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ObjectivesTo evaluate prevention strategies, their unintended consequences and modifiable risk factors for sport-related concussion (SRC) and/or head impact risk.DesignThis systematic review and meta-analysis was registered on PROSPERO (CRD42019152982) and conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.Data sourcesEight databases (MEDLINE, CINAHL, APA PsycINFO, Cochrane (Systematic Review and Controlled Trails Registry), SPORTDiscus, EMBASE, ERIC0 were searched in October 2019 and updated in March 2022, and references searched from any identified systematic review.Eligibility criteriaStudy inclusion criteria were as follows: (1) original data human research studies, (2) investigated SRC or head impacts, (3) evaluated an SRC prevention intervention, unintended consequence or modifiable risk factor, (4) participants competing in any sport, (5) analytic study design, (6) systematic reviews and meta-analyses were included to identify original data manuscripts in reference search and (7) peer-reviewed. Exclusion criteria were as follows: (1) review articles, pre-experimental, ecological, case series or case studies and (2) not written in English.ResultsIn total, 220 studies were eligible for inclusion and 192 studies were included in the results based on methodological criteria as assessed through the Scottish Intercollegiate Guidelines Network high (‘++’) or acceptable (‘+’) quality. Evidence was available examining protective gear (eg, helmets, headgear, mouthguards) (n=39), policy and rule changes (n=38), training strategies (n=34), SRC management strategies (n=12), unintended consequences (n=5) and modifiable risk factors (n=64). Meta-analyses demonstrated a protective effect of mouthguards in collision sports (incidence rate ratio, IRR 0.74; 95% CI 0.64 to 0.89). Policy disallowing bodychecking in child and adolescent ice hockey was associated with a 58% lower concussion rate compared with bodychecking leagues (IRR 0.42; 95% CI 0.33 to 0.53), and evidence supports no unintended injury consequences of policy disallowing bodychecking. In American football, strategies limiting contact in practices were associated with a 64% lower practice-related concussion rate (IRR 0.36; 95% CI 0.16 to 0.80). Some evidence also supports up to 60% lower concussion rates with implementation of a neuromuscular training warm-up programme in rugby. More research examining potentially modifiable risk factors (eg, neck strength, optimal tackle technique) are needed to inform concussion prevention strategies.ConclusionsPolicy and rule modifications, personal protective equipment, and neuromuscular training strategies may help to prevent SRC.PROSPERO registration numberCRD42019152982.

BackgroundConcussion is the most common injury in youth ice hockey. Whether mouthguard use lowers the odds of concussion remains an unanswered question.ObjectiveTo determine the association between concussion and mouthguard use in youth ice hockey.MethodsNested case–control design. Cases and controls were identified from two prospective cohort studies using valid injury surveillance methods. Cases were players concussed during a game or practice; controls were players who sustained a non-concussion injury during a game or practice. The primary exposure was mouthguard use at time of injury; mouthguard type (dental custom fit or off the shelf) was a secondary exposure. Physician-diagnosed or therapist-suspected concussion was the primary outcome. Dental injury was a secondary outcome. Multilevel logistic regression with random effect at a team level was used to obtain ORs for the mouthguard effect, adjusted for level of play, age group, position, concussion history, mechanism of injury, cohort, session type and body checking policy.ResultsAmong cases, 236/315 (75%) were wearing a mouthguard at time of injury, while 224/270 (83%) controls were wearing a mouthguard at time of injury. Any mouthguard use was associated with an adjusted OR for concussion of 0.36 (95% CI 0.17 to 0.73). Off-the-shelf mouthguards were associated with a 69% lower odds of concussion (adjusted OR: 0.31; 95% CI 0.14 to 0.65). Dental custom-fit mouthguards were associated with a non-significant 49% lower odds of concussion (adjusted OR: 0.51; 95% CI 0.22 to 1.10). No dental injuries were identified in either cohort.ConclusionMouthguard use was associated with lower odds of concussion. Players should be required to wear mouthguards in youth ice hockey.

ObjectiveTo 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).DesignSystematic review and meta-analysis.Data sources8 databases searched through 22 March 2022.Eligibility criteriaStudies 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.Results278 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.ConclusionMost athletes have full RTL by 10 days but take twice as long for an RTS.PROSPERO registration numberCRD42020159928.

