Association between days for concussion recovery and initial specialty clinic evaluation within 48 hours.

BACKGROUND: Researchers have highlighted the importance of early access to concussion care within one week of injury in reducing recovery times. However, a persisting question for concussion researchers is "just how early is important?" The purpose of this study was to examine differences in recovery time as predicted by the number of days elapsed since injury (DSI) to initial evaluation among patients who had access to a specialty concussion clinic within seven days. We hypothesized that DSI group membership, even within seven days, would significantly predict risk of protracted recovery (i.e., beyond 21 days). METHODS: In this archival study, retrospective data were gathered from electronic medical records between September 2020 to March 2022. Records of participants between ages 12-18, those diagnosed with a sports-related concussion based on initial clinic visit diagnosis by a medical provider and those who established care within seven days of injury at a large pediatric specialty concussion clinic were examined. Participants were divided into three DSI groups (patients seen in < 48 h: "acute", patients seen between 49 h < and < 96 h: "sub-acute", and patients seen between 97 < and < 168 h: "post-acute"). A general linear model was constructed to examine relationships between relevant concussion factors (e.g., Post Concussion Scale Score, neurodevelopmental history, psychiatric history, concussion history, migraine history, overall VOMS change score, cognitive testing, sex, age, race, and ethnicity) that were either significant in the preliminary analysis or in clinical judgement and recovery time. Adjusted odds ratios (OR) were derived from a binary logistic regression model, in which recovery time was normal (≤ 21 recovery days) or protracted (> 21 recovery days). RESULTS: A total of 856 participants were eligible. Adolescents in the acute group (M = 15.12, SD = 8.04) had shorter recovery times in days compared to those in the sub-acute (M = 17.98, SD = 10.18) and post-acute (M = 21.12, SD = 10.12; F = 26.00, p < .001) groups. Further, participants in the acute (OR = 4.16) and sub-acute (OR = 1.37) groups who accessed specialty concussion clinics within 48 h were 4 times more likely to have a normal recovery and recovered approximately 6 days faster than the post-acute care group. CONCLUSIONS: Earlier concussion care access predicted recovery times and was associated with lower risk for protracted recovery.

Prospective evaluation of 24-hour movement behaviors among adolescents recovering from a sport-related concussion.

This study aimed to describe the 24-hour composition of movement behaviors, including sleep, sedentary behavior, and physical activity (PA), among pediatric sports-related concussion (SRC) patients over their recovery period, assess the association between movement compositions and recovery time, and understand feasibility of 24-hour accelerometry in the study population. A cohort of 50 pediatric SRC patients were asked to wear a wrist-worn accelerometer continuously for the duration of their recovery. Among all enrolled participants, the sample was primarily 14 or 15 years of age (65%), female (55%), and recovered in under 28 days (88%). Accelerometer compliance was moderate; 35 participants (70%) were compliant with the protocol. Compositional analysis was used to address time-use objectives in 33 participants who provided adequate data for inclusion. Overall, participants spent an average of 50% of their 24-hour day sedentary, 33% sleeping, 11% in light intensity PA, and 6% in moderate or vigorous intensity PA. The 24-hour composition of movement behaviors was not associated with recovery time (p = .09-.99). However, the limited sample size may have contributed to null findings. Given recent evidence supporting the effects of sedentary behavior and PA on concussion recovery, future studies should aim to further validate these findings in a larger sample.

Comparison of Prescribed Physical Therapy to a Home Exercise Program for Pediatric Sports-Related Concussion Patients.

The purpose of this retrospective chart review was to compare sports-related concussion (SRC) recovery time in protracted recovery (≥28 days) patients who were prescribed physical therapy (PPT) with those who were only provided a home exercise program (HEP). We hypothesized PPT would be associated with shorter recovery times relative to HEP. Associations were evaluated with multivariable zero-truncated negative binomial regressions. Among the 48 (30.2%) PPT and 111 (69.8%) HEP patients, the majority were female (57.9%), the mean age was 15.3 ± 1.4 (PPT) and 14.2 ± 2.8 (HEP), and time to clinic was a median 6.0 (IQR = 3.0-27.0; PPT) and 7.0 (IQR = 3.0-23.0; HEP) days. After adjusting for demographic (age, sex) and clinical measures (concussion history, convergence, VOMS, PCSS score, and days to clinic), PPT unexpectedly was associated with 1.21 (95% CI: 1.05, 1.41) additional recovery days compared with HEP. One reason for this could be related to patients adhering to the number of a priori prescribed PT sessions which may or may not have aligned with the patient's symptom resolution. Future research should explore this hypothesis while aiming to evaluate the effect of PPT versus HEP using a randomized design. If confirmed, these findings are encouraging for patients who could not otherwise access or afford specialty rehabilitation.

