Sports injury surveillance, coding and classification systems

High quality data are needed about sports injury occurrence and the risk/protective factors associated with its aetiology. This depends on robust methods to monitor injury incidence and to collect relevant exposure (ie, sports participation) with standardised definitions so that results can be compared and contrasted spatially (across regions and sports) and temporally (over time). Together with clinical colleagues, the ACRISP epidemiologists and biostatisticians are advancing the design of, and reporting from, sports injury surveillance systems; contributing to international efforts to improve the coding/classification of sports injuries; informing international consensus statements for sports injury surveillance; and providing guidance on the appropriate statistical analysis of injury data. The two ACRISP research papers in this issue of BJSM IPHP are key recent outputs from this work until now.1 ,2

The first paper from the ACRISP team in the current BJSM issue presents the Subsequent Injury Classification (SIC) model developed to categorise multiple, recurrent, exacerbation or new injuries in the context of acute and overuse injuries that makes provision for all potential within-person correlations.1 Correct categorisation of subsequent injury of any type requires the input of significant clinical expertise, and the SIC model combines this expertise with more objective statistical criteria. This new way of classifying subsequent injuries includes, for the first time, explicit consideration of the possible relationships (correlations) between different injuries within an injured person. It has already started to be used with success by other groups, as shown by recent abstracts from the 2014 IOC Injury Prevention Conference in Monaco3 ,4 and its inclusion in the new international Athletics injury definition consensus statement.5

The second paper from ACRISP in this issue gives an overview of the statistical issues that need to be considered when analysing subsequent injury data.2 The paper compares different types of survival analysis models for subsequent event data through their application to prospectively collected professional rugby league injury data over one season. It shows how such models can be applied and explains why current common methods of analysis are inadequate for subsequent sports injury data.2 Extension of this modelling approach to risk factor identification has been published elsewhere.6

Ongoing sports injury prevention research will be hampered if there is little application of the more sophisticated statistical models for modelling subsequent injury data. Moreover, predictive or causal models to underpin sports-related musculoskeletal injury prevention strategies will be incorrect if they continue to ignore the inherent relationships between injuries or apply inadequate analysis methods. These two papers from ACRISP now set the basis and direction for future research in this important area.

Prospective monitoring of sports injury incidence and injury causation

Sports injury studies need to incorporate injury experiences over more than one season if they are to describe the incidence of subsequent injury accurately, as well as to document any non-acute adverse impacts they might have on health status, future injury risk and ongoing participation in sport. ACRISP's research is contributing to the design, validation and analysis of data from large-scale cohort studies to monitor injury experiences (including recurrences), the impacts of these injuries and sports participation on health (eg, need for joint replacement or reconstruction surgery, development of osteoarthritis, impact of overuse injuries, etc) and future sport participation (eg, time away from sport due to injury1 ,2 ,7). Further, its research combines these prospective studies with fundamental mechanistic and biomechanical studies to better understand the aetiology of injury and identification of suitable prevention measures. For example, ACRISP's research is contributing to improved diagnostic tools for tendinopathy,8 and is also shaping clinical management and research into tendinopathy9 and related musculoskeletal disorders.10 Other research is providing new understanding into the biomechanics of injuries,11 such as concussion and shoulder injury, is a prerequisite for developing effective equipment and methods to assess the equipment performance.12 ,13

Intervention effectiveness, implementation, dissemination and sustainability

Implementation research within community sport is critical because, even if interventions have been shown to be efficacious in controlled trials, if they cannot also be demonstrated to be widely adopted and sustained, then it is unlikely that they will have any preventive effect. There is very little information about how to translate research evidence into effective sports injury interventions and how to implement interventions in sport successfully.14 ACRISP's research is leading international efforts to contribute new insights into the sports delivery settings and individual behaviour contexts in which interventions are to be implemented.15 ,16 Our research has involved detailed investigations into the organisational, policy and individual behavioural barriers and enablers of evidence-based sports injury prevention interventions in sports settings.17 ,18 Major work over the past 5 years has been the development, implementation and evaluation of the FootyFirst lower limb injury prevention programme and delivery plan for Australian Football nationally.19 ,20 ACRISP's impact biomechanics research is showing how enhanced knowledge can lead to improved equipment standards, which are an important mechanism for translating the science of injury prevention into products bought off the shelf.21 ,22