To compare the incidence rates and odds of concussion between youth ice hockey players based on mouthguard use and helmet age. Within a 5-year longitudinal cohort (2013/2014 to 2017/2018) of male and female ice hockey players (ages 11-18; n=3330 players) in Alberta (Canada), we analysed the relationship of equipment and concussion in both a prospective cohort and nested case (concussion) control (acute musculoskeletal injury) approach. The prospective cohort included baseline assessments documenting reported mouthguard use (yes/sometimes, no use), helmet age (newer/<2 years old, older/≥2 years old) and important covariables (weight, level of play, position of play, concussion history, body checking policy), with weekly player participation throughout the season. The nested case-control component used injury reports to document equipment (mouthguard use, helmet age) and other information (eg, mechanism and type of injury) for the injury event. Multivariable mixed effects negative binomial regression (prospective cohort, incidence rate ratios (IRRs)) and multivariable mixed effects logistic regression (nested case-control, odds ratios (OR)) examined the association between equipment and concussion. Players who reported wearing a mouthguard had a 28% lower concussion rate (IRR=0.72, 95% CI 0.56 to 0.93) and 57% lower odds of concussion (OR=0.43, 95% CI 0.27 to 0.70) compared with non-wearers. There were no associations in the concussion rate (IRR=0.94, 95% CI 0.75 to 1.15) and odds (OR=1.16, 95% CI 0.73 to 1.86) between newer and older helmets. Wearing a mouthguard was associated with a lower concussion rate and odds. Policy mandating use should be considered in youth ice hockey. More research is needed to identify other helmet characteristics (eg, quality, fit) that could lower concussion risk.

ObjectivesTo systematically review the scientific literature regarding the acute assessment of sport-related concussion (SRC) and provide recommendations for improving the Sport Concussion Assessment Tool (SCAT6).Data sourcesSystematic searches of seven databases from 2001 to 2022 using key words and controlled vocabulary relevant to concussion, sports, SCAT, and acute evaluation.Eligibility criteria(1) Original research articles, cohort studies, case–control studies, and case series with a sample of >10; (2) ≥80% SRC; and (3) studies using a screening tool/technology to assess SRC acutely (<7 days), and/or studies containing psychometric/normative data for common tools used to assess SRC.Data extractionSeparate reviews were conducted involving six subdomains: Cognition, Balance/Postural Stability, Oculomotor/Cervical/Vestibular, Emerging Technologies, and Neurological Examination/Autonomic Dysfunction. Paediatric/Child studies were included in each subdomain. Risk of Bias and study quality were rated by coauthors using a modified SIGN (Scottish Intercollegiate Guidelines Network) tool.ResultsOut of 12 192 articles screened, 612 were included (189 normative data and 423 SRC assessment studies). Of these, 183 focused on cognition, 126 balance/postural stability, 76 oculomotor/cervical/vestibular, 142 emerging technologies, 13 neurological examination/autonomic dysfunction, and 23 paediatric/child SCAT. The SCAT discriminates between concussed and non-concussed athletes within 72 hours of injury with diminishing utility up to 7 days post injury. Ceiling effects were apparent on the 5-word list learning and concentration subtests. More challenging tests, including the 10-word list, were recommended. Test–retest data revealed limitations in temporal stability. Studies primarily originated in North America with scant data on children.ConclusionSupport exists for using the SCAT within the acute phase of injury. Maximal utility occurs within the first 72 hours and then diminishes up to 7 days after injury. The SCAT has limited utility as a return to play tool beyond 7 days. Empirical data are limited in pre-adolescents, women, sport type, geographical and culturally diverse populations and para athletes.PROSPERO registration numberCRD42020154787.

