Investigating the Range of Symptom Endorsement at Initiation of a Graduated Return-to-Play Protocol After Concussion and Duration of the Protocol: A Study From the National Collegiate Athletic Association-Department of Defense Concussion, Assessment, Research, and Education (CARE) Consortium

The association between Guardian Cap use during practices and sport-related concussion risk in high school American football players

OBJECTIVE

Guardian Caps (GCs) have been widely implemented at all levels of American football participation based on laboratory evidence that they may reduce head impact forces. The purpose of this study was to determine if GC use during practice was associated with a lower risk of sport-related concussion (SRC) during practices and games among high school football players.

METHODS

Data were collected on 2610 athletes from 41 Wisconsin schools that self-selected into GC or Non-GC cohorts. Athletic trainers recorded practice and game exposures and SRCs through the 2023 season. Generalised linear mixed models were built to determine the effect of GC utilisation on SRC rates, accounting for school and player exposures.

RESULTS

In the total cohort (Non-GC n=1188 (45.5%); GC n=1422 (54.5%)), 180 athletes (6.9%) sustained SRCs. 64 SRCs occurred during practice (GC n=33 (51.6%); Non-GC n=31 (48.4%)). GC use was not associated with a decreased risk of SRC during practice in the univariable analysis (relative risk (RR)=1.04, 95% CI 0.58 to 1.86, p=0.90) or after accounting for previous SRC within the last year (RR 1.01, 95% CI 0.57 to 1.79, p=0.97). No players of either cohort wore GCs during games. There were 116 SRCs sustained during games (GC n=68 (58.6%); Non-GC n=48 (41.4%)). GC use during practice was not associated with the risk of SRC during games in the univariable analysis (RR 1.13, 95% CI 0.72 to 1.78, p=0.60) or after accounting for previous SRC within the last year (RR 1.13, 95% CI 0.71 to 1.78, p=0.61).

CONCLUSION

GC use during practice in high school American football players was not associated with a decreased risk of sustaining SRC in practice or games.

Association of Alzheimer's Disease Polygenic Risk Score with Concussion Severity and Recovery Metrics

BACKGROUND

Identification of genetic alleles associated with both Alzheimer's disease (AD) and concussion severity/recovery could help explain the association between concussion and elevated dementia risk. However, there has been little investigation into whether AD risk genes associate with concussion severity/recovery, and the limited findings are mixed.

OBJECTIVE

We used AD polygenic risk scores (PRS) and APOE genotypes to investigate any such associations in the NCAA-DoD Grand Alliance CARE Consortium (CARE) dataset.

METHODS

We assessed six concussion outcomes in 931 participants, including two recovery measures (number of days to asymptomatic and to return to play (RTP)) and four severity measures (scores on SAC and BESS, SCAT symptom severity and total number of symptoms). We calculated the PRS using a published score and performed multiple linear regression to assess the relationship of the PRS with outcomes. We also used ANOVAs, t-tests, and chi-square tests to examine outcomes by APOE genotype.

RESULTS

Higher PRS was associated with longer injury to RTP time in the normal RTP (< 24 days) subgroup (p = 0.024). A one standard deviation increase in the PRS resulted in a 9.89 hour increase to RTP time. This result was no longer significant after inclusion of covariates. There were no other consistently significant effects.

CONCLUSIONS

Our findings suggest high AD genetic risk is not associated with more severe concussions or poor recovery in young adults. Future studies should attempt to replicate these findings in larger samples with longer follow-up using PRS calculated from diverse populations.

Is It All in Your Head? Placebo Effects in Concussion Prevention

Sports-related concussions (SRCs) are a major health issue in athletes of varying ages, ability levels, and sports. Concerns over the short- and long-term consequences of SRCs have incentivized a wealth of products and policies aimed at reducing SRC risk. Research suggesting the effectiveness of such interventions at reducing SRCs has facilitated their adoption by sports organizations and, in some cases, product commercialization. However, the body of SRC mitigation research is almost entirely devoid of placebo or sham groups, which raises important questions about the true clinical effectiveness of these interventions. This Current Opinion explores the plausibility of placebo effects within the scope of SRC prevention, describes why the lack of placebo/sham groups in the current body of literature is problematic, and provides recommendations for including placebo/sham groups in future SRC research.

Quantitative Pupillometry Predicts Return to Play and Tracks the Clinical Evolution of Mild Traumatic Brain Injury in US Military Academy Cadets: A Military Traumatic Brain Injury Initiative Study

BACKGROUND AND OBJECTIVES

The objective of this study was to determine the utility of the pupillary light reflex use as a biomarker of mild traumatic brain injury (mTBI).

METHODS

This prospective cohort study was conducted at The US Military Academy at West Point. Cadets underwent a standard battery of tests including Balance Error Scoring System, Sports Concussion Assessment Tool Fifth Edition Symptom Survey, Standard Assessment of Concussion, and measure of pupillary responses. Cadets who sustained an mTBI during training events or sports were evaluated with the same battery of tests and pupillometry within 48 hours of the injury (T1), at the initiation of a graded return to activity protocol (T2), and at unrestricted return to activity (T3).

