Intended for healthcare professionals

Rapid response to:

Analysis And Comment

Arguments against helmet legislation are flawed

BMJ 2006; 332 doi: https://doi.org/10.1136/bmj.332.7543.725 (Published 23 March 2006) Cite this as: BMJ 2006;332:725

Rapid Response:

The case for compulsory cycle helmets is not made

1. The original paper shows that the case for cycle helmets is as
strong, or as weak, as for driving helmets or walking helmets. Anyone
seeking to compel cyclists to wear helmets needs to explain why they are
not doing the same to drivers and pedestrians.

2. The critique is starting from the wrong premise: that helmets are
good and it is necessary to prove that helmet compulsion would do harm. It
is actually up to the compulsionists to prove that compulsion would do
good that outweighs the costs it imposes on society.

In trying to minimise the health benefits of regular cycling, the
authors appear to have conceded that helmet compulsion reduces cycling.
Reductions in cycling also cost society in pollution and traffic
congestion, so even if their health argument is valid, it does not follow
that reductions in cycling do not matter.

3. The first paragraph of the critique seems to say that helmets are
very helpful in improving cyclists' safety, but the words used don't. It
says:

"protective association" - not "causal relationship"

"protective effect" - not "reduction in fatal and serious injuries"

"reduction in head injuries" - not "head injury rate reduction"

"reduction in head injuries" - not "greater reduction than in other
comparable groups"

"reduction in head injuries" - not "greater reduction than other
injury types"

The Robinson paper clearly shows that the only changes proven to have
occurred after enforcement of compulsory cycle helmet laws are:
(1) fewer people cycling
(2) a higher proportion of remaining cyclists wearing helmets.

4. Hagel and colleagues appear to believe that questioning Robinson's
suggested reasons why cycle helmets are ineffective (in preventing serious
injury) invalidates the measured casualty data.

The null hypothesis in this situation is "cycle helmets don't protect
heads against serious injuries." Cycle helmet compulsion can only be
justified if this hypothesis can be disproved.

Colin McKenzie

Competing interests:
I do some work as a self-employed cycle trainer for Cycle Training UK, who have a 'helmets optional' policy.

Competing interests: No competing interests

27 March 2006
Colin G McKenzie
cycling officer and cycle trainer
26 NW10 7DS