Epidemiology of Sport-Related Concussion

Sport-related concussions are common in the United States. Concussion rates have increased over time, likely due to improved recognition and awareness. Concussion rates vary across level (high school vs college), sex, and sport. Concussion rates are the highest among men, particularly in football, wrestling, ice hockey, and lacrosse where collisions and contact are inherent to the sports, although girls’/women’s soccer rates are high. In gender-comparable sports, women have higher concussion rates. Continued data collection will increase understanding of sport-related concussion and provide areas for targeted prevention in the future.

Key points

•

Concussion rates vary across sport and age, with college athletes generally having higher concussion rates than high school athletes.
•

Across gender-comparable sports, females have higher concussion rates than males in both college and high school.
•

Concussion rates have increased over time, likely due to an increase in awareness and recognition.
•

Although data collection efforts have improved over time, continued and increased data collection is necessary to fully understand the burden of sport-related concussion.

Introduction

Participation in sports occurs across the life span. In 2018, 56% of children aged 6 to 12 years in the United States played a team sport, with 38% of these children participating on a regular basis. In addition to club sports and travel leagues, during the 2018/19 academic year, 7.9 million athletes participated in school-sanctioned high school sports, and more than 500,000 collegiate athletes participated in National Collegiate Athletic Association (NCAA) championship and emerging sports. ^, Approximately 1 in 4 adults in the United States (US) play sports, with 18% of adults participating in sports and exercise on an average day. ^, Table 1 presents changes in participation numbers between the 2009/10 and 2018/19 seasons for select high school and college sports.

Table 1

Participation changes 2009/10 and 2018/19 by sport and sex for select high school and college sports

Data from National Federation of State High School Associations. 2018-19 High School Athletics Participation Survey. 2019; https://www.nfhs.org/media/1020412/2018-19_participation_survey.pdf . Accessed 11/27/2019 and National Collegiate Athletic Association. NCAA Sports Sponsorship and Participation Rates Report Student-Athlete Participation 1981-82 – 2018-19 2019; https://ncaaorg.s3.amazonaws.com/research/sportpart/2018-19RES_SportsSponsorshipParticipationRatesReport.pdf . Accessed 11/27/2019.

		High School ^a			College ^a
		2009/10	2018/19	% Change	2009/10	2018/19	% Change
Men’s sports	American football	1,109,278	1,006,013	−9%	66,313	73,712	11%
	Baseball	472,644	482,740	2%	30,365	36,011	19%
	Basketball	540,207	540,769	0%	17,008	18,816	11%
	Ice hockey	36,475	35,283	−3%	3945	4323	10%
	Lacrosse	90,670	113,702	25%	9844	14,603	48%
	Soccer	391,839	459,077	17%	21,770	25,499	17%
	Wrestling	272,890	247,441	−9%	6397	7300	14%
Women’s sports	Basketball	439,550	399,067	−9%	15,423	16,509	7%
	Field hockey	63,719	60,824	−5%	5634	6119	9%
	Lacrosse	68,768	99,750	45%	7683	12,452	62%
	Soccer	356,116	394,105	11%	23,650	28,310	20%
	Softball	391,776	368,640	−6%	17,726	20,419	15%
	Volleyball	403,985	452,808	12%	15,133	17,780	17%
Co-ed ^b	Cheerleading	126,390	165,296	31%

a High school data from the annual NFHS participation report; college data from the annual NCAA participation report.

b Cheerleading is not an NCAA-sanctioned sport.

Being active in sports is one way to maintain a physically fit, healthy lifestyle. In addition to helping maintain a healthy weight, sports participation can increase strength, endurance, and flexibility. ^, Regular physical activity has also been shown to improve psychological well-being, increase self-esteem, reduce depression and anxiety, and improve academic performance. ^,

Despite the numerous health benefits, athletes are at risk of sports-related injury, as a certain endemic level of injury can be expected among participants of any physical activity. A wide variety of injuries occur during sports participation including concussion, the definition of which may vary across studies. The Berlin Consensus Statement on Concussion in Sport defines a sports-related concussion as a “traumatic brain injury (TBI) induced by biomechanical forces.” The Centers for Disease Control and Prevention defines a concussion as a “type of TBI caused by a bump, blow, or jolt to the head or by a hit to the body that causes the head and brain to move rapidly back and forth.” A concussion results in a range of clinical symptoms that vary individual to individual that may or may not include a loss of consciousness. Most symptoms of concussion resolve in 1 to 3 weeks; however, some symptoms may persist for a month or longer.

The burden of sports-related concussion has been measured in various settings, such as emergency departments (EDs), hospitals/inpatient, clinics, schools, and sports organizations. One study found that an estimated 283,000 children aged 18 years and younger are treated in US EDs for a sports- or recreation-related TBI each year. In 2017, 2.5 million high school students reported sustaining at least one sport or activity-related concussion in the past year, and one million high school students reported sustaining more than one sport- or activity-related concussion in the past year. Of the 3.42 million sports- and recreation-related TBIs seen in US ED from 2001 to 2012, 30% occurred among adults aged 20 years and older. The incidence of concussion is certainly underestimated, as these numbers do not include concussions in which the injured athlete did not seek medical treatment or the concussion was not properly diagnosed. Current data sources may capture only 1 out of every 9 concussions sustained in the United States.

