Introduction

Concussion, a form of mTBI (mild traumatic brain injury), is an issue of increasing importance in both professional and community sport contexts [1,2,3,4]. Research suggests concussion has historically been misunderstood and under-diagnosed [3, 5]. Due to recent increase in visibility of concussion testing in high-profile contact sports, there is increased awareness of concussion as an issue [1, 6]. Concussion is generally accepted to represent 70–90% of all TBI [7,8,9,10].

Sports-related concussion (SRC) represents up to 20% of these injuries [11,12,13]. Multiple studies speak to the correlation between contact sports and concussion, and there are increasing numbers of concussion cases presenting to medical settings [8, 9, 14,15,16]. Given this increase, it is pertinent to seek the perspectives of experts in the field on the current state of concussion knowledge and management.

Concussion incidence and prevalence numbers reflect the scope of the issue in the United States and New Zealand. As shown in Fig. 1, numbers have generally increased over the last 20 years. Raw data on paediatric concussion in NZ, both from hospital admissions and Accident Compensation Corporation (ACC) data, suggest upward trends, although in the period 2010–2019 overall concussion claims increased at a higher rate than SRC claims [Fig. 1., panel 1].Footnote 1, Footnote 2 Using ACC data, Quarrie et al. reported a mean incidence for male rugby players aged 0–20 of 12.06 per 1,000 players per year with concussion making up 3.1% of all injuries[16]. Gianotti & Hume noted wide incidence variety in previous rugby studies of 0.1–11.3 per 100 player season [17]. Concussion as a percentage of all injuries has been listed variously as 2.9% [18], 7.9% [19], and 18.4% [20].

Fig. 1
figure 1

Trends in concussion incidence in New Zealand and the United States

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In American studies reporting incidence data in high school (HS) athletes (per 10,000 athletic exposures (AE)) numbers varied from 0.8 to 6.6 (practice), 14.8 to 36.1 (competition), and 3.9 to 18.6 (overall) [13, 21,22,23,24,25,26,27]. The respective mean incidences from these studies were 3.8 practice, 22.3 game, and 9.5 overall. Therefore, according to these studies, gameplay was 5.9 times more likely than practice to result in concussion which grossly reflects the practice-game discrepancy across all HS sports. Of note more recent studies have had higher incidence rates [Fig. 1, panel 2].

Broadly this paper covered the time period 2000–2020 to give a finite definition to the data and to focus on the recent increase in concussion awareness. The aim of this study was to answer two questions: (1) How do current experts in the mTBI field (research, medical, sports coaching) see current trends in concussion awareness, assessment, management, and outcomes? (2) How do responses to these questions differ by country (US vs. NZ) and by discipline (research vs. sports coaching vs. sports medicine)?

Methods

Design

For this study a qualitative methodology was used to capture the depth of experts’ knowledge of concussion. Semi-structured interviews were used to provide a degree of standardization to the study, but also to provide sufficient scope for divergent responses.

Participants

There was one cohort of three (N = 3) participants in the US, and an additional cohort of three (N = 3) in NZ, equalling a total cohort of six (N = 6) participants. There was a total of two (N = 2) experts in each area: academic, medical, sports coaching/ training. There was one expert from each country in each area. The small cohort size was justified to allow for close analysis of the data.

Procedures

Interview questions were written and interviews arranged with participants. Interview questions were coded according to the expertise of the participant. Twelve (N = 12) questions were coded for all three experts (M = sports medicine physicians, R = researchers, T = trainers), the remaining questions (N = 13–17) were coded specifically for that expert or a combination of experts.

Semi-structured interviews were recorded electronically, via Zoom, using audio only. Verbatim transcripts were produced from the recordings using NVivo, a computer assisted qualitative data analysis software (CAQDAS). Transcripts were anonymized and read through by the researcher while listening to recordings to ensure accuracy from the originals.

