 and 2001. Injury risks and injury rates were used to characterize the incidence of concussion, and changes in symptoms over time were described. Results: A total of 375 concussions were observed. The incidence of concussion was highest in football, followed by women’s lacrosse, men’s lacrosse, men’s soccer, and women’s soccer (only 10 ice hockey teams were included, too few to quantify incidence). The rate of incident concussion was strongly associated with history of concussion in the previous 24 months (rate ratio = 5.5; 95 %CI: 3.9, 7.8, for 2 or more concussions relative to no previous concussion). The most common symptoms at time of injury were headache (87 %), balance problems/dizziness (77 %), and feeling “in a fog” (62 %). Loss of consciousness and amnesia were present in relatively few cases (9 and 30 %). The most common mechanism of injury was collision with another player. Conclusions: Sports-related concussions present with a diverse range of symptoms and are associated with previous concussion history.
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A report by the Institute of Medicine called for comprehensive nationwide concussion incidence data across the spectrum of athletes aged 5 to 23 years. To describe the incidence of concussion in athletes participating in youth, high school, and collegiate American football. Data were collected by athletic trainers at youth, high school, and collegiate football practices and games to create multiple prospective observational cohorts during the 2012 and 2013 football seasons. Data were collected from July 1, 2012, through January 31, 2013, for the 2012 season and from July 1, 2013, through January 31, 2014, for the 2013 season. The Youth Football Surveillance System included 118 youth football teams, providing 4092 athlete-seasons. The National Athletic Treatment, Injury and Outcomes Network program included 96 secondary school football programs, providing 11 957 athlete-seasons. The National Collegiate Athletic Association Injury Surveillance Program included 24 member institutions, providing 4305 athlete-seasons. All injuries regardless of severity, including concussions, and athlete exposure information were documented by athletic trainers during practices and games. Injury rates, injury rate ratios, risks, risk ratios, and 95% CIs were calculated. Concussions comprised 9.6%, 4.0%, and 8.0% of all injuries reported in the Youth Football Surveillance System; National Athletic Treatment, Injury and Outcomes Network; and National Collegiate Athletic Association Injury Surveillance Program, respectively. The game concussion rate was higher than the practice concussion rate across all 3 competitive levels. The game concussion rate for college athletes (3.74 per 1000 athlete exposures) was higher than those for high school athletes (injury rate ratio, 1.86; 95% CI, 1.50-2.31) and youth athletes (injury rate ratio, 1.57; 95% CI, 1.17-2.10). The practice concussion rate in college (0.53 per 1000 athlete exposures) was lower than that in high school (injury rate ratio, 0.80; 95% CI, 0.67-0.96). Youth football had the lowest 1-season concussion risks in 2012 (3.53%) and 2013 (3.13%). The 1-season concussion risk was highest in high school (9.98%) and college (5.54%) in 2012. Football practices were a major source of concussion at all 3 levels of competition. Concussions during practice might be mitigated and should prompt an evaluation of technique and head impact exposure. Although it is more difficult to change the intensity or conditions of a game, many strategies can be used during practice to limit player-to-player contact and other potentially injurious behaviors.
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Background: Concussions are common in football, and knowledge of their incidence rates across settings is needed to develop strategies to decrease occurrence. Purpose: To examine sports-related concussion rates in a National Collegiate Athletic Association (NCAA) Division I Football Bowl Subdivision sample based on the activity setting where injuries occurred, during which type of play, and when relative to the 2010 NCAA concussion management policy. Study design: Descriptive epidemiology study. Methods: Medical records from January 2006 to January 2015 for an NCAA Division I Football Bowl Subdivision program were analyzed. Concussion rates (per 1000 athlete-exposures [AEs]) were compared among the following settings: spring practice, preseason training camp, regular season high-contact practice, regular season low-contact practice, bowl game practice, and game competition. Play-type analyses examined incidence rates during offensive, defensive, and special teams plays. Changes in concussion rate coinciding with the 2010 NCAA concussion management policy were also studied. Results: Of the 452 unique players on the roster during the 9-year study period, 118 (26.1%) were diagnosed with a concussion. The concussion rate during games was significantly higher than all practices combined (P < .001). However, when game rate (4.46 per 1000 AEs) was compared with preseason training camp alone (3.81 per 1000 AEs), there was no significant difference (P = .433). The concussion rate during special teams plays was significantly higher than that during offensive (P < .001) or defensive plays (P < .001). The concussion rate in the 4 seasons (2010-2014) after the 2010 NCAA concussion management policy was initiated was significantly higher than the 4 seasons (2006-2009) preceding the policy (P = .036). Conclusion: Study results show that (1) based on activity type, games and preseason training camp present the greatest risk of sustaining a concussion; (2) based on play type, special teams plays pose the greatest risk of sustaining a concussion; and (3) the 2010 NCAA concussion management policy coincided with a significant increase in recognition of concussion.