Just as the definition of concussion and source of data varies from study to study, so does how the burden of concussion was measured. The most commonly used metric of injury occurrence in sports injury research is a rate or the total number of injuries divided by some measure of exposure such as team-season, team-games, player-season, player-games, player-minutes, player-plays, or athlete-exposure. Other common metrics used in sports injury research include injury risk and injury odds. Injury risk is calculated as the number of injured athletes in a given time period divided by the number of athletes at risk of being injured in the same time period. Odds of injury, which is a function of risk, is calculated by dividing the risk of injury by one minus the risk. When making direct comparisons of results across studies, it is important to consider how the burden of concussion was measured.

Recently, direct comparisons between sports and age groups were made possible through data collected via 2 national sports injury surveillance systems, High School Reporting Information Online (RIO) and the NCAA Injury Surveillance Program (NCAA-ISP). Both systems are web-based and rely on athletic trainers to enter in injury and athlete exposure (AE) information on a weekly basis. Tables 2 and 3 display comparative data collected during the 2004/05 to 2013/14 seasons. National estimates of concussions presenting to US EDs are also available from the National Electronic Injury Surveillance System (NEISS) using a nationally representative sample of 100 US hospitals with EDs.

Table 2

Concussion rates per 10,000 AE and rate ratios comparing competitions versus practices in high school and college sports

		High School ^a				College ^a
		Overall Rate	Competition Rate	Practice Rate	Rate Ratio Competition vs Practice (95% CI)	Overall Rate	Competition Rate	Practice Rate	Rate Ratio Competition vs Practice (95% CI)
Men’s sports	American football	7.28	25.73	3.54	7.27 (6.78, 7.79)	6.31	30.09	3.99	7.53 (6.89, 8.24)
	Baseball	0.69	1.33	0.34	3.87 (2.59, 5.79)	1.13	2.25	0.53	4.22 (2.70, 6.58)
	Basketball	1.53	3.27	0.79	4.14 (3.27, 5.23)	6.18	12.62	4.52	2.79 (2.35, 3.32)
	Ice hockey	6.83	17.66	1.50	11.74 (8.24, 16.72)	6.95	22.88	2.06	11.12 (8.76, 14.12)
	Lacrosse	4.87	12.18	1.63	7.46 (5.76, 9.66)	4.51	16.98	2.19	7.75 (5.74, 10.47)
	Soccer	2.78	7.68	0.68	11.28 (8.81, 14.45)	4.02	12.36	1.73	7.16 (5.58, 9.19)
	Wrestling	3.13	5.85	2.17	2.70 (2.24, 3.25)	6.72	27.95	4.10	6.81 (5.05, 9.18)
Women’s sports	Basketball	2.98	7.39	1.08	6.82 (5.55, 8.38)	4.99	9.99	3.54	2.82 (2.31, 3.44)
	Field hockey	2.67	5.94	1.16	5.14 (3.63, 7.29)	4.19	11.29	1.86	6.08 (3.80, 9.73)
	Lacrosse	3.67	8.34	1.57	5.33 (3.85, 7.36)	5.07	14.23	2.88	4.94 (3.56, 6.83)
	Soccer	4.50	12.84	0.92	13.92 (11.13, 17.40)	6.44	19.11	2.33	8.19 (6.73, 9.98)
	Softball	1.40	2.20	0.97	2.26 (1.66, 3.07)	2.61	4.19	1.50	2.80 (2, 3.92)
	Volleyball	1.18	1.90	0.80	2.39 (1.77, 3.23)	2.29	3.26	1.88	1.73 (1.22, 2.46)

High School Reporting Information Online (2005/06–2013/14) and the National Collegiate Athletic Association Injury Surveillance Program (2004/05–2013/14).

Abbreviations: AE, athlete exposure, one athlete participating in one practice or competition; CI, confidence interval.

a HS RIO and the NCAA-ISP collect injury and exposure data from national samples of high school and collegiate sports programs, respectively. Data presented in this table were collected from each surveillance system during the same time periods. HS RIO began data collection of lacrosse, ice hockey, and field hockey in 2008/09.

Table 3

Concussion numbers and percentage of all practice and competition injuries in high school and college sports

		High School ^a				College ^a
		Practice		Competition		Practice		Competition
		n	%	n	%	n	%	n	%
Men’s sports	American football	1337	15.8	1966	20.4	1136	8.4	834	9.4
	Baseball	35	5.1	74	8.8	28	2.5	63	4.4
	Basketball	110	7.2	192	12.6	312	10.3	225	14.3
	Ice hockey	36	21.8	208	31.4	87	10.1	297	17.0
	Lacrosse	75	13.8	248	28.8	72	6.3	104	14.3
	Soccer	76	6.6	366	20.9	93	3.8	183	7.9
	Wrestling	226	11.3	218	15.9	94	5.9	79	10.1
Women’s sports	Basketball	122	9.6	357	21.7	215	8.7	176	12.4
	Field hockey	45	8.8	107	22.7	26	4.3	52	13.3
	Lacrosse	52	15.2	125	35.0	67	10.2	79	21.2
	Soccer	90	8.6	537	24.5	136	5.2	361	14.6
	Softball	75	11.5	89	12.8	51	5.4	100	11.0
	Volleyball	77	7.8	96	15.1	75	5.0	54	8.5