Data analysis

Input from each expert was coded qualitatively, using the thematic analytic process described by Braun & Clarke and thematic comparison data described by Guest et al. [28, 29]. The analysis method used was inductive and iterative, and commonalities in codes were analysed via a thematic narrative analysis.

Initially, the transcripts were coded according to commonalities across the six interviews. This process of coding (writing one- or two-word summaries of each chunk of data) was completed for each interview, resulting in a long list of codes. As each new interview was coded, the original list of codes was re-analysed, in a process described by Corbin & Strauss as constant comparison [30].

The following stage involved narrowing down the existing long list of codes into overarching thematic categories as they appeared, such as symptoms, compliance, symptom resolution, and awareness. These codes were then used to label specific sections of the data using interview printouts, resulting in a narrowed-down list of fifteen (N = 15) themes.

Following the iterative process described by Corbin & Strauss the fifteen themes were narrowed down to three final categories (N = 3) [30]. This was done by creating a list of definitions for the concepts in the study, describing the themes using phrases or short sentences, again continually revisiting participant responses as new codes were developed, and attaching quotations from the transcripts which reflected these commonalities.

Reflecting the primary aim of the study, that of perspectives, final categories were reflective of participants’ subjective statements regarding experience and knowledge rather than objective data. As a result, three distinct categories emerged from the themes, which are described in Table 1: knowledge, management, and unanswered questions. Within each theme, commonalities between and across disciplines and between and across countries will be discussed based on relevance.

Table 1 Thematic analysis of transcribed interviews
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Results

Knowledge

In this series of questions, there was general agreement on improvement of concussion awareness. Regarding the role of media, participants agreed on its importance (especially in high profile sports) but that at times reporting is not accurate. Regarding definitions, participants generally agreed with NZ-R’s opposition to the use of the term ‘concussion.’ Regarding surveillance, participants agreed on its need but also its problematic nature. NZ participants (NZ-R, NZ-M, NZ-T) tended to express more confidence in national data. Trainer participants expressed more confidence in their school systems. Results are summarized In Table 2.

Table 2 Responses common to all participants, contrasted by country (NZ vs USA), contrasted by discipline (T vs. M vs. R): knowledge
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Management

Due to the open-ended nature of these semi-structured interviews, participants tended to have longer responses to the questions in this section. Participants agreed on the need for expert personnel to be involved and to be well trained, the importance of rapport with young athletes, the use of SCAT (Sports Concussion Assessment Tool) testing, the difficulty of baseline testing, that graduated RTP is more desirable than a blanket policy, and that compliance with RTP is improving. Contrasts between countries included US high school teams being more likely to have certified trainers on the side-line, the different tests used in each country, and the lower likelihood of US players to be RTP compliant if a big game is coming up. Contrasts between disciplines included R being less confident regarding the consistency of application of protocols, M emphasized the neuroplasticity of young brains while warning against confounding variables in baseline testing, while T underscored the importance of knowing their players (and downplaying the utility of standardized tests). Of note, US-M asserted concussion is now over-reported. Results are summarized in Table 3.

Table 3 Responses common to all participants, contrasted by country (NZ vs USA), contrasted by discipline (T vs. M vs. R): management
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Unanswered questions

Participants gave consistent responses regarding prevention, with all endorsing caution on issues of long-term damage (such as CTE) and second-impact syndrome. All participants agreed on the negligible evidence of protective equipment (headgear in rugby, helmets in football). Trainer responses differed slightly in this area. Both US-T and NZ-T stated the importance of safe tackling techniques. US-T also highlighted decreased contact in training, while NZ-T quoted NZ Rugby’s mandated age-based tackling guidelines. Results are summarized in Table 4.

Table 4 Responses common to all participants, contrasted by country (NZ vs USA), contrasted by discipline (T vs. M vs. R): unanswered questions
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Discussion

Knowledge

Participants agreed there has been an overall improvement in awareness of concussion in the public and the media, but that this level of knowledge is still limited. All participants agreed that the media has helped in this awareness, especially in higher profile professional sport, most often mentioned were rugby in NZ and football in the US. Particularly referring to the US, where due to its size, national awareness is at times lower, US-R stated the media has brought national attention to the issue, where it was lacking before. This was backed up by NZ-T who emphasized national awareness: “I'd have to probably take my hat off to the New Zealand Rugby Union with taking a really strong leadership role in that.”