Article
Background: The epidemiology of sports-related concussion (SRC) among student-athletes has been extensively researched. However, recent data at the collegiate level are limited. Purpose: To describe the epidemiology of SRC in 25 National Collegiate Athletic Association (NCAA) sports. Study Design: Descriptive epidemiology study. Methods: SRC data from the NCAA Injury Surveillance Program during the 2009-2010 to 2013-2014 academic years were ana- lyzed. Concussion injury rates, rate ratios (RRs), and injury proportion ratios were reported with 95% CIs. National estimates were also calculated to examine linear trends across time. Results: During the study period, 1670 SRCs were reported, representing a national estimate of 10,560 SRCs reported annually. Among the 25 sports, the overall concussion rate was 4.47 per 10,000 athlete-exposures (AEs) (95% CI, 4.25-4.68). Overall, more SRCs occurred in competitions (53.2%). The competition rate (12.81 per 10,000 AEs) was larger than the practice rate (2.57 per 10,000 AEs) (competition vs practice, RR = 4.99; 95% CI, 4.53-5.49). Of all SRCs, 9.0% were recurrent. Most SRCs occurred from player contact (68.0%). The largest concussion rates were in men’s wrestling (10.92 per 10,000 AEs; 95% CI, 8.62-13.23), men’s ice hockey (7.91 per 10,000 AEs; 95% CI, 6.87-8.95), women’s ice hockey (7.50 per 10,000 AEs; 95% CI, 5.91-9.10), and men’s football (6.71 per 10,000 AEs; 95% CI, 6.17-7.24). However, men’s football had the largest annual estimate of reported SRCs (n = 3417), followed by women’s soccer (n = 1113) and women’s basketball (n = 998). Among all SRCs, a linear trend did not exist in national estimates across time (P = .17). However, increases were found within specific sports, such as men’s football, women’s ice hockey, and men’s lacrosse. Conclusion: The estimated number of nationally reported SRCs has increased within specific sports. However, it is unknown whether these increases are attributable to increased reporting or frequency of concussions. Many sports report more SRCs in practice than in competition, although competition rates are higher. Men’s wrestling and men’s and women’s ice hockey have the highest reported concussion rates. Men’s football had the highest annual national estimate of reported SRCs, although the annual participation count was also the highest. Future research should continue to longitudinally examine SRC incidence while considering differences by sex, division, and level of competition.
Article
Background: High school athletes are at risk for concussions. Although a previously published study showed an increase in concussion rates for a single school district, it remains unknown if the rate of concussions among high school athletes is increasing nationally. Purpose: To investigate national high school athlete concussion rates over time. Study design: Descriptive epidemiologic study. Methods: The rate of concussions per 1000 athlete-exposures was calculated for academic years 2005-2006 through 2011-2012 using the High School Reporting Information Online sports injury surveillance system. Results: During the 7-year period of this study, High School Reporting Information Online captured 4024 concussions with overall concussion diagnosis rates increasing significantly from 0.23 to 0.51 (P = .004). Concussion diagnosis rates increased for each of the 9 sports studied, with 5 sports having statistically significant increases over this 7-year period. Conclusion: The study analysis indicates that national concussion diagnosis rates for high school sports have increased significantly over time.