Concussion and injury in youth ice hockey

Ice hockey is one of Canada's most popular sports with >25% of male youth participating. It is also one of the highest injury producing sports in youth. Concussion has been a matter of increasing concern in leagues where body checking is permitted.23–25 SIPRC's most significant research contributions are highlighted by a 10-year programme of research in youth ice hockey that has informed policy change. Research findings demonstrated that policy allowing body checking in Pee Wee ice hockey (ages 11–12) leads to a 3–4-fold greater risk of injury and concussion compared to leagues where body checking is not allowed.26 Further, body checking experience at younger ages does not decrease the risk of all injury and concussion in older (ages 13–14) players.27 This landmark research programme evaluating body checking policy and risk factors for injury and concussion in youth ice hockey has led initially to provincial (2011) and subsequently to national policy change delaying body checking in youth ice hockey from age 11 to 13 in the USA (2011) and then in Canada (2013). This policy change has had a large public health impact in reducing the burden of concussion and injury in youth ice hockey. Elimination of body checking in 11–12-year-old leagues is expected to translate to over 1300 injuries prevented in the province of Alberta annually (400 concussions). The estimated direct medical cost savings nationally exceed $C 2,000 000 annually in this age group alone. Further research will inform future policy change in older age groups (ages 13–17) in non-elite levels of play. Programmatic research evaluating concussion prevention and management strategies in youth sport is a key SIPRC priority. The youth ice hockey research programme also includes examination of preseason evaluation tools in youth ice hockey players (eg, neurocognitive, clinical, functional, sport-specific performance and neuroimaging) in the identification of risk factors for concussion and predictors of longer term sequelae following concussion.28–32 The SIPRC team has evaluated the efficacy of vestibular and cervical physiotherapy following concussion that has informed concussion management practice.33

Injury prevention to prevent osteoarthritis

The efficacy of the neuromuscular training injury prevention programme has consistently demonstrated a reduction in the risk of youth soccer and basketball injuries by more than 30%.34 ,35 Ongoing collaborations with several national and international research groups will focus on the development and evaluation of such programmes in other youth community sports (eg, rugby and football). The development and evaluation of a physical education curriculum-based high-intensity neuromuscular training prevention strategy suggests a reduction in sport and recreational injury risk by >50% as well as a reduction in adiposity in junior high school students (ages 11–15).36 Behaviour change and long-term maintenance of such programmes are an ongoing focus of inquiry. Based on previous youth RCTs and cohort studies (n>8000), SIPRC has developed a unique longitudinal cohort examining the long-term consequences of joint injury in youth, including post-traumatic osteoarthritis (PTOA).37 Outcomes include physical activity participation, adiposity, functional outcomes, biomechanics, biomarkers and MRI hypothesised to be associated with PTOA in young people with a history of knee injury. This research will inform the development of secondary prevention strategies to delay the onset and progression of PTOA. In partnership with community stakeholders (Alberta Health Services Strategic Clinical Network and Bone and Joint Canada), SIPRC researchers are leading the development of provincial and national strategies in the prevention of injury and PTOA.

The burden of illness and injury in specific populations of athletes

The group developed a web-based electronic injury and illness surveillance programme (WEB-IISS), which was based on the studies the group conducted together with FIFA–Medical Assessment Research Center (F-MARC) during the 2009 Confederations Cup football tournament,38 and the 2010 FIFA World Cup in South Africa.39 As part of these early studies, an illness surveillance system was developed and this provided novel data on illness in football players. The full WEB-IISS, including illness and injury surveillance, was then applied during the 2012 London Paralympic Games,40–42 and again in the 2014 Sochi Winter Paralympic Games. These studies were conducted in collaboration with the IPC medical committee. The novel data derived from these studies now form the basis of an ongoing longitudinal injury and illness surveillance programme in athletes with disabilities—an area that has received very little attention in the sport and exercise medicine literature until now. Several illness and injury prevention strategies can now be identified and their impact can be assessed in future studies.

This group also developed a similar electronic illness and injury surveillance system for team sports participating in tournaments.43 Illness data during a 16-week rugby union tournament showed a high incidence of illness during international travel.44 These data have a much wider application for athletes from other sports codes that travel across multiple time zones to compete in international tournaments. Once again, these baseline data now form the basis for implementing prevention strategies to reduce the burden of illness resulting from international travel. Similarly, data reported in this edition indicates a high risk of injury during the 16-week rugby union tournament.45 Once again, injury prevention strategies can now be introduced and the impact of these can be evaluated in future studies.

Protection of the health of the athlete participating in mass community-based endurance sports events

It is well recognised that physical activity is an important component of a healthy lifestyle to prevent and manage non-communicable chronic disease. However, it is also well recognised that participation in moderate to strenuous physical activity can be associated with an increased risk of sudden cardiac death and other life-threatening medical complications, particularly in endurance sports. In this regard, the CSEM group focused a substantial component of its research activity on strategies to reduce adverse medical events in the exerciser (SAFER studies). Several research studies have been concluded over the past 6 years in runners participating in a 21 km and a 56 km endurance event—the Two Oceans marathon races. In these studies, a higher rate of medical complications was identified, serious life-threatening medical complications were documented46 and several risk factors for medical complications were ascertained.47 ,48 As a result of these data, an online medical screening tool and educational intervention programme was developed to reduce the risk of medical complications in these recreational athletes. Finally, an extensive medical and injury history database in over 45 000 recreational runners has been compiled. These data form the basis of a prospective cohort study to identify risk factors for medical complications and injury in this group.

