Sex-based differences in helmet performance in bicycle trauma

ObjectivesTo determine the existence of sex-based differences in the protective effects of helmets against common injuries in bicycle trauma.MethodsIn a retrospective cohort study, we identified patients 18 years or older in the 2017 National Trauma Database presenting after bicycle crash. Sex-disaggregated and sex-combined multivariable logistic regression models were calculated for short-term outcomes that included age, involvement with motor vehicle collision, anticoagulant use, bleeding disorder and helmet use. The sex-combined model included an interaction term for sex and helmet use. The resulting exponentiated model parameter yields an adjusted OR ratio of the effects of helmet use for females compared with males.ResultsIn total, 18 604 patients of average age 48.1 were identified, and 18% were female. Helmet use was greater in females than males (48.0% vs 34.2%, p<0.001). Compared with helmeted males, helmeted females had greater rates of serious head injury (37.7% vs 29.9%, p<0.001) despite less injury overall. In sex-disaggregated models, helmet use reduced odds of intracranial haemorrhage and death in males (p<0.001) but not females. In sex-combined models, helmets conferred to females significantly less odds reduction for severe head injury (p=0.002), intracranial bleeding (p<0.001), skull fractures (p=0.001), cranial surgery (p=0.006) and death (p=0.017). There was no difference for cervical spine fracture.ConclusionsBicycle helmets may offer less protection to females compared with males. The cause of this sex or gender-based difference is uncertain, but there may be intrinsic incompatibility between available helmets and female anatomy and/or sex disparity in helmet testing standards.

Estimated total costs from non-fatal and fatal bicycle crashes in the USA: 1997–2013

IntroductionEmergency department visits and hospital admissions resulting from adult bicycle trauma have increased dramatically. Annual medical costs and work losses of these incidents last were estimated for 2005 and quality-of-life losses for 2000.MethodsWe estimated costs associated with adult bicycle injuries in the USA using 1997–2013 non-fatal incidence data from the National Electronic Injury Surveillance System with cost estimates from the Consumer Product Safety Commission's Injury Cost Model, and 1999–2013 fatal incidence data from the National Vital Statistics System costed by similar methods.ResultsApproximately 3.8 million non-fatal adult bicycle injuries were reported during the study period and 9839 deaths. In 2010 dollars, estimated adult bicycle injury costs totalled $24.4 billion in 2013. Estimated injury costs per mile bicycled fell from $2.85 in 2001 to $2.35 in 2009. From 1999 to 2013, total estimated costs were $209 billion due to non-fatal bicycle injuries and $28 billion due to fatal injuries. Inflation-free annual costs in the study period increased by 137% for non-fatal injuries and 23% for fatal injuries. The share of non-fatal costs associated with injuries to riders age 45 and older increased by 1.6% (95% CI 1.4% to 1.9%) annually. The proportion of costs due to incidents that occurred on a street or highway steadily increased by 0.8% (95% CI 0.4% to 1.3%) annually.ConclusionsInflation-free costs per case associated with non-fatal bicycle injuries are increasing. The growth in costs is especially associated with rising ridership, riders 45 and older, and street/highway crashes.