Bicycling opportunities and injury risk–both are about exposure

Guest blog by @CarolineFinch

Cross Fertilising ‘Injury Prevention’ journal (IP) and BJSM



One of the most researched areas in road safety and injury prevention is that of bicyclist safety. In fact, my own initial foray into injury prevention research in the early 1990s was as a member of the team that evaluated the population-level impact of the first mandatory bicycle helmet wearing law (1). The topic of bicycle helmet effectiveness remains a topic of much debate despite much evidence that they are effective if worn correctly. Bicycling is also a major focus of current active transportation and physical activity research.

The February 2011 issue of Injury Prevention includes several papers relating to bicycling injury that are of relevance to anyone interested in increasing this form of physical activity. The first paper, by Poulos et al. presents the protocol of study that aims to describe the incidence of crashes, near-misses and injury rates in relation to bicyclist exposure factors including the time and distance travelled and the type of road infrastructure used. As the authors point out it is not fully obvious which type of bicycling infrastructure provides overall best safety gains and this needs further research. They cite the example that paths that are designed to protect bicyclists from road traffic, but which enable sharing by bicyclists and pedestrians, may in fact increase total injury rates due to collisions with pedestrians in which either type of oath user is injured. The study plans to recruit people who self-identify as active bicyclists and then to conduct two-monthly follow-up surveys with them to collect information about their bicycling habits and injury experiences.

Another paper in the same issue, by Ackery and colleagues, describes a case-control study of bicyclist deaths in the USA e documented as part of the well-established national Fatality Analysis Reporting System. This system includes all fatal crashes involving a motor vehicle on public roadways and so the bicyclist injuries were all the result of a collision with a motor vehicle. The study explored a range of exposure factors such as travel time of day, posted speed limits, and the type of vehicle collided with in both fatal cases and controls who were non-bicyclist road deaths. The most significant finding was that a disproportionately high proportion of the bicyclist deaths, compared to controls, involved larger and more expensive vehicles. The authors concluded that transportation policy should consider strategies to separate bicyclists from other very large road users.

The first French case-control study of helmet wearing and bicyclist injuries is described in a paper by Amoros et al. All study participants were recruited from a road trauma registry, with cases being bicyclists with a head injury and the control being bicyclists without head or neck injuries. Exposure to particular road infrastructure at the time of injury was collected in terms of the crash setting being on an urban or rural road and the type of road (as being major, local, or “off”). Evidence from this study is in support of the protective benefits of helmets.

As with all areas of physical activity promotion, there is a very clear and strong overlap with injury prevention. The bicycling context provides a graphic example of how increased exposure to a given ideal behaviour (e.g. in terms of duration of activity), can also increase the risk of adverse outcomes such as injury. Injury researchers have long known this and have a history of well-developed robust methods for measuring bicyclist exposure (e.g. in (1)). The success of active transportation as a physical activity will depend on there being suitable safe infrastructure and environments for the bicycling to occur in and the amount of bicycling (or exposure to positive physical activity) that ensues will be directly related to this. Conversely, increased exposure to hazards within those same environments, whether due to longer amounts of accumulated time spent bicycling or bicycling in settings with particularly high traffic volumes or poor road conditions, can lead to increased risk of bicycling injury. Active transportation policy developments will need to consider the provision of infrastructure to protect and support the needs of all road users, including those who wish to use it for their physical activity benefits, rather than just as a means of getting from a to b.

Additional reference
(1) Cameron MH, Vulcan PA, Finch CF, Newstead SV. Mandatory bicycle helmet use following a decade of helmet promotion in Victoria, Australia – an evaluation. Accident Analysis and Prevention. 1994, 26:325-337.

Caroline Finch is an injury prevention researcher from the Australian Centre for Research into Injury in Sport and its Prevention (ACRISP) within the Monash Injury Research Centre, Monash University, Australia. She specialises in implementation and dissemination science applications for sports injury prevention. She is the Senior Associate Editor for Implementation & Dissemination for the British Journal of Sports Medicine and a member of the Editorial Board of Injury Prevention; both journals are published by the BMJ Group. Caroline can be followed on Twitter @CarolineFinch.

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