RESULTS

Pupillary light reflex metrics were obtained in 1300 cadets at baseline. During the study period, 68 cadets sustained mTBIs. At T1 (<48 hours), cadets manifested significant postconcussion symptoms (Sports Concussion Assessment Tool Fifth Edition P < .001), and they had decreased cognitive performance (Standardized Assessment of Concussion P < .001) and higher balance error scores (Balance Error Scoring System P < .001) in comparison with their baseline assessment (T0). The clinical parameters showed normalization at time points T2 and T3. The pupillary responses demonstrated a pattern of significant change that returned to normal for several measures, including the difference between the constricted and initial pupillary diameter (T1 P < .001, T2 P < .05), dilation velocity (T1 P < .01, T2 P < .001), and percent of pupillary constriction (T1 P < .05). In addition, a combination of dilation velocity and maximum constriction velocity demonstrates moderate prediction ability regarding who can return to duty before or after 21 days (area under the curve = 0.71, 95% CI [0.56-0.86]).

CONCLUSION

This study's findings indicate that quantitative pupillometry has the potential to assist with injury identification and prediction of symptom severity and duration.

Association of Sport Helmet Status on Concussion Presentation and Recovery in Male Collegiate Student-Athletes

Sporting helmets contain force attenuating materials which reduce traumatic head injury risk and may influence sport-related concussion (SRC) sequelae. The purpose of this study was to examine the association of sport helmet status with SRC-clinical presentation and recovery trajectories in men's collegiate athletes. Sport helmet status was based on the nature of sports being either helmeted/non-helmeted. 1070 SRCs in helmeted (HELM) sports (Men's-Football, Ice Hockey, and Lacrosse), and 399 SRCs in non-helmeted (NOHELM) sports (Men's-Basketball, Cheerleading, Cross Country/Track & Field, Diving, Gymnastics, Soccer, Swimming, Tennis, and Volleyball) were analyzed. Multivariable negative binomial regression models analyzed associations between sport helmet status and post-injury cognition, balance, and symptom severity, adjusting for covariate effects (SRC history, loss of consciousness, anterograde/retrograde amnesia, event type). Kaplan-Meier curves evaluated median days to: initiation of return to play (iRTP) protocol, and unrestricted RTP (URTP) by sport helmet status. Log-rank tests were used to evaluate differential iRTP/URTP between groups. Two independent multivariable Weibull accelerated failure time models were used to examine differential iRTP and URTP between groups, after adjusting for aforementioned covariates and symptom severity score. Overall, the median days to iRTP and URTP was 6.3 and 12.0, respectively, and was comparable across NOHELM- and HELM-SRCs. Post-injury symptom severity was lower (Score Ratio 0.90, 95%CI 0.82, 0.98), and cognitive test performance was higher (Score Ratio 1.03, 95%CI 1.02, 1.05) in NOHELM-compared to HELM-SRCs. Estimated time spent recovering to iRTP/URTP was comparable between sport helmet status groups. Findings suggest that the grouping of sports into helmeted and non-helmeted show slight differences in clinical presentation but not recovery.

Missing School Days Following Sport-Related Concussion in High School Athletes

Importance

Sport-related concussions (SRC) can significantly impact students' attendance and academic performance, highlighting the importance of gradual return-to-learn protocols for recovery. Understanding the association between missed school days and recovery, especially across genders, is vital for effective concussion management in high school athletes.

Objectives

To describe missed school days in high school athletes with SRC and to determine associations between missed school days and authorized clearance to return to competition; secondarily, to determine whether school days missed differed by gender.

Design, Setting, and Participants

Cohort study among student athletes participating in athletics sponsored by the Michigan High School Athletic Association (MHSAA) during academic years 2015 to 2023. SRC was a participant eligibility criterion and was defined as a head injury during participation in a MHSAA-sanctioned event. Data were analyzed from August 2015 to June 2023.

Exposures

Primary exposure was missed school days; additional exposures included gender, year of season, concussion history, event type, sport level, contact level, and athletic trainer involvement.

Main Outcome and Measure

The primary outcome was time to full unrestricted clearance following SRC.

Results

The analysis included a total of 20 934 individuals with SRC (13 869 boys [66.25%]). Gender (χ23 = 167.40; P < .001), season (χ221 = 57.41; P < .001), event type (χ23 = 99.29; P < .001), sport level (χ29 = 68.15; P < .001), contact level (χ26 = 56.73; P < .001), and initial evaluation (χ23 = 147.13; P < .001) were independently associated with missed school days. Athletes took a median (IQR) of 11 (7-16) days to return to full unrestricted clearance. Relative to no missed school days, there was a significant mean increase of 57% (incidence rate ratio, 1.57; 95% CI, 1.52-1.62) in time to full unrestricted clearance for 3 or more missed school days. The estimated mean days to return to sport were 12.15 (95% CI, 12.00-12.30) for 0 missed school days, 12.68 (95% CI, 12.39-12.96) for 1 missed school day, 15.47 (95% CI, 15.06-15.87) for 2 missed school days, and 19.08 (95% CI, 18.55-19.62) for 3 or more missed school days.