Pertinent responses regarding concussion knowledge included US-T stating: “I don’t know if the media has quite the understanding that they should” and regarding the public stated, “people… correlate concussions to football and rugby or wrestling and head-to-head violent contact, when in actuality it doesn’t require any of that.” This was connected by participants to the issue of differing outcomes for children, with NZ-M asserting: “we should be more conservative with children” while also cautioning. “there is some evidence that young brains have the ability to recover better than old brains.” This was taken further by US-M: “you probably have a longer risk of problems from obesity… I’m kind of all about exercise and activity.”

These attitudes are reflected in recent literature by Field et al. who reported HS athletes may demonstrate slower recovery after concussion than college athletes [31]. McClincy et al. reported recovery from concussive injury may take longer in HS athletes than first thought [32]. Several studies stated that while a single concussion will likely have no long-term damage, multiple concussions may result in cumulative damage but the degree of this is unclear [33,34,35].

Challenges regarding concussion awareness is also reflected in the literature. Sye et al. conducted a NZ high school rugby player survey from 2000, which noted 50% have been told of concussion guidelines, 58% said the guidelines always applied, 60% identified the 3 week stand down rule, and 77% stated they should not return to play if still having symptoms. The authors reported concern that respondents also reported the false idea that you need to be “knocked out cold” (p. 1003) to have a concussion [6]. In a later NZ study little change was seen: 49.7% knew of concussion guidelines and 22% sought RTP advice from a physician [36].

Regarding current knowledge on prevention NZ-R, NZ-T, and US-T referred to national guidelines on tackling techniques and other strategies in junior rugby and junior American football [37, 38]. NZ-T in particular made multiple references to RugbySmart and the use of pocket concussion check cards used by coaches at the sideline [39]. National policy was less well reported in the US, US-T stated that regulations on safe tackling techniques are “a little bit of a grey area.” In NZ rugby, by contrast, all NZ participants reported the consistent use, at least in rugby, of mandated national guidelines for player participation and removal from play, including compulsory concussion education for coaches and referees. NZ-T also mentioned the policy of weight-restricted grades in NZ rugby, typically used up until the under-12 grade.

Such preventative measures, in conjunction with assessment tools, are mentioned frequently in the literature. In NZ, the national rugby body’s RugbySmart was cited by Gianotti et al. and side-line concussion check cards by Gianotti and Hume [17, 39]. In NZ rugby-related concussion claims fell 10.7% after implementation of education programs [36]. In the US, the CDC’s HEADS UP programme is mentioned frequently [40,41,42,43]. In an analysis of data from the programme (2016–2017), Sarmiento et al. concluded the trends in assessment are consistent with a similar study from 2014 with most coaches having access to relevant educational material but overall access remaining limited [42].

Although objective data were usually not provided by participants there was general agreement that concussion or mTBI constitutes a majority of all TBI (“at least 80%” according to US-R) and that concussion becomes far more prevalent at adolescence: “from about the age of 10, the primary mechanism from that point is contact sport” (US-R). US-M and NZ-M said the “vast majority” of the concussion they see are in contact or collision sport. Both trainers (US-T, NZ-T) reported that contact in training has generally decreased, with more emphasis on other activities, such as aerobic exercise and weight training.

The more objective data provided by the literature generally reflects these viewpoints. Children tend to be over-represented in concussion numbers: under 18 years were more likely to have head injuries and concussions than adults [44], concussions had highest rate in 18–20 age group [16], and 61% of concussions occurred in children [45]. These numbers are significant as, with the emphasis on this study on contact sport, adolescents participate in sports more than adults, and generally concussion occurs at a higher rate in HS sports vs adult sports [12].