ObjectivesTo compare the incidence rates and odds of concussion between youth ice hockey players based on mouthguard use and helmet age.Materials and methodsWithin a 5-year longitudinal cohort (2013/2014 to 2017/2018) of male and female ice hockey players (ages 11–18; n=3330 players) in Alberta (Canada), we analysed the relationship of equipment and concussion in both a prospective cohort and nested case (concussion) control (acute musculoskeletal injury) approach. The prospective cohort included baseline assessments documenting reported mouthguard use (yes/sometimes, no use), helmet age (newer/<2 years old, older/≥2 years old) and important covariables (weight, level of play, position of play, concussion history, body checking policy), with weekly player participation throughout the season. The nested case–control component used injury reports to document equipment (mouthguard use, helmet age) and other information (eg, mechanism and type of injury) for the injury event. Multivariable mixed effects negative binomial regression (prospective cohort, incidence rate ratios (IRRs)) and multivariable mixed effects logistic regression (nested case–control, odds ratios (OR)) examined the association between equipment and concussion.ResultsPlayers who reported wearing a mouthguard had a 28% lower concussion rate (IRR=0.72, 95% CI 0.56 to 0.93) and 57% lower odds of concussion (OR=0.43, 95% CI 0.27 to 0.70) compared with non-wearers. There were no associations in the concussion rate (IRR=0.95, 95% CI 0.77 to 1.18) and odds (OR=1.16, 95% CI 0.73 to 1.86) between newer and older helmets.ConclusionsWearing a mouthguard was associated with a lower concussion rate and odds. Policy mandating use should be considered in youth ice hockey. More research is needed to identify other helmet characteristics (eg, quality, fit) that could lower concussion risk.

ObjectiveTo compare rates of injury and concussion among non-elite (lowest 60% by division of play) Bantam (ages 13–14 years) ice hockey leagues that disallow body checking to non-elite Bantam leagues that allow body checking.MethodsIn this 2-year cohort study, Bantam non-elite ice hockey players were recruited from leagues where policy allowed body checking in games (Calgary/Edmonton 2014–2015, Edmonton 2015–2016) and where policy disallowed body checking (Kelowna/Vancouver 2014–2015, Calgary 2015–2016). All ice hockey game-related injuries resulting in medical attention, inability to complete a session and/or time loss from hockey were identified using valid injury surveillance methodology. Any player suspected of having concussion was referred to a study physician for diagnosis and management.Results49 body checking (608 players) and 33 non-body checking teams (396 players) participated. There were 129 injuries (incidence rate (IR)=5.52/1000 hours) and 54 concussions (IR=2.31/1000 hours) in the body checking teams in games. After policy change, there were 31 injuries (IR=2.50/1000 hours) and 17 concussions (IR=1.37/1000 hours) in games. Policy disallowing body checking was associated with a lower rate of all injury (adjusted incidence rate ratio (IRR)=0.45; 95% CI: 0.27 to 0.76). The point estimate showed a lower rate of concussion (adjusted IRR=0.59; 95% CI: 0.30 to 1.17), but this was not statistically significant.ConclusionPolicy change disallowing body checking in non-elite Bantam ice hockey resulted in a 55% lower rate of injury. There is growing evidence that disallowing body checking in youth ice hockey is associated with fewer injuries.

ObjectivesTo compare rates of injury and concussion among U-15 (ages 13–14 years) ice hockey players playing in leagues allowing body checking, but who have a varying number of years of body checking experience.MethodsThis 5-year longitudinal cohort included U-15 ice hockey players playing in leagues where policy allowed body checking. Years of body checking experience were classified based on national/local body checking policy. All ice hockey game-related injuries were identified using a validated injury surveillance methodology. Players with a suspected concussion were referred to a study sport medicine physician. Multiple multilevel Poisson regression analysis was performed, adjusting for important covariates and a random effect at a team level (offset by game exposure hours), to estimate injury and concussion incidence rate ratios (IRRs).ResultsIn total, 1647 players participated, contributing 1842 player-seasons (195 players participating in two seasons). Relative to no body checking experience, no significant differences were found in the adjusted IRRs for game-related injury for players with 1 year (IRR=0.94; 95% CI: 0.69 to 1.28) or 2+ years (IRR=0.89; 95% CI: 0.56 to 1.40) body checking experience. No differences were found in the rates of concussion for players with 1 year (IRR=0.79; 95% CI: 0.51 to 1.22) but was significantly lower for players with 2+ years (IRR=0.51; 95% CI: 0.28 to 0.94) compared with no body checking experience.ConclusionsAmong ice hockey players aged 13–14 years participating in leagues permitting body checking, the adjusted rates of all injury were not significantly different between those that had body checking experience and those that did not. While the rates of concussion were significantly lower among those with 2+ years of body checking experience, the number of concussions potentially prevented in U-15 does not offset the number of concussions prevented through policy disallowing body checking at U-13.