Conclusions and Relevance

This cohort study found that high school athletes typically missed 2 or fewer school days after SRC, suggesting that concussion management teams adhered to current recommendations of 24 to 48 hours of initial rest. The dose association, with more missed school days associated with slower return to play, suggests athletes' missing more school days (eg, ≥3) may be associated with severity of concussion and warrant additional support to return to school and/or sport.

Sport-Specific Recovery Trajectories for NCAA Collegiate Athletes Following Concussion

The recovery trajectories of collegiate athletes with sport-related concussion (SRC) are well characterized in contact/collision sports but are less well understood in limited contact sports with lower risk, reducing the ability of clinicians to effectively manage the return-to-play (RTP) process. The current study investigated the time to asymptomatic and RTP across a broad range of male and female collegiate sports and sought to group sports by recovery intervals. Data from the Concussion Assessment, Research and Education (CARE) Consortium included 1049 collegiate athletes who sustained a SRC while participating in game or practice/training of their primary sport. Injury setting and subsequent clinical presentation data were obtained. Survival analysis using the Cox Proportional Hazard model estimated the median recovery times for each sport. Optimal univariate K-means clustering grouped sports into recovery categories. Across all sports, median time to asymptomatic following SRC ranged from 5.9 (female basketball) to 8.6 days (male wrestling). Median RTP protocol duration ranged from 4.9 days (female volleyball) to 6.3 days (male wrestling). Median total RTP days ranged from 11.2 days (female lacrosse) to 16.9 days (male wrestling). Sport clusters based on recovery differences in time to asymptomatic (3) and RTP protocol duration (2) were identified. The findings from this study of a large sample of more than 1000 NCAA collegiate athletes with SRC show there exists ranges in recovery trajectories. Clinicians can thus manage athletes with similar guidelines, with individualized treatment and recovery plans.

Where is the research on sport-related concussion in Olympic athletes? A descriptive report and assessment of the impact of access to multidisciplinary care on recovery

OBJECTIVES

This cohort study reported descriptive statistics in athletes engaged in Summer and Winter Olympic sports who sustained a sport-related concussion (SRC) and assessed the impact of access to multidisciplinary care and injury modifiers on recovery.

METHODS

133 athletes formed two subgroups treated in a Canadian sport institute medical clinic: earlier (≤7 days) and late (≥8 days) access. Descriptive sample characteristics were reported and unrestricted return to sport (RTS) was evaluated based on access groups as well as injury modifiers. Correlations were assessed between time to RTS, history of concussions, the number of specialist consults and initial symptoms.

RESULTS

160 SRC (median age 19.1 years; female=86 (54%); male=74 (46%)) were observed with a median (IQR) RTS duration of 34.0 (21.0-63.0) days. Median days to care access was different in the early (1; nSRC=77) and late (20; nSRC=83) groups, resulting in median (IQR) RTS duration of 26.0 (17.0-38.5) and 45.0 (27.5-84.5) days, respectively (p<0.001). Initial symptoms displayed a meaningful correlation with prognosis in this study (p<0.05), and female athletes (52 days (95% CI 42 to 101)) had longer recovery trajectories than male athletes (39 days (95% CI 31 to 65)) in the late access group (p<0.05).

CONCLUSIONS

Olympic athletes in this cohort experienced an RTS time frame of about a month, partly due to limited access to multidisciplinary care and resources. Earlier access to care shortened the RTS delay. Greater initial symptoms and female sex in the late access group were meaningful modifiers of a longer RTS.

Associations of Sex and Sport Contact-Level with Recovery Timelines Among Collegiate Athletes with Sport-Related Concussion

BACKGROUND

Growing interest has motivated recent studies to examine differences in recovery after sport-related concussion (SRC) by sex. However, heterogeneity in study design, participants, and recovery outcomes has led to mixed findings. Further work is needed to evaluate potential differences by sex and to investigate the role of related characteristics, such as sport contact-level, in recovery timelines. This study aimed to investigate whether concussion recovery trajectories differ by sex, considering a priori clinical and demographic covariates, and accounting for the sequence of recovery outcomes. Our secondary question was whether sport contact-level modifies the relationship between sex and time to outcomes. Using data from the Ivy League-Big Ten Epidemiology of Concussion Study, we included SRCs reported across five academic years; 2015-2020 (February 2020). We used Cox proportional hazards regressions to estimate associations between sex and time from injury to three outcomes: (1) symptom resolution, (2) return to academics, (3) return to full play, accounting for measured confounders.

