Female soccer players playing elite or select soccer before high school sustained concussions at a rate higher than their high school and college counterparts, most continued to play despite experiencing symptoms, and less than half sought medical attention, a first-of-its-kind study finds.
Analyzing data collected over a four-year period from 351 players between the ages of 11 and 14 on elite and travel soccer teams, researchers at the University of Washington reported:
- Higher concussion rate than for older athletes: a concussion rate of 1.3 concussions per 1,000 athletic exposures (e.g games or practices) versus .34 concussions per 1,000 AEs in the most recent study of high school soccer players;
- Similar injury mechanisms as older athletes: 54.3% of concussions were the result of player-to-player contact (versus 58.1% for female HS players, 29.8% were from player-ball contact (versus 26.4% for HS players) or the playing surface (15.9% versus 18.2% for HS girls; 
- More concussions during heading: 30.5% occurred during heading (similar to the percentage of 27.7% for high school athletes in the most recent study ), goaltending (11.9%), chasing a loose ball (10.1%), or getting the ball from an opponent (10.1%); Fouls were called in 15.2% of the plays in which concussions occurred;
- Most in games, as with older athletes: Most (86.4%) concussions occurred during a game (consistent with studies finding a 11.5 to 13.7 increased risk during games in older age groups);
- Symptoms similar to those experienced by older athletes: Most common symptoms reported at initial interview:
- headache (89.3%) versus 94.2% for high school athletes in 20 sports
- dizziness (67.8%) versus 75.6% for HS athletes
- concentration problems (42.4%) versus 54.8% for HS athletes
- drowsiness (33.9%)
- nausea (32.2%) versus 31.4% for HS athletes
- light sensitivity (28.8%) versus 36.0% for HS athletes
- irritability (27.1%)
- confusion (23.7%) versus 45.0% for HS athletes
- loss of consciousness (13.6%)
- Recovery time similar to older athletes:
- The median time to concussion recovery (complete resolution of symptoms and return to full participation) was 4.0 days, with a mean of 9.4 days;
- time to symptom resolution:
- 11.9% less than 1 day (versus HS study finding that 27% had resolution by 1 day)
- 52.5% lasting 1 to 7 days (versus HS study finding 77.9% of players returning by 7 days)
- 11.9% lasting 8 to 14 days (versus HS study finding 15.1% with symptoms lasting more than a week but less than a month )
- 15.3% lasting 15 to 21 days and 8.4% lasting more than 21 days (versus HS study finding 15.1% lasting longer than 1 week but less than a month and another finding 19.6% lasting between 1 week and one month)
- symptoms associated with the shortest time to resolution: dizziness (4.5 days); headache (5.0 days); irritability (5.0 days); loss of consciousness (5.5 days)
- symptoms associated with longest time to resolution: light sensitivity (16.0 days); emotional liability (e.g. unsteady emotions or subject to quick change) (15.0 days); confusion (12.0 days); noise sensitivity (12.0 days)
- Concussion symptom duration of more than 1 week more likely in those with greater number of presenting symptoms (consistent with a 2013 study finding an association between four or more symptoms at initial evaluation and symptoms lasting a week or more)
- Majority never evaluated:
- More than half (55.9%) of the players reporting concussion symptoms were never evaluated;
- Among the 44.1% who were examined by a QHP, 76.9% were diagnosed with a concussion;
- players who were evaluated by a qualified health care professional (e.g. physician, nurse practitioner, physician assistant, or certified athletic trainer)(QHP) were symptomatic significantly longer (11.5 days versus 2 days) and less likely to play with symptoms (42.3% versus 71.9%) compared with those who were not evaluated.
- Percentage that kept playing with concussion symptoms higher than previously reported:
- 58.6% reported playing soccer while symptomatic (higher than studies of high school and college athletes finding between one-third and one-half reporting concussion symptoms for which they did not seek medical attention, largely because did not appreciate significance of injury or feared being withheld from play);
- players who did not continue playing with concussion symptoms cited concern for making symptoms worse (39.0%) and advice from a health care professional (25.8%), parent (35.6%), or coach (28.8%).
The study's authors offered several possible explanations for the concussion rate in female middle school soccer players four times higher than in the most recent study of female high school soccer players. They could be explained, said lead author, John O'Kane, MD, of the University of Washington Sports Medicine Clinic, by differences in methodology (prospective data collection with weekly interviews in the current study versus data reported by athletic trainers in the other studies), and under-reporting in previous studies that captured concussions only in athletes seeking medical attention.
Noting other studies finding that between one-third and one-half of players report concussion symptoms for which they did not seek medical attention, and the fact that, in the current study, only 44.1% of athletes identified through the weekly interviews sought medical evaluation by a QHP, and that the concussion rate considering only those diagnosed by a QHP was far lower than the overall rate reported (.4 per 1,000 AEs versus 1.3 per 1,000 AEs). "We suspect that underreporting in previous studies explains the lower rates observed," said Dr. O'Kane.