Machine learning to predict sports-related concussion recovery using clinical data.

OBJECTIVES: Sport-related concussions (SRCs) are a concern for high school athletes. Understanding factors contributing to SRC recovery time may improve clinical management. However, the complexity of the many clinical measures of concussion data precludes many traditional methods. This study aimed to answer the question, what is the utility of modeling clinical concussion data using machine-learning algorithms for predicting SRC recovery time and protracted recovery? METHODS: This was a retrospective case series of participants aged 8 to 18 years with a diagnosis of SRC. A 6-part measure was administered to assess pre-injury risk factors, initial injury severity, and post-concussion symptoms, including the Vestibular Ocular Motor Screening (VOMS) measure, King-Devick Test and C3 Logix Trails Test data. These measures were used to predict recovery time (days from injury to full medical clearance) and binary protracted recovery (recovery time > 21 days) according to several sex-stratified machine-learning models. The ability of the models to discriminate protracted recovery was compared to a human-driven model according to the area under the receiver operating characteristic curve (AUC). RESULTS: For 293 males (mean age 14.0 years) and 362 females (mean age 13.7 years), the median (interquartile range) time to recover from an SRC was 26 (18-39) and 21 (14-31) days, respectively. Among 9 machine-learning models trained, the gradient boosting on decision-tree algorithms achieved the best performance to predict recovery time and protracted recovery in males and females. The models' performance improved when VOMS data were used in conjunction with the King-Devick Test and C3 Logix Trails Test data. For males and females, the AUC was 0.84 and 0.78 versus 0.74 and 0.73, respectively, for statistical models for predicting protracted recovery. CONCLUSIONS: Machine-learning models were able to manage the complexity of the vestibular-ocular motor system data. These results demonstrate the clinical utility of machine-learning models to inform prognostic evaluation for SRC recovery time and protracted recovery.

Exploring Vestibular/Ocular and Cognitive Dysfunction as Prognostic Factors for Protracted Recovery in Sports-Related Concussion Patients Aged 8 to 12 Years.

OBJECTIVE: To explore the prognostic ability of the vestibular/ocular motor screening (VOMS), King-Devick (K-D) Test, and C3 Logix Trails A and B to identify protracted recovery from sports-related concussion (SRC) in patients aged 8 to 12 years. DESIGN: Retrospective cohort analysis. SETTING: Specialty pediatric sports concussion clinic. PARTICIPANTS: A total of 114 youth athletes aged 8 to 12 years who were diagnosed with an SRC within 7 days of injury. INDEPENDENT VARIABLES: A positive screen on the VOMS, K-D, and C3 Logix Trails A and Trails B. Combined positive screens on multiple tests (ie, 2, 3, or all 4 positive screens of 4 possible). MAIN OUTCOME MEASURES: Recovery time in days and protracted recovery (recovery time ≥30-days) were the primary outcomes of interest. RESULTS: A positive VOMS screen was associated with 1.31 greater days to SRC recovery ( P = 0.02) than a negative VOMS screen. The K-D and C3 Logix tests were not significantly associated with recovery time, nor were any combinations of tests ( P > 0.05). The VOMS demonstrated moderate prognostic ability to predict normal recovery (negative predictive value = 80.78% [95% CI = 63.73-90.95]). Overall predictive accuracy of normal versus protracted recovery was strongest when a participant screened positive on all 4 tests (Accuracy = 76.32% [95% CI = 67.45-83.78]). CONCLUSIONS: The VOMS was associated with overall recovery time and proved to be a useful test to identify those who would experience a normal recovery time. Combining the 4 tests improved the prognostic accuracy of the protocol in predicting protracted versus normal recovery. These findings suggest that combining multiple, varied assessments of cognition and vestibular/ocular functions may better explain factors contributing to protracted recovery.