RESULTS

Among 1160 SRCs (male, n = 667; female, n = 493) with complete data, median age overall was 20 years (25th-75th percentiles:19-21), and most occurred among athletes playing high-contact sports (78.0%). Males were slightly more likely to complete symptom resolution over time compared to females (HR = 1.18, 95%CI = 1.05-1.33), but results were attenuated in fully adjusted models (HR 1.13, 95%CI = 0.99-1.29). Similarly, the HR of full academic return for males compared to females was 1.22 (95%CI = 1.07-1.38), but was attenuated in fully adjusted models (HR = 1.11, 95%CI = 0.97-1.28). The HR of full return to play for males compared to females was 1.14 (95%CI = 1.02-1.28), and was attenuated after adjustment (HR = 1.06, 95%CI = 0.93-1.20) as well. The interaction between sex and playing a high/low-contact sport was not statistically significant across models, though differences were apparent.

CONCLUSIONS

Among a cohort of collegiate athletes with SRC, recovery timelines appeared similar between male and female athletes, adjusting for measured confounders. Differences by sex, considering sport contact-level, were evident and may be important clinically and in future studies. This study used robust methods, accounting for nesting in the sequence of RTP outcomes. Results inform concussion management protocols and planned qualitative work to further elucidate how collegiate athletes experience concussion recovery.

KEY POINTS

Heterogeneity in study design, participants, and recovery outcomes has led to mixed findings in determining differences in recovery trajectories after concussion by sex. We found that having longer time to symptom resolution, and also the sequence of having academic return before symptoms resolve and longer time to academic return were confounders in the relationship between sex and RTP timelines. Time to sequential recovery outcomes appeared similar between male and female athletes, adjusting for observable confounders. Further differences by sex were evident when considering contact-level, and may be important to consider clinically and in future research. Results indicate that differences in concussion recovery trajectories by sex may be largely attributed to and driven by differences in sports with a men's or women's team only, such as football, and this should be explored further.

Association of Alzheimer's disease polygenic risk score with concussion severity and recovery metrics

Identification of genetic alleles associated with both Alzheimer's disease (AD) and concussion severity/recovery could help explain the association between concussion and elevated dementia risk. However, there has been little investigation into whether AD risk genes associate with concussion severity/recovery, and the limited findings are mixed. We used AD polygenic risk scores (PRS) and APOE genotypes to investigate any such associations in the NCAA-DoD Grand Alliance CARE Consortium (CARE) dataset. We assessed six outcomes in 931 total participants. The outcomes were two concussion recovery measures (number of days to asymptomatic status, number of days to return to play (RTP)) and four concussion severity measures (scores on SAC and BESS, SCAT symptom severity, and total number of symptoms). We calculated PRS using a published score [1] and performed multiple linear regression (MLR) to assess the relationship of PRS with the outcomes. We also used t-tests and chi-square tests to examine outcomes by APOE genotype, and MLR to analyze outcomes in European and African genetic ancestry subgroups. Higher PRS was associated with longer injury to RTP in the normal RTP (<24 days) subgroup ( p = 0.024), and one standard deviation increase in PRS resulted in a 9.89 hour increase to the RTP interval. There were no other consistently significant effects, suggesting that high AD genetic risk is not strongly associated with more severe concussions or poor recovery in young adults. Future studies should attempt to replicate these findings in larger samples with longer follow-up using PRS calculated from diverse populations.

The Role of Level of Play in Concussions in High School Athletes

OBJECTIVES

To examine level of play (LOP) as a risk factor for concussion severity and recovery-related outcomes among high school athletes, stratified by sex, and among boys, by sport (football, non-football male sports).

DESIGN/SETTING

Secondary analysis of data collected through the High School Reporting Information Online surveillance system for academic years 2007-2008 through 2018-2019.

PARTICIPANTS

A total of 9916 concussions were reported between the academic years 2007-2008 and 2018-2019 from 9 sports (5189 from football; 2096 from non-football male sports; 2631 from female sports).

MAIN OUTCOME MEASURE

Examined the association between LOP (Freshman, Junior Varsity [JV], and Varsity teams) and concussion outcomes (number of concussion symptoms, symptom resolution time [SRT], and time to return to play [RTP]).

RESULTS

Compared with Varsity football athletes, concussed JV football athletes had on average 0.19 fewer concussion symptoms, longer SRT (>1 week vs <1 week: odds ratio [OR] = 1.3; 95% confidence interval [CI], 1.1-1.5), and longer RTP (1-3 weeks vs <1 week: OR = 1.5; 95% CI, 1.2-1.9; >3 weeks vs <1 week: OR = 1.6; 95% CI, 1.1-2.3). Compared with Varsity football athletes, Freshman football athletes had on average 0.48 fewer concussion symptoms, longer SRT (OR = 1.3; 95% CI, 1.1-1.5), and longer RTP (1-3 weeks vs <1 week: OR = 1.5; 95% CI, 1.1-2.0; >3 weeks vs <1 week: OR = 2.0; 95% CI, 1.3-3.0). Similarly, compared with female athletes on Varsity teams, concussed JV female athletes had longer RTP (1-3 weeks vs <1 week: OR = 1.8; 95% CI, 1.2-2.7). Trend analyses revealed an increase in the number of concussion symptoms between 2015-2016 and 2018-2019, a decrease between 2009-2010 and 2018-2019 for SRT of less than 1 week, and an increase between 2014-2015 and 2018-2019 for RTP of less than 1 week among Varsity football athletes. Among Varsity female athletes, there was a linear decrease during the study period for RTP of less than 1 week.