ObjectivesThe objective of this study is to evaluate the effect of policy change disallowing body checking in adolescent ice hockey leagues (ages 15–17) on reducing rates of injury and concussion.MethodsThis is a prospective cohort study. Players 15–17 years-old were recruited from teams in non-elite divisions of play (lower 40%–70% by division of play depending on year and city of play in leagues where policy permits or prohibit body checking in Alberta and British Columbia, Canada (2015–18). A validated injury surveillance methodology supported baseline, exposure-hours and injury data collection. Any player with a suspected concussion was referred to a study physician. Primary outcomes include game-related injuries, game-related injuries (>7 days time loss), game-related concussions and game-related concussions (>10 days time loss).Results44 teams (453 player-seasons) from non-body checking and 52 teams (674 player-seasons) from body checking leagues participated. In body checking leagues there were 213 injuries (69 concussions) and in non-body checking leagues 40 injuries (18 concussions) during games. Based on multiple multilevel mixed-effects Poisson regression analyses, policy prohibiting body checking was associated with a lower rate of injury (incidence rate ratio (IRR): 0.33 (95% CI 0.21 to 0.51)) and concussion (IRR: 0.41; 95% CI 0.23 to 0.73. This translates to an absolute rate reduction of 5.51 injuries/1000 game-hours (95% CI 3.21 to 7.81) and the prevention of 8770 injuries (95% CI 5111 to 12429) in Canada annually.ConclusionsThe rate of injury was 70% lower (concussion 57% lower) in leagues not permitting body checking in non-elite 15–17 years old leagues highlighting the potential public health impact of policy prohibiting body checking in older adolescent ice hockey players.

Mechanical chest compression devices have the potential to help maintain high-quality cardiopulmonary resuscitation (CPR), but despite their increasing use, little evidence exists for their effectiveness. We aimed to study whether the introduction of LUCAS-2 mechanical CPR into front-line emergency response vehicles would improve survival from out-of-hospital cardiac arrest. The pre-hospital randomised assessment of a mechanical compression device in cardiac arrest (PARAMEDIC) trial was a pragmatic, cluster-randomised open-label trial including adults with non-traumatic, out-of-hospital cardiac arrest from four UK Ambulance Services (West Midlands, North East England, Wales, South Central). 91 urban and semi-urban ambulance stations were selected for participation. Clusters were ambulance service vehicles, which were randomly assigned (1:2) to LUCAS-2 or manual CPR. Patients received LUCAS-2 mechanical chest compression or manual chest compressions according to the first trial vehicle to arrive on scene. The primary outcome was survival at 30 days following cardiac arrest and was analysed by intention to treat. Ambulance dispatch staff and those collecting the primary outcome were masked to treatment allocation. Masking of the ambulance staff who delivered the interventions and reported initial response to treatment was not possible. The study is registered with Current Controlled Trials, number ISRCTN08233942. We enrolled 4471 eligible patients (1652 assigned to the LUCAS-2 group, 2819 assigned to the control group) between April 15, 2010 and June 10, 2013. 985 (60%) patients in the LUCAS-2 group received mechanical chest compression, and 11 (<1%) patients in the control group received LUCAS-2. In the intention-to-treat analysis, 30 day survival was similar in the LUCAS-2 group (104 [6%] of 1652 patients) and in the manual CPR group (193 [7%] of 2819 patients; adjusted odds ratio [OR] 0·86, 95% CI 0·64–1·15). No serious adverse events were noted. Seven clinical adverse events were reported in the LUCAS-2 group (three patients with chest bruising, two with chest lacerations, and two with blood in mouth). 15 device incidents occurred during operational use. No adverse or serious adverse events were reported in the manual group. We noted no evidence of improvement in 30 day survival with LUCAS-2 compared with manual compressions. On the basis of ours and other recent randomised trials, widespread adoption of mechanical CPR devices for routine use does not improve survival. National Institute for Health Research HTA – 07/37/69.