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Sex-based differences in helmet performance in bicycle trauma
  1. Joshua Feler1,
  2. Adrian A Maung2,
  3. Rick O'Connor3,
  4. Kimberly A Davis2,
  5. Jason Gerrard4
  1. 1 Department of Neurosurgery, Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA
  2. 2 Department of Surgery, Yale School of Medicine, New Haven, Connecticut, USA
  3. 3 Yale New Haven Health System, New Haven, Connecticut, USA
  4. 4 Department of Neurosurgery, Yale School of Medicine, New Haven, Connecticut, USA
  1. Correspondence to Dr Jason Gerrard, Department of Neurosurgery, Yale School of Medicine, New Haven, CT 0651, USA; jason.gerrard{at}yale.edu

Abstract

Objectives To determine the existence of sex-based differences in the protective effects of helmets against common injuries in bicycle trauma.

Methods In 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.

Results In 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.

Conclusions Bicycle 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.

  • gender
  • traffic
  • accidents

Data availability statement

Data may be obtained from a third party and are not publicly available. The NTDB is the property of the Committee on Trauma, American College of Surgeons and is available by application through its website. The authors will consider requests for additional materials made through email to the corresponding author.

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Data availability statement

Data may be obtained from a third party and are not publicly available. The NTDB is the property of the Committee on Trauma, American College of Surgeons and is available by application through its website. The authors will consider requests for additional materials made through email to the corresponding author.

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Footnotes

  • Twitter @jrfeler

  • Contributors JF performed the primary data analysis, wrote and edited the manuscript. AAM provided conceptual guidance in formulating the research questions and edited the manuscript. ROC provided conceptual guidance in formulating the research questions. KAD provided guidance in formulating the research questions and reviewed the manuscript. JG assisted with data analysis, provided guidance in formulating the research questions, mentored the first author and edited the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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