CONCLUSIONS

Despite a higher number of symptoms overall and in recent years, Varsity football players had shorter RTP than Freshman and JV athletes.

Association Between Symptom Cluster Endorsement at Initiation of a Graduated Return-to-Activity Protocol and Time to Return to Unrestricted Activity After Concussion in United States Service Academy Cadets

BACKGROUND

The endorsement of symptoms upon initiation of a graduated return-to-activity (GRTA) protocol has been associated with prolonged protocols. It is unclear whether there are specific symptom clusters affecting protocol durations.

PURPOSE

To describe the endorsement of specific concussion symptom clusters at GRTA protocol initiation and examine the association between symptom cluster endorsement and GRTA protocol duration.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

This study was conducted among cadets enrolled at 3 US service academies. Participants completed an evaluation upon GRTA protocol initiation. Participants endorsing symptoms were binarized based on 6 symptom clusters (cognitive, emotional, insomnia, physical, sensitivity, and ungrouped). The primary outcome of interest was GRTA protocol duration based on symptom cluster endorsement severity. Prevalence rates were calculated to describe symptom cluster endorsement. Kaplan-Meier survival estimates and univariate and multivariable Cox proportional hazards regression models were calculated for all 6 symptom clusters to estimate GRTA protocol duration while controlling for significant covariates.

RESULTS

Data from 961 concussed participants were analyzed. Of these, 636 participants were asymptomatic upon GRTA protocol initiation. Among the 325 symptomatic participants, the physical symptom cluster (80%) was most endorsed, followed by the cognitive (29%), insomnia (23%), ungrouped (19%), sensitivity (15%), and emotional (9%) clusters. Univariate results revealed a significant association between endorsing cognitive (hazard ratio [HR], 0.79; p = .001), physical (HR, 0.84; p < .001), insomnia (HR, 0.83; p = .013), sensitivity (HR, 0.70; p < .001), and ungrouped (HR, 0.75; p = .005) symptom clusters and GRTA protocol duration. Endorsing physical (HR, 0.84; p < .001) and sensitivity (HR, 0.81; p = .036) clusters maintained a significant association with GRTA protocol duration in the multivariable models.

CONCLUSION

Participants endorsing physical or sensitivity symptom clusters displayed GRTA protocols prolonged by 16% to 19% compared with participants not endorsing that respective cluster after controlling for significant covariates.

Temporal Network Analysis of Neurocognitive Functioning and Psychological Symptoms in Collegiate Athletes After Concussion

Sport-related concussion (SRC) is associated with several post-injury consequences, including neurocognitive decrements and psychological distress. Yet, how these clinical markers interact with each other, the magnitude of their interrelationships, and how they may vary over time following SRC are not well understood. Network analysis has been proposed as a statistical and psychometric method to conceptualize and map the complex interplay of interactions between observed variables (e.g., neurocognitive functioning and psychological symptoms). For each collegiate athlete with SRC (n = 565), we constructed a temporal network as a weighted graph, with nodes, edges, and the set of weights associated with each edge at three time-points (baseline, 24-48 h post-injury, and asymptomatic), that graphically depicts the interrelated nature of neurocognitive functioning and symptoms of psychological distress throughout the recovery process. This graph shows that the inter-group relationships between neurocognitive functioning and symptoms of psychological distress were stronger at the 24-48 h time-point than at baseline or at the asymptomatic time-point. Further, all symptoms of psychological distress and neurocognitive functioning significantly improved from the 24-48 h time-point to asymptomatic status. The effect sizes of these changes ranged from 0.126 (small) to 0.616 (medium). This research suggests that significant improvements in symptoms of psychological distress appear necessary to drive related improvements in neurocognitive functioning and vice versa. Therefore, clinical interventions should consider the importance of managing psychological distress during the acute care of individuals with SRC to help ameliorate negative outcomes.

Clinical recovery from concussion-return to school and sport: a systematic review and meta-analysis

OBJECTIVE

To define the time frames, measures used and modifying factors influencing recovery, return to school/learn (RTL) and return to sport (RTS) after sport-related concussion (SRC).

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

8 databases searched through 22 March 2022.

ELIGIBILITY CRITERIA

Studies with diagnosed/suspected SRC and interventions facilitating RTL/RTS or investigating the time and modifying factors for clinical recovery. Outcomes included days until symptom free, days until RTL and days until RTS. We documented study design, population, methodology and results. Risk of bias was evaluated using a modified Scottish Intercollegiate Guidelines Network tool.