Evaluation of the vestibular and ocular motor screening (VOMS) as a prognostic tool for protracted recovery following paediatric sports-related concussion.

OBJECTIVE: To understand the relationship between initial vestibular and ocular motor screening (VOMS) and recovery time, and the utility of VOMS to screen for protracted recovery in youth/adolescent patients with sport-related concussion (SRC). METHODS: Participants (8-18 years) who were diagnosed with an SRC within 7 days of the injury were administered the VOMS test by certified medical personnel. Recovery time (days) and protracted recovery (>30 days) were the primary outcomes. Multivariable regression models were used to evaluate the association between VOMS symptom provocation and (1) recovery time (days) and (2) protracted recovery. Measures of VOMS validity, predictive ability and receiver operator curves were used to assess VOMS as a prognostic tool to accurately classify a normal/protracted recovery. RESULTS: After adjustment, any symptom provocation across all VOMS domains was associated (p<0.05) with greater recovery time, except the convergence test (p=0.08) in females. All VOMS test thresholds (≥1 to ≥10) in males and (≥1 to ≥5) in females were associated (p<0.05) with recovery time. However, the VOMS test performed poorly among males (receiver operating characteristic (ROC) area=0.66) and failed among females (ROC area=0.56) as a prognostic tool to identify those that will have a normal/protracted recovery. CONCLUSION: In this sample, overall, the VOMS test was associated with recovery time (days); however, the VOMS was not a valid stand-alone prognostic tool to identify a delayed recovery, but may be useful in combination with other concussion symptomology assessments. Future studies should confirm these findings in larger samples while taking into consideration other comorbid factors that may influence recovery time.

Association Between Concussion History and Factors Relating to Cognitive, Behavioral, and Emotional Health Among American High School Athletes: A Cross-sectional Analysis.

BACKGROUND: The cognitive, behavioral, and emotional deficits that may be associated with sports-related concussions among adolescents are unclear. PURPOSE: To examine the association between reported concussion history and factors relating to cognitive, behavioral, and emotional health among a population-based sample of US high school-aged adolescents. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Participants included a representative sample of US high school student-athletes who reported a concussion history (in the past 12 months) and relevant behaviors/outcomes within 3 domains: cognitive (academics, difficulty concentrating), behavioral (drinking and driving, carrying a weapon, physically fighting, tobacco use, marijuana use, binge drinking), and emotional (symptoms of depression, suicidal thoughts/actions). The adjusted relative odds of experiencing 0 and at least 1, 2, 3, or ≥4 concussions were modeled while mutually adjusting for the behaviors of interest in addition to age, race/ethnicity, and sleep problems. Data were reported in sex stratum. RESULTS: A total of 13,268 participants were included in the unweighted data set. Overall, 14.5% (95% CI, 12.9%-16.2%) of female and 18.1% (95% CI, 16.4%-19.8%) of male student-athletes had at least 1 concussion in the past 12 months. As compared with those who reported not engaging in any of the behaviors deleterious to health or having had any of the negative health outcomes (composite score of 0), female athletes with composite scores of 1 to 4, 5 to 7, and 8 to 11 were 1.94 (95% CI, 1.55-2.43), 3.13 (95% CI, 2.30-4.33), and 6.05 (95% CI, 3.75-9.75) times more likely to have a recent history of concussions after accounting for relevant factors. As compared with those having a composite score of 0, male athletes with composite scores of 1 to 4, 5 to 7, and 8 to 11 were 2.03 (95% CI, 1.58-2.59), 3.80 (95% CI, 2.71-5.34), and 8.23 (95% CI, 4.91-13.77) times more likely to have a recent history of concussions after accounting for relevant factors. CONCLUSION: Self-reported concussions among US high school athletes is related to several deleterious health behaviors and outcomes. These associations should be confirmed in longitudinal analyses.

Management and Treatment of Concussions via Tele-Concussion in a Pediatric Setting: Methodological Approach and Descriptive Analysis.

