Factors affecting severity of bicycle-related injuries: The role of helmets in preventing head injuries

Objectives: To identify factors that affect the severity of bicycle-related injuries in patients with head injury compared with those without, so as to find whether the effect of using helmets extends beyond head protection, and to explore a direct protective effect of helmets on head injuries. Methods: A total of 297 patients with bicycle-related injuries were studied. A generalized linear model was used to test the effect of age, sex, helmet use, cause of injury, year of injury, place of injury and whether the injury occurred on public or school holidays on the Injury Severity Score (ISS) in those patients who had head injury and those without. A logistic regression model was used to define the factors that contribute to head injury, while adjusting for ISS. Results: Factors affecting ISS in the generalized linear model in those who had head injury were: cause of injury (P = 0.01) and there was a trend for helmet use (P = 0.06). The significant factors that have affected ISS in the no head injury group were age (P = 0.002) and place of accident (P = 0.03). Logistic regression has shown that with each increase of 1 point in the ISS the odds of head injury increases by a factor of 1.22 (95% confidence interval 1.13-1.31) and the use of helmets reduces the odds of head injury by a factor of 0.48 (95% confidence interval 0.23-1.03). Conclusions: The reduced severity of injury in helmeted patients is because of protection of the head and not other body regions.