RESULTS

278 studies were included (80.6% cohort studies and 92.8% from North America). 7.9% were considered high-quality studies, while 23.0% were considered high risk of bias and inadmissible. The mean days until symptom free was 14.0 days (95% CI: 12.7, 15.4; I²=98.0%). The mean days until RTL was 8.3 (95% CI: 5.6, 11.1; I²=99.3%), with 93% of athletes having a full RTL by 10 days without new academic support. The mean days until RTS was 19.8 days (95% CI: 18.8, 20.7; I²=99.3%), with high heterogeneity between studies. Several measures define and track recovery, with initial symptom burden remaining the strongest predictor of longer days until RTS. Continuing to play and delayed access to healthcare providers were associated with longer recovery. Premorbid and postmorbid factors (eg, depression/anxiety, migraine history) may modify recovery time frames. Though point estimates suggest that female sex or younger age cohorts take longer to recover, the heterogeneity of study designs, outcomes and overlap in CIs with male sex or older age cohorts suggests that all have similar recovery patterns.

CONCLUSION

Most athletes have full RTL by 10 days but take twice as long for an RTS.

PROSPERO REGISTRATION NUMBER

CRD42020159928.

Functional Outcomes, Injury Variables, and Athlete Characteristics Associated with Post-Concussion Sleep Disturbance

OBJECTIVE

To examine the relationship between sleep disturbance and functional outcomes following a concussion. Also, to explore athlete and injury-related variables that may be related to risk factors for poor sleep following concussion.

METHOD

124 collegiate athletes completed a neuropsychological evaluation within 14 days of sustaining a sport-related concussion (SRC). Athletes were categorized as sleep disturbed (n = 52) or not sleep disturbed (n = 72). Outcome variables included symptom reports, cognitive performance (mean performance and variability), and mood (depression). Injury characteristics and athlete characteristics explored were loss of consciousness (LOC) associated with the injury, whether the athlete was immediately removed from play, and history of prior concussions.

RESULTS

Sleep disturbed athletes reported more symptoms, F(4, 119) = 7.82, p < 0.001, ƞ2 = 0.21, were more likely to be symptomatic at the time of testing, χ2(1, N = 124) = 19.79, p < 0.001, φ = 0.40, and were marginally more likely to experience clinically significant depression, χ2(1, N = 120) = 3.03, p = 0.08, φ = 0.16, than not sleep disturbed athletes. There were no cognitive differences between the groups, p > 0.05. A greater proportion of sleep disturbed athletes experienced LOC (30%) compared to not sleep disturbed athletes (13%), χ2(1, N = 118) = 4.99, p = 0.03, φ = -0.21.

CONCLUSION

Sleep disturbances following SRC are associated with a broad range of self-reported symptoms. LOC may be associated with an increased risk of developing sleep disturbances; alternatively, sleep disturbances may increase the risk of LOC following concussion.

Association Between Symptom Burden at Initiation of a Graduated Return to Activity Protocol and Time to Return to Unrestricted Activity After Concussion in Service Academy Cadets

BACKGROUND

Current consensus and position statements recommend that concussed patients be asymptomatic upon the initiation of the graduated return to activity (RTA) protocol. However, a significant number of concussed patients are beginning their RTA protocols while endorsing symptoms.

PURPOSE

To characterize symptom endorsement at the beginning of the RTA protocol and examine the association between symptom endorsement and RTA protocol duration in service academy cadets.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A prospective cohort study was conducted with cadets at 3 US service academies. Postconcussion symptom inventories were recorded upon the initiation of an RTA protocol. The Sport Concussion Assessment Tool Symptom Inventory was used to classify participants into 3 groups (0 symptoms, 1 symptom, and ≥2 symptoms) upon the initiation of the RTA protocol. The primary outcome of interest was RTA protocol duration. Kaplan-Meier survival estimates were calculated to estimate RTA protocol duration by symptom endorsement, sex, varsity status, academic break, and time to graduated RTA initiation. Univariate and multivariable Cox proportional hazards models were used to estimate the association between symptom endorsement at the initiation of the RTA protocol and RTA protocol duration (α < .05).

RESULTS

Data were analyzed from 966 concussed cadets (36% women). Headache (42%) and faintness/dizziness (44%) were the most commonly endorsed symptoms on the Sport Concussion Assessment Tool-Third Edition and the Brief Symptom Inventory-18, respectively. Univariate results revealed a significant association between endorsing ≥2 symptoms and RTA protocol duration. In the multivariable model, endorsing ≥2 symptoms maintained a statistically significant association with RTA protocol duration. Significant associations were observed between RTA protocol duration and nonvarsity status (27% longer), women (15% longer), academic breaks (70% longer), and time to the initiation of the RTA protocol (1.1% longer daily incremental increase) after controlling for covariates.

CONCLUSION

Symptom endorsement at the initiation of an RTA protocol was associated with RTA protocol duration. Cadets who had returned to preinjury baseline symptom burden or improved from baseline symptom burden and endorsed ≥2 symptoms at the initiation of the RTA protocol took longer to RTA.