BACKGROUND: Approximately 2 million children in the United States sustain a concussion annually, resulting in an economic impact as high as US $20 billion. Patients who receive treatment at concussion specialty clinics, versus primary care, experience faster recovery, thereby reducing patient burden and subsequent medical-related costs. Accessibility to specialty clinics is typically limited by the availability of in-office visits. This is particularly relevant in light of the severe acute respiratory syndrome coronavirus 2 pandemic and subsequent guidance to eliminate all non-medically necessary in-clinic visits. Telehealth has been used to effectively deliver in-clinic care across several disciplines including psychiatry, psychology, and neuropsychology. However, a model of telehealth delivered concussion assessment, treatment, and management has not been established. OBJECTIVE: The purposes of this paper are to describe a pediatric concussion specialty clinic's experiences in delivering telehealth concussion services and to provide preliminary descriptive data on a sample of pediatric telehealth patients with concussions. METHODS: The specialty pediatric concussion clinic described here began providing telehealth services in 2019 and is part of the largest and fastest-growing telehealth hospital network in the United States. The clinical care process will be described, including accessing the telehealth platform, assessment during the initial appointment, injury management including communication with relevant patient stakeholders (eg, parent or guardians, athletic trainers), dissemination of rehabilitation exercises, and nature of follow-up visits. Descriptive data will include patient demographics, the radius of care, the time between the date of injury and initial visit, the average number of follow-up visits, and days until medically cleared for return-to-learn and return-to-play. RESULTS: The analytic sample included 18 patients with concussions who were seen for all of their visits via telehealth between August 2019 and April 2020. The mean age of the sample was 14.5 (SD 2.5) years. The radius of care was a median of 17 (IQR 11.0-31.0) miles from the clinic with a median time between injury and the first visit of 21 (IQR 6.0-41.5) days. The mean number of visits was 2.2 (SD 0.8) with a median days between visits of 5.4 (IQR 3.0-9.3) to manage and treat the concussion. Of the 18 patients, 55.6% (n=10) were medically cleared for return-to-learn or -play in a median of 15.5 (IQR 11.0-29.0) days. CONCLUSIONS: Limited access to health care is a well-understood barrier for receiving quality care. Subsequently, there are increasing demands for flexibility in delivering concussion services remotely and in-clinic. This is the first paper to provide a clinically relevant framework for the assessment, management, and treatment of acute concussion via telehealth in a pediatric population.

Microhemorrhages in Professional Motocross Athletes: A Case Series.

Introduction: Motocross is a sport in which riders race 250-450 cc four-stroke dirt bikes and are potentially subjected to a high frequency of head injuries starting at a very young age. The objective of this case series is to present the findings following gradient echo T2-weighted MRI (SWI) upon clinical evaluation after a concussion in 4 young professional motocross racers. Clinical Findings: Microhemorrhages were found in 2 of 4 riders. Areas of microhemorrhages were not aligned with a previously positive CT finding from a prior concussion in 1 rider. Conclusions: Microhemorrhages were found in 2 young motocross riders following a gradient echo T2-weighted MRI upon a clinical evaluation after a concussion. Long-term consequences of these findings are not yet known, and longitudinal studies are needed to provide further understanding to improve concussion management in motocross athletes.

A Physiologically Based Approach to Prescribing Exercise Following a Sport-Related Concussion.

Clinical management of concussion has evolved over the last 20 years, and complete cognitive and physical rest remains a common clinical recommendation. The duration of rest may vary widely, from 24-48 h to several weeks or until the patient's symptoms have resolved or returned to near baseline levels. Following a period of rest, a stepwise progression of exercise is used for gradual return to play or to work. Previous research in healthy people suggested that prolonged periods of physical inactivity consistently induced deleterious physiological and psychological effects. A growing body of evidence indicates that initiating exercise earlier in the recovery process following a concussion may reduce symptom burden and lower the incidence of post-concussion syndrome. Preliminary findings appear promising, but data on the appropriate exercise prescription for patients who recently sustained a concussion are limited. We reviewed the literature in healthy individuals and patients with concussion and post-concussion syndrome to develop a physiologically based exercise prescription for the days following a concussion. Using this, practitioners may shorten the rest period and initiate controlled exercise earlier during the recovery process following a concussion.

Test Performance and Test-Retest Reliability of the Vestibular/Ocular Motor Screening and King-Devick Test in Adolescent Athletes During a Competitive Sport Season.

