Canada: helmet laws have made little difference to head injuries

A recent Canadian study found that bicycle helmet laws had little effect on head injuries. The study analysed 14 years of data, comparing provinces with and without helmet laws. Unlike other studies in this field, it attempts to remove the effect of confounding factors by controlling for background trends and modelling head injuries as a proportion of all cycling injuries. It concludes:

the incremental contribution of provincial helmet legislation to reduce the number of hospital admissions for head injuries is uncertain to some extent, but seems to have been minimal.

This study has been reported here:

“(the study) analyzed the rate of cycling-related hospital admissions for head injuries across the country between 1994 and 2008 — an enormous research sample of more than 66,000 people…

What they found initially seemed to suggest that this legislation improved public safety…

But upon closer inspection, according to Dennis and company, this positive effect failed to stand. On the contrary, the researchers concluded that head injuries were decreasing across the country at a rate that wasn’t “appreciably altered” by the new helmet laws. Other rider health initiatives — namely, public safety campaigns and the introduction of better bike infrastructure — rendered the contribution of helmet laws “minimal” …

Mandatory helmet laws, meanwhile, may discourage riding to the point where public safety as a whole suffers from the relative decrease in physical exercise.”

The effect is consistent with an analysis of cycling fatalities in Canada, that concludes:

It is apparent that mass helmet use is not contributing to the reduction in cyclist fatalities, at least not in any measurable way. The results suggest that traffic authorities should refocus to put their efforts into other proven measures.

The study contradicts other studies that had claimed a benefit from helmet legislation in Canada. However, many of these studies have serious methodological flaws rendering their claims invalid. Often, such studies are done by helmet advocates keen to “prove” their beliefs, with a disturbing lack of scientific discipline.

This has led Ben Goldacre, an epidemiologist, to provide an insightful overview of the challenges of evaluating the effectiveness of helmet legislation:

Standing over all this methodological complexity is a layer of politics, culture, and psychology. Supporters of helmets often tell vivid stories about someone they knew, or heard of, who was apparently saved from severe head injury by a helmet. Risks and benefits may be exaggerated or discounted depending on the emotional response to the idea of a helmet. For others, this is an explicitly political matter, where an emphasis on helmets reflects a seductively individualistic approach to risk management (or even “victim blaming”) while the real gains lie elsewhere. It is certainly true that in many countries, such as Denmark and the Netherlands, cyclists have low injury rates, even though rates of cycling are high and almost no cyclists wear helmets. This seems to be achieved through interventions such as good infrastructure; stronger legislation to protect cyclists; and a culture of cycling as a popular, routine, non-sporty, non-risky behaviour.

Helmet laws are ineffective compared to other safety measures. As the safest cycling countries demonstrate, other measures are far more effective to reduce injuries. Helmet laws seem to contribute little to safety, while reducing cycling and taking the focus away from more effective measures.

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