Greater Acute Concussion Symptoms Are Associated With Longer Recovery Times in NCAA Division III Collegiate Athletes

We examined the association between the severity of acute concussion symptoms and time to return to school and to sports in National Collegiate Athletic Association (NCAA) Division III collegiate athletes. We hypothesized that students with the lowest burden of acute symptoms, measured in the first 72 h, would have the fastest return to school and sports and those with the highest burden of symptoms would have the slowest return to school and sports. This injury surveillance cohort included 808 athletes from 11 NCAA Division III colleges who sustained a concussion between 2014 and 2019. Athletic trainers documented time to return to school and to sports. Kruskal-Wallis tests with post-hoc planned comparison Mann-Whitney U tests were used to assess whether athletes took longer to return based on their acute symptom burden (Low, Medium, or High). Survival analysis (Kaplan Meier with log rank tests) was used to compare the recovery times based on acute symptom burden (censored at 28 days). Chi-square tests compared the proportion of those who had not yet returned to school or sports at various recovery benchmarks (i.e., 1 week, 10 days, 2 weeks, 3 weeks, 4 weeks) based on acute symptom burden. Women (median = 5 days) took slightly longer than men (median = 4 days) to return to school (p = 0.001; r = −0.11, small effect). Women and men did not differ on time to return to sports (p = 0.32, r = −0.04). A greater proportion with high acute symptoms remained out of school at 5 (odds ratio, OR = 4.53), 7 (OR = 4.98), and 10 (OR = 4.80) days compared to those with low acute symptoms. A greater proportion with high acute symptoms remained out of sports at 10 (OR = 4.11), 14 (OR = 3.46), and 21 (OR = 3.01) days compared to those with low acute symptoms. This study shows a strong association between having a high burden of acute post-concussion symptoms and having a slower return to school and sports in Division III collegiate athletes. Moreover, it also illustrates the converse: that those athletes with a low burden of acute symptoms have a faster return to school and sports.

Acute Physical and Mental Activity Influence on Concussion Recovery

INTRODUCTION

Physical activity (PA) and mental activity (MA) postconcussion has received renewed attention to improve concussion management; however, most protocols start after several days and do not assess the acute window. Therefore, the purpose of this study was to assess PA and MA in the first 48 h postconcussion on the time to symptom-free status and return to play.

METHODS

We recruited 78 NCAA Division I athletes (male, 51.3%; age, 19.6 ± 1.4 yr; height, 173.7 ± 11.5 cm; weight, 80.1 ± 23.2 kg) who were diagnosed with a sports-related concussion. Participants completed a 0-5 PA and MA scale daily until fully cleared for return to participation (mean, 15.1 ± 6.9 d). A quadratic model regression assessed PA and MA over the first 2 d (acute) postconcussion on to time to symptom-free status and return to play.

RESULTS

The overall model was significant for both time to symptom free (r2 = 0.27, P = 0.004) and return to play (r2 = 0.23, P = 0.019). Reported PA was the only significant predictor for time to symptom-free (P = 0.002) and return-to-participation (P = 0.006) day. Reported MA was not associated either outcome.

CONCLUSIONS

The primary finding of this study was that mild to moderate PA acutely postconcussion was associated with reduced time to symptom free and return to participation as opposed to either lower or higher levels of PA. Conversely, acute MA was not associated with recovery outcomes. These results further elucidate the role of postconcussion PA.

In-Season Concussion Symptom Reporting in Male and Female Collegiate Rugby Athletes

Symptom inventories are generally only collected after a suspected concussion, but regular in-season monitoring may allude to clinical symptoms associated with repetitive subconcussive impacts and potential undiagnosed concussions. Despite sex-specific differences in symptom presentation and outcome of concussion, no return-to-play protocol takes sex into account. The objective of this study was to monitor a cohort of contact-sport athletes and compare the frequency and severity of in-season concussion-like symptom reporting between sexes. Graded symptom checklists from 144 female and 104 male athlete-seasons were administered weekly to quantify the effect of subconcussive impacts on frequency and severity of in-season symptom reporting. In-season, mean symptom severity score (SSS) (p = 0.026, mean difference of 1.8), mean number of symptoms (p = 0.044, mean difference of 0.9), max SSS (p < 0.001, mean difference of 19.2), and max number of symptoms (p < 0.001, mean difference of 6.8) were higher in the females. The females' survey results showed differences between elevated and concussed SSS (p < 0.005, mean difference of 28.1) and number of symptoms reported (p = 0.001, mean difference of 6.6). The males did not have a difference in SSS (p = 0.97, mean difference of 1.12) nor in number of symptoms (p = 0.35, mean difference of 1.96) from elevated to concussed athletes. Rugby players report concussion-like symptoms in the absence of a diagnosed concussion in-season. Female athletes reported elevated symptom frequencies with greater severities than the males, but both sexes reported considerable levels throughout the season.