Development and implementation of a comprehensive lifestyle intervention programme for patients with lifestyle-related chronic diseases

The global health and economic burden of lifestyle-related chronic diseases are well established. Therefore, lifestyle intervention programmes aimed at the primary, secondary and tertiary (rehabilitation) level are imperative to reduce this burden. The IOC has recognised this, and actively promotes physical activity and lifestyle intervention in all population groups. Recently, there has been a call for the Sport and Exercise Medicine physician to play an active role in providing a clinical service that focuses on lifestyle intervention for chronic disease. Members of this research group have developed such a programme for patients with established chronic disease. This programme is both patient-centred (not disease-centred) and comprehensive (not single intervention). In this BJSM IPHP edition, this programme is described and the preliminary results are presented.49

The burden of injury and other health issues in specific athlete populations

The OSTRC has completed a number of cohort studies to describe the magnitude of the problem in their targeted sports as well as among elite athletes, recreational athletes and in youth and children's sport. Thus, there is a lot of data on the incidence, patterns and severity of acute time-loss injuries across most sports and levels of participation. The OSTRC has established key surveillance systems to monitor the rate of specific injury types or in specific sports, such as the Norwegian National Cruciate Ligament Register,50 the FIS Injury Surveillance System51 and the National Football Injury Surveillance System.52 These systems monitor changes in injury patterns over time. However, overuse injuries have largely been neglected so far, and although a consensus was reached on how to record and report data in epidemiological studies on injuries, the OSTRC has recently shown that this standard methodology does not capture overuse injuries. Overuse injuries may represent as much of a problem as do acute injuries in many sports,53 and this is the case not just among elite athletes but also among recreational athletes, runners and other ‘weekend warriors’. As a first step, the OSTRC has therefore developed and now validated new methods to quantify overuse injuries, taking advantage of new digital technology to record data directly from the athlete. These studies include a selection of team sports and endurance sports at different levels of participation. The second step is to employ this novel methodology to conduct prospective studies to measure the magnitude of key overuse problems in selected sports and at the same time study their risk factors.54 ,55 Such studies are ongoing, using handball, where shoulder problems and low back pain are prevalent, as a model. Also, a new PhD project on the young elite athlete has just started to monitor load and the risk of developing health issues over time.

Risk factors and mechanisms

The second step in the sequence of injury prevention is to map the causes of injuries, to identify their risk factors and mechanisms. The OSTRC has developed new research models and methods to describe and understand the inciting event, the mechanisms of injury, based on video recordings of actual injuries. Injury mechanisms among elite athletes are often the same as in recreational or youth sports and our approach takes advantage of the fact that in elite sports, injury mechanisms are often captured in detail by TV recordings. The OSTRC is the only research centre in the world systematically applying video analysis methods with novel model-based image-matching technology (POSER method) to a range of sports including handball, football, alpine skiing and snowboarding.56 ,57 This provides more precise descriptions of the mechanisms of sports injuries, for example, for knee injuries, than has previously been possible. The POSER method is now being used in a number of studies across different injury types and sports, and the OSTRC recently published the most compelling data that exist to explain the specific biomechanical underpinning of ACL injury in team sports and alpine skiing.58 ,59

Injury prevention and implementation

The final steps in injury prevention research are to introduce measures that are likely to reduce the future risk and/or severity of sports injuries and document whether they are effective, preferably by means of a randomised controlled trial. The Oslo Sports Trauma Research Center has completed six large-scale landmark studies in the field: a case–control study on helmet use in recreational snowboarders and alpine skiers,60 an intervention study on a balance training programme to prevent ACL injuries among female senior handball players,61 a randomised controlled trial on an exercise programme to prevent lower extremity injuries in youth handball players,62 an intervention study using a novel eccentric strength exercise programme to prevent hamstring strains in male football players,63 and two randomised controlled trials to develop a warm-up programme to prevent injuries among youth female football players.64 ,65 A general finding across most of these studies is that injury risk can be reduced by as much as 50% through such simple measures. Similarly, a recently published 10-year study on knowledge translation and implementation in Norwegian elite handball could reveal a sustained 50% reduction in ACL injury risk in Norwegian elite level handball.66