Bicyclists injured by automobiles: helmet use and the burden of injury

Background: Given the widespread use of bicycles on public roadways, bicyclists injured in automobile collisions present a familiar problem to trauma centers worldwide. The aims of this study are to characterize the current injury patterns and to quantify independent risk factors for preventable injury and death, with a focus on helmet utilization and traumatic brain injuries. Methods: This is a retrospective study using the American College of Surgeons Trauma Quality Improvement Program database for the period 2010 to 2016. Data were abstracted for bicyclists ≥16 years of age injured by an automobile. The primary outcome of interest was mortality. The secondary outcomes included intracranial, facial, and cervical spine injuries, as well as polytrauma. We used multivariate logistic regression to identify risk factors associated with outcomes. Results: Of the 980 955 cases in the database, 7159 (0.73%) were bicyclists involved in a collision with an automobile. The median age was 45 years and 85% of patients were male. Polytraumatic occurrences accounted for 58% of injuries. Helmet use was reported in 25.4% of cases, a rate that did not change significantly during the study period. Helmet utilization was higher in those aged >65 years and in patients located in the West and Northeast regions of the USA. Helmet use was associated with an overall lower incidence of all reported forms of intracranial injuries. Overall mortality was 7.4%. Independent risk factors associated with mortality included age >65, lack of helmet use, head injury, and abdominal injury. Discussion: Bicyclists injured in collisions with an automobile are at high risk of severe injury and mortality. Preventive strategies should target older bicyclists, helmet utilization, and increasing helmet accessibility for all bicyclists using roadways. Level of evidence: Level IV.