Impairments in Dynamic Postural Control across Concussion Clinical Milestones

The aim of this study was to assess gait initiation (GI) performance longitudinally across clinical concussion recovery milestones through return to participation (RTP). We recruited 54 collegiate student-athletes, 27 with concussions and 27 matched controls (15 female and 12 male per group). Participants performed five trials of GI at baseline and again at five post-concussion clinical milestones: 1) Acute, the day clinical tests achieved baseline values on the 2) Balance Error Scoring System (BESS), 3) Immediate Post-Concussion Assessment and Cognitive Test ImPACT, 4) Asymptomatic, and 5) RTP Day. GI performance on six outcome measures (anterior/posterior and medial/lateral center of pressure displacements and velocities during the anticipatory postural adjustment [APA] phase and initial step length and velocity) with repeated-measures mixed model and pair-wise post hoc. A reliable change index (RCI) was calculated, and post-concussion participant's performance was compared to the RCI at milestones. There were significant interactions for APA posterior and lateral displacement, APA posterior velocity, step length, and step velocity. The post-hoc tests identified significant deficits across clinical milestones and at RTP for APA posterior and lateral displacement, step length, and step velocity. There were no post-hoc differences for any outcome measure in the control group. At RTP, 85.2-88.9% of concussion participants had at least one outcome measure which exceeded the 80% or 95% RCI. The primary finding of this study was persistent impairments in dynamic postural control, suggesting ongoing neurophysiological impairment despite clinical recovery. These results suggest that collegiate student-athletes may be RTP before neurophysiological recovery and potentially exposing themselves to elevated risk of recurrent concussion or subsequent musculoskeletal injury.

Bifactor Model of the Sport Concussion Assessment Tool Symptom Checklist: Replication and Invariance Across Time in the CARE Consortium Sample

BACKGROUND

Identifying separate dimensions of concussion symptoms may inform a precision medicine approach to treatment. It was previously reported that a bifactor model identified distinct acute postconcussion symptom dimensions.

PURPOSE

To replicate previous findings of a bifactor structure of concussion symptoms in the Concussion Assessment Research and Education (CARE) Consortium sample, examine measurement invariance from pre- to postinjury, and evaluate whether factors are associated with other clinical and biomarker measures.

STUDY DESIGN

Cohort study (Diagnosis); Level of evidence, 2.

METHODS

Collegiate athletes were prospectively evaluated using the Sport Concussion Assessment Tool-3 (SCAT-3) during preseason (N = 31,557); 2789 were followed at <6 hours and 24 to 48 hours after concussion. Item-level SCAT-3 ratings were analyzed using exploratory and confirmatory factor analyses. Bifactor and higher-order models were compared for their fit and interpretability. Measurement invariance tested the stability of the identified factor structure across time. The association between factors and criterion measures (clinical and blood-based markers of concussion severity, symptom duration) was evaluated.

RESULTS

The optimal structure for each time point was a 7-factor bifactor model: a General factor, on which all items loaded, and 6 specific factors-Vestibulo-ocular, Headache, Sensory, Fatigue, Cognitive, and Emotional. The model manifested strict invariance across the 2 postinjury time points but only configural invariance from baseline to postinjury. From <6 to 24-48 hours, some dimensions increased in severity (Sensory, Fatigue, Emotional), while others decreased (General, Headache, Vestibulo-ocular). The factors correlated with differing clinical and biomarker criterion measures and showed differing patterns of association with symptom duration at different time points.

CONCLUSION

Bifactor modeling supported the predominant unidimensionality of concussion symptoms while revealing multidimensional properties, including a large dominant General factor and 6 independent factors: Headache, Vestibulo-ocular, Sensory, Cognitive, Fatigue, and Emotional. Unlike the widely used SCAT-3 symptom severity score, which declines gradually after injury, the bifactor model revealed separable symptom dimensions that have distinct trajectories in the acute postinjury period and different patterns of association with other markers of injury severity and outcome.

CLINICAL RELEVANCE

The SCAT-3 total score remains a valuable, robust index of overall concussion symptom severity, and the specific factors identified may inform management strategies. Because some symptom dimensions continue to worsen in the first 24 to 48 hours after injury (ie, Sensory, Fatigue, Emotional), routine follow-up in this time frame may be valuable to ensure that symptoms are managed effectively.

Quality of life of ice hockey players after retirement due to concussions

Background:

Sports-related concussion (SRC) is increasingly recognized as a potential health problem in ice hockey. Quality of life (QoL) in players retiring due to SRC has not been thoroughly addressed.

Materials & methods:

QoL using the Sports Concussion Assessment Tool 5th Edition, Impact of Event Scale-Revised and Short Form Health Survey was measured in Swedish ice hockey players who retired due to persistence of postconcussion symptoms or fear of attaining additional SRC.

Results:

A total of 76 players were assessed, on average of 5 years after their most recent SRC. Overall, retired players had a high burden of postconcussion symptoms and reduced QoL.

Conclusion:

Retired concussed ice hockey players have a reduced QoL, particularly those retiring due to postconcussion symptoms. Symptom burden should be continuously evaluated and guide the decision to retire.

Concussions sustained while playing ice hockey are increasingly recognized as a potential health problem. Long-term consequences for players retiring due to concussions have not been fully investigated. Therefore, we evaluated symptoms, quality of life and post-traumatic stress in former Swedish ice hockey players who retired due to postconcussion symptoms or to a fear of attaining additional concussions. We found that retired ice hockey players with a history of concussions had a low quality of life and high post-traumatic stress, particularly in players with a high symptom burden. We recommend that symptom burden should be continuously evaluated and guide the decision to retire.