Management

Physician and trainer participants heavily emphasized the importance of rapport building and knowing their athletes/patients, often valuing this above standardized testing. NZ-T stated: “[the coaches] build really close relationships with these kids… You can have all the tests in the world, but they’re gonna know… if that young person is unwell.” Researcher participants were more likely to value objective data, but also acknowledged the expertise of side-line personnel. US-R stated: “athletic trainers, I think, have a very high knowledge of concussion.”

All participants mentioned some variation of the SCAT in assessing concussion in this population [46]. US-M and US-T frequently referenced the Balance Error Scoring System (BESS) [47] and ImPACT testing [48], but acknowledged this is more often used at college (university) level, and is less often used at high school level due to cost. US-R referenced the CDC’s ACE (Acute Concussion Evaluation) test [49]. NZ-M and NZ-T referenced the King–Devick test [50]. Multiple studies speak to the validity of these tests [51,52,53,54,55].

All participants agreed on the need for removal from play and some form of graduated RTP in the event of a concussion occurring. US-M summed this up by stating “if I think he has a concussion, he's not playing right now.” NZ-R and NZ-M suggested in NZ rugby medical clearance from a physician is needed to return to play, but NZ-T stated it is not needed “if they have stuck to the protocols.” In the US this appears to be less mandated, but US-T did state medical clearance for RTP is required in his job.

A graduated rather than rigid stand down policy was generally favoured. NZ-R voiced some dissent on this issue, stating the justification for graduated RTP is “pretty arbitrary” and needs to be researched more. US-M emphasized the importance of keeping athletes involved, “if they no longer have any kind of leadership or involvement, I think that's a whole other problem. Therefore, we try to get them back fairly quickly.” This is backed up by a recent study by Yang et al. who found that self-paced physical and cognitive activity when recovering from concussion was neither helpful nor damaging to the child [56].

Physician and trainer participants had a more optimistic view of compliance than much of the literature suggests. Studies have listed barriers, including lack of quality education, lack of buy-in due to pre-conceived ideas, and lack of time for educational meetings. Lowrey & Morain reported “little to no formal enforcement mechanisms to ensure compliance” (p. 294) at the youth sports level due to barriers of provider access, parent cooperation, and awareness [57]. Haarbauer-Krupa et al. reported compliance was higher for athletes with recurrent concussion, concussions from collision sports, and when a physician makes the RTP decision [23], but conversely Kelly and Erdal reported athletes and those with history of concussion were more likely to underestimate RTP [58]. Multiple studies on rugby reported poor compliance. Kearney and See described only 12% compliance with RTP guidelines, Sye et al. stated the majority of participants (154/220, 70%) made RTP decision themselves, while Orr and Cheng reported all players with suspected concussion were allowed to play in the next match [6, 59, 60].

Questions on the level of reporting produced unanimous agreement that concussion was under-reported 20 years ago, but dissent from US-M and NZ-T as to whether it is still under-reported. Whereas NZ-R (“I believe that it is still underreported. In addition, it was definitely underreported 20 years ago”) and US-R (“I think it's underreported, but not to the same degree as it was in 2000”) reflected roughly the same trend, US-M asserted it is now over-reported: “you're not going to hear that from too many people… I think at the high school level, it's probably overdone.” NZ-T associated greater reporting to improved knowledge: “Twenty years ago… I think people had a lack of understanding of what concussion was and the ramifications of it.”

While participants tended to express confidence in the reporting systems used within their facilities, studies usually quote surveillance conducted on a more macro scale. Bell et al. summarized the challenges of surveillance as follows: ICD-9 codes have limited sensitivity, other factors are not considered, outpatient data for those who did not seek medical care are excluded, and concussions may be missed [61]. Limitations in ACC data were summarized by Quarrie et al. who asserted “[the] rate of concussion claims made to the ACC almost certainly reflects only a small subset of the number of concussions players sustain.” (p. 425) [16].