BACKGROUND: The Vestibular/Ocular Motor Screening (VOMS) and King-Devick (K-D) test are tools designed to assess ocular or vestibular function after a sport-related concussion. PURPOSE: To determine the test-retest reliability and rate of false-positive results of the VOMS and K-D test in a healthy athlete sample. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: Forty-five healthy high school student-athletes (mean age, 16.11 ± 1.43 years) completed self-reported demographics and medical history and were administered the VOMS and K-D test during rest on day 1 (baseline). The VOMS and K-D test were administered again once during rest (prepractice) and once within 5 minutes of removal from sport practice on day 2 (removal). The Borg rating of perceived exertion scale was administered at removal. Intraclass correlation coefficients were used to determine test-retest reliability on the K-D test and the average near point of convergence (NPC) distance on the VOMS. Level of agreement was used to examine VOMS symptom provocation over the 3 administration times. Multivariate base rates were used to determine the rate of false-positive results when simultaneously considering multiple clinical cutoffs. RESULTS: Test-retest reliability of total time on the K-D test (0.91 [95% CI, 0.86-0.95]) and NPC distance (0.91 [95% CI, 0.85-0.95]) was high across the 3 administration times. Level of agreement ranged from 48.9% to 88.9% across all 3 times for the VOMS items. Using established clinical cutoffs, false-positive results occurred in 2% of the sample using the VOMS at removal and 36% using the K-D test. CONCLUSION: The VOMS displayed a false-positive rate of 2% in this high school student-athlete cohort. The K-D test's false-positive rate was 36% while maintaining a high level of test-retest reliability (0.91). Results from this study support future investigation of VOMS administration in an acutely injured high school athletic sample. Going forward, the VOMS may be more stable than other neurological and symptom report screening measures and less vulnerable to false-positive results than the K-D test.

Comparison of baseline ImPACT performance in amateur motocross riders to football and basketball athletes.

PRIMARY OBJECTIVE: The American Motorcyclist Association requires professional riders to undergo baseline computerized neurocognitive testing (CNT) using the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) test for concussion management. It is recommended this practice be expanded to the amateur level, but limited research has explored whether baseline testing is necessary for youth when normative data is available. This study evaluates the utility of baseline testing for amateur riders by comparing their performance to those of traditional youth sports comprising normative datasets. DESIGN/METHODS: An cross-sectional study comparing amateur motocross (N = 100) riders matched by age and sex to football (N = 100) and basketball (N = 100) athletes performance on baseline ImPACT testing. RESULTS: ANCOVAs revealed a significant medium effect of group on measures of visual motor speed (F = 11.25, p < 0.001) and reaction time (F = 13.61, p < 0.001). Post hoc analyses revealed that motocross riders were significantly slower compared to football and basketball athletes. There were no significant differences (p > .05) between sport on measures of memory or symptoms. CONCLUSIONS: Youth motocross riders performed significantly slower on speed measures compared to football and basketball athletes, providing preliminary support for the expansion of baseline ImPACT testing to the amateur level.

Removal From Play After Concussion and Recovery Time.

OBJECTIVE: Despite increases in education and awareness, many athletes continue to play with signs and symptoms of a sport-related concussion (SRC). The impact that continuing to play has on recovery is unknown. This study compared recovery time and related outcomes between athletes who were immediately removed from play and athletes who continued to play with an SRC. METHODS: A prospective, repeated measures design was used to compare neurocognitive performance, symptoms, and recovery time between 35 athletes (mean ± SD age, 15.61 ± 1.65 years) immediately removed after an SRC (REMOVED group) compared with 34 athletes (mean ± SD age, 15.35 ± 1.73 years) who continued to play (PLAYED group) with SRC. Neurocognitive and symptom data were obtained at baseline and at 1 to 7 days and 8 to 30 days after an SRC. RESULTS: The PLAYED group took longer to recover than the REMOVED group (44.4 ± 36.0 vs 22.0 ± 18.7 days; P = .003) and were 8.80 times more likely to demonstrate protracted recovery (≥21 days) (P < .001). Removal from play status was associated with the greatest risk of protracted recovery (adjusted odds ratio, 14.27; P = .001) compared with other predictors (eg, sex). The PLAYED group exhibited significantly worse neurocognitive and greater symptoms than the REMOVED group. CONCLUSIONS: SRC recovery time may be reduced if athletes are removed from participation. Immediate removal from play is the first step in mitigating prolonged SRC recovery, and these data support current consensus statements and management guidelines.