Playing with concussion symptoms: reason for concern
The high percentage of athletes reporting that they continued to play despite experiencing concussion symptoms, while similar to the rates reported in other studies, is concerning, as the failure to diagnose concussions in athletes can lead to further damage to the brain before full recovery, expose them to the cumulative effects of injuries and increased risk of second impact syndrome. [5-7]
"The fact that 58% of athletes continued to play with their concussion symptoms is troubling," said Tracey Covassin PhD, ATC, and Associate Professor and Undergraduate Athletic Training Program Director at Michigan State University, and an expert in sport-related concussions; "not from a research perspective but from an educational perspective and safety concern for the athletes. I feel like we are trying to educate athletes on the signs and symptoms of concussion and dangers of playing with a concussion, but either we are not reaching everyone (which is true) or athletes are continuing to hide their symptoms so they can continue to play."
While O'Kane said there was some evidence that concussion education could improve the percentage of athletes reporting concussions, pointing to a 2012 study finding that high school athletes receiving concussion education were twice as likely to report symptoms to coaches compared with those with no education (72% vs. 36%), he acknowledged that a 2013 study (also by researchers at the University of Washington) found that many high school soccer players, despite understanding the symptoms of concussion and the potentially severe complications from playing with concussion, would continue to play despite symptoms.
Besides the 2013 University of Washington study, a number of other recent studies have found education ineffective in improving self-reporting by athletes, adding to a growing body of evidence challenging the conventional wisdom that inadequate athlete concussion knowledge is the principal barrier to increased reporting, and suggesting that one of the best ways to combat underreporting by athletes of concussion symptoms may be to shift the focus of educational efforts towards helping coaches facilitate concussion reporting, the theory being that athletes will be more likely to report concussion symptoms if they no longer think that they will be punished by the coach for reporting, such as by losing playing time or their starting position, perceived by their teammates as letting them down, or viewed by their coach as "weak," all of which have been documented in numerous studies over the past decade as reasons athletes are reluctant to report concussion symptoms.[8-17]
Dr. O'Kane and his colleagues recognized that the study had several limitations;
- the number of concussions might have been overstated because it was unclear how many of the participants reporting concussion symptoms might have had a different diagnosis if formally evaluated. The risk of misclassification was minimized, he said, through the use of a standard definition of concussion and concussion symptom scale validated in previous studies in discriminating between concussed and non-concussed, and by having an experienced sports medicine physician review all reports;
- Conversely, the number and rates of concussions might have been underreported because the Internet surveillance system utilized required parents to be aware of their daughters' symptoms to be able to report them, although O'Kane pointed out that the surveillance system used had been shown in a previous study to be equivalent to the High School RIO, the certified athletic training reporting system used to track concussions in high school athletes.
- It was also possible, he said, that concussion symptoms may have resolved while an objective assessment (such as of balance, or neurocognitive function) might have revealed persistent deficits. (Indeed, studies have shown that self-assessments by athletes of recovery may be unreliable).
"I think the biggest limitation with the study was that parents reported their child's concussion," said Dr. Covassin. "However, due to the parent not being qualified to diagnose a concussion, I think the prevalence and injury rate would have been higher if they had a certified athletic trainer present for practices and games."
"I have great respect for the researchers at Harborview and think this was a good study, and was great to see somebody providing data on youth younger than high school age," said Dawn Comstock, an epidemiologist at the Colorado School of Public Health who has studied extensively sports injuries at the high school level.
"That said, Comstock said that, as with all studies, there were a few methodological issues. "First, this is relatively small regional sample from a population with which this group has done quite a bit of work, so these parents may be more knowledgeable about concussions than other parents across the country." Second, like Dr. Covassin, she noted that it was based on a parent report of concussion symptoms, with about half of the reported cases never diagnosed by a medical professional. As a result, Comstock said, while the authors discuss the possibility of under-reporting in other studies, she was "more concerned with over-reporting in this study."
Finally, she noted that "the researchers never tell us how many of the heading-related concussions were from athlete-athlete contact versus contact with the ball versus contact with the ground. "This is disappointing, Comstock said, "since they had the data and just didn't present it," an omission that she felt was was "really important from a prevention standpoint: if we want to significantly reduce concussions in youth soccer, [we need to know] do we need to ban heading altogether, or would we be successful if rules prohibiting athlete-athlete contact during heading were enacted and strictly enforced?"
Three takeaway points
In the final analysis, says Dr. Covassin, the current study "demonstrates three things: First, we need to conduct better education for the younger population on the signs and symptoms of concussion. Second, we need to do a better job on educating players on the dangers of playing with a concussion, especially in this younger population. And, third, we need to conduct more research on youth athletes (5-13 years old) and female athletes."
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