Unanswered questions

All participants mentioned long-term outcomes and follow-up as key areas of future research. Part of this was based on a lack of clarity regarding such issues as second-impact syndrome. All participants stated the rarity of second-impact syndrome, but US-T and NZ-M both gave examples of cases of deaths, where it was suspected, with US-T describing it as “my biggest concern.” All participants agreed that the science needs to be clearer on this. US-R stated, “even without having second-impact syndrome, individuals can persist with their concussion symptoms if they have more than one [concussion] or if they have one during their recovery,” while US-M commented “I think there's a whole controversy with second impact syndrome. It's really extraordinarily rare. I think probably what you're dealing with is just another very severe head injury in the second instance.”

Reference to second-impact syndrome is most relevant to the US. The most concrete narrative of concussion legislation had its genesis in the Children’s Health Act (2000) which led to HEADS UP and ACE [62]. In 2009, the case of Zackery Lystedt, a young man who was concussed in a HS football game in Washington, returned to the game, and later died, resulted in all fifty states passing concussion laws by 2014 [57, 63, 64]. Despite this, some American studies suggested roles of parents and athletes are still unclear and actual application of concussion regulations are more up to the sporting bodies themselves [4, 11, 65].

Concussion prevention was the final area discussed. All participants agreed that such factors as limiting contact training and safer tackling techniques, especially for children learning the game, were vital (US-M: “I mean, kids were taught for a long time: stick your helmet on them on their chest. That's what they were taught. Well, that's a way to get yourself a broken neck or a concussion”) and there was agreement that the data on protective equipment is less clear. Both trainer participants (US-T, NZ-T) greatly emphasized the importance of technique, NZ-T: “massive focus around technique… tackling, cleaning out… how to fall, how to hold your body when you go into contact, all those kinds of things.” The research participants (NZ-R, US-R) stated what would help improve research of long-term outcomes would be improved surveillance, preferably on a national level.

The general trend of research similarly suggests there is varying evidence to suggest protective equipment specifically prevents concussion or the severity of concussion. Recent reviews quote significant decrease in concussion risk when wearing football helmets in both field and lab studies [66, 67]. However, rugby studies suggest little or no evidence protective equipment, such as headgear, prevents concussion [68, 69]. There is stronger data suggested by other factors: decline in tackle football and contact limitations [43] and correlation between decrease in injury claims and education on safe tackling, rucking, and scrummaging techniques in rugby [39].

Questions on research directions were addressed by the research (US-R, NZ-R) and medical (US-M, NZ-M) participants. Researchers tended to state the importance of defining and measuring concussion incidence in original research. All four participants (research and medical) agreed on the need for more research, in such areas as long-term outcomes, cohort studies, and the use of control groups. US participants agreed more national surveillance data is needed, while NZ participants suggested ACC data is valid, but its specificity could be improved.

Limitations

This study was subject to several limitations. Although every effort was made to be accurate in transcription minor errors may have been present. Given the international nature of the study, there may have been minor cultural or linguistic discrepancies in responses to questions vis-à-vis the wording of certain questions. There was a small sample size of participants (N = 6); therefore, results are not able to be generalized to the wider population. The expertise of the medical (US-M, UZ-M) and trainer participants (US-T, NZ-T) was limited to sports medicine and football/rugby, respectively, meaning the wider context of paediatric mTBI was missed. Moreover, due to these participants having most experience in contact sport and concussion, this study did not address mechanism of injury, did not address mTBI in the younger (under 10) population, and did not consider wider factors, such as gender, socioeconomics, and cultural diversity.

Conclusions

Concussion experts agree on many areas; however, divergent opinions were apparent. Findings showed general commonalities on the importance of concussion education, the improvement of concussion awareness, compliance to concussion protocols, and the need to research long-term outcomes. Fewer commonalities were found regarding the level of concussion reporting, the impact of multiple concussions, whether paediatric and adult concussion should be treated similarly, and the utility of concussion tests.