Assessing Symptoms in Adolescents Following Sport-Related Concussion: A Comparison of Four Different Approaches.

This study compared post-concussion symptom endorsements on the Post-Concussion Symptom Scale (PCSS) between a clinical open-ended interview, clinician-guided PCSS, parent-report PCSS, and computer-based PCSS in youth athletes with sport-related concussion (SRC). Participants included 54 patients aged 13-17 years (M = 15.19, SD = 1.29, 51.8% male) with a diagnosed SRC seen at a concussion clinic. Participants were administered a computer-based version (COMP) of the PCSS followed by clinical open-ended symptom interview (OPEN) and clinician-guided PCSS (GUIDED). Participants' parents concurrently and independently endorsed their children's symptoms by completing the PCSS in the waiting room (PARENT). Total number of symptoms reported and total symptom severity score were analyzed and compared across the four PCSS administration methods. Results revealed significantly lower total number of symptoms for OPEN compared to GUIDED (p = .002), PARENT (p < .001), and COMP (p = .006); and significantly lower total severity score for OPEN compared to GUIDED (p = .04) and PARENT (p < .001). These data support using the PCSS as a structured method of assessing post-concussion symptoms and question the utility of unstructured interview methods for assessing symptoms in youth athletes with SRC.

Traumatic axonal injury and persistent emotional lability in an adolescent following moderate traumatic brain injury: A case study.

A 15-year-old male was treated secondary to sustaining a moderate traumatic brain injury (moderate TBI). Symptom self-report, and computerized and paper-and-pencil-based neurocognitive, vestibular/ocular motor, and imaging data were used throughout to document impairment and recovery. The patient demonstrated persistent emotional lability concurrent with vestibular impairment. In addition to clinical evaluation and management, the patient also underwent susceptibility-weighted imaging, which revealed axonal shearing across the corpus callosum and areas innervating the prefrontal cortex. Paper-and-pencil neurocognitive measures revealed persisting deficits, despite normal-appearing computerized test results. Implications of this case underline the importance of an integrative evaluation process including clinical interview, neurocognitive and vestibular/ocular physical therapy, and advanced neuroimaging, especially in cases with atypical presentation.

The management of sport-related concussion: considerations for male and female athletes.

Sport-related concussion continues to be a centerpiece of attention in the field of sports medicine. The benefit to using neurocognitive testing when managing concussion will be documented in this review. In addition to providing critical objective information on the neurocognitive status of the concussed athlete, research data will be provided on the pre- and post-concussion neurocognitive profiles of concussed male and female athletes. Specifically, an overview of research will be presented on the epidemiology of male and female concussion rates, as well as concussion outcomes including symptoms and cognitive function post-injury. Finally, a clinician's perspective on managing sports-related concussion will be presented focusing on three factors regarding sex differences: risk factors, clinical presentation, and management.

Incidence of sports-related concussion among youth football players aged 8-12 years.

OBJECTIVE: To determine the risk of concussion among youth football players (ages 8-12 years). STUDY DESIGN: Participants included 468 male youth football players in western Pennsylvania during the 2011 youth football season. Incidence rates (IRs) and incidence density ratios (IDRs) of concussion were calculated for games and practices and for age groups. RESULTS: There was a total of 11,338 (8415 practice and 2923 game) athletic exposures (AEs) in the study period, during which 20 medically diagnosed concussions occurred. A majority of concussions were the result of head-to-head (45%) contact. The combined concussion IR for practices and games was 1.76 per 1000 AEs (95% CI 0.99-2.54). The concussion IR was 0.24 per 1000 AEs (95% CI 0.04-0.79) in practices and 6.16 per 1000 AEs (95% CI 3.76-9.54) in games. The IDR for concussions in games to practices was 25.91 (95% CI 6.01-111.70). The IDR of concussions for youth aged 11-12 years compared with youth aged 8-10 years was 2.72 (95% CI 0.66-4.78). CONCLUSIONS: The overall IR for concussion in youth football players aged 8-12 years was comparable with that reported previously for high school and collegiate samples. However, participation in games was associated with an increase in risk of concussion compared with practices, which was higher than rates previously reported for high school and collegiate athletes. Younger players were slightly less likely to incur a concussion than were older players.