BMJ  2006;332:852 (8 April), doi:10.1136/bmj.332.7545.852-a

Letter

Do enforced bicycle helmet laws improve public health?

Evidence is conflicting

EDITOR—Hagel et al cite six, mostly old, "independent" studies that support their views.¹ Two are their own and another, after correction of an agreed mathematical error finds that helmets provide 186% protection—a clear case of major confounding.

Curiously they omit any reference to the many studies that don't support their views. For example, there is no reference to Rodgers' study of 8 million cyclists in the US that found "the bicycle-related fatality rate is positively and significantly correlated with increased helmet use,"² in line with the findings of Robinson and others for New Zealand and Australia. Neither is there a reference to recent work by Hewson analysing UK police and hospital statistics.^{3 4} Hewson states. "The conclusion cannot be avoided that there is no evidence from the benchmark dataset in the UK that helmets have had a marked safety benefit at the population level for road using pedal cyclists."³ And, as has been shown in the Netherlands, you can achieve the lowest cyclist head injury rate in the world with helmets being worn by only one in 1000 of your cyclists.

Whatever the truth about helmets, cycling is an extremely safe activity with a lower head injury rate per km than walking. Head injuries form a lower proportion of all child cyclist hospital admissions in England (38%) than for child pedestrian admissions (44%). Cyclists represent just 7% of all hospital head injury admissions exceeded by trips and falls (42%) and even assaults (11%). One has to wonder therefore why cyclists merit singling out for intervention with helmets.

Those who press us down the path of helmet compulsion in the face of the clearly conflicting evidence have failed to learn the lessons of hormone replacement therapy.⁵

Melbourn, Royston, Hertfordshire SG8 6BN tony{at}raven-family.com

---

Competing interests: None declared.

References

1. Hagel B, Macpherson A, Rivara FP, Pless B. Arguments against helmet legislation are flawed. BMJ 2006;332: 725-6. (25 March.)[Free Full Text]
2. Rodgers GB. Reducing bicycle accidents: a re-evaluation of the impacts of the CPSC bicycle standard and helmet use, Journal of Products Liability 1988;11; 307-17.
3. Hewson PJ. Cycle helmets and road casualties in the UK. Traffic Injury Prevention 2005;6; 127-34.[Medline]
4. Hewson PJ. Investigating population level trends in head injuries amongst child cyclists in the UK. Accident Analysis and Prevention 2005;37; 807-15.[CrossRef]
5. Petitti D. Hormone replacement therapy and coronary heart disease: four lessons. Int J Epidemiol 2004;33: 461-3.[Free Full Text]

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

Relevant Article

Arguments against helmet legislation are flawed

Brent Hagel, Alison Macpherson, Frederick P Rivara, and Barry Pless
BMJ 2006 332: 725-726. [Full Text] [PDF]