Re: Re: Objective observation of helmet use is essential
July 2006
The Editor, BMJ
Dear Sir,
With due respect the letter “Re: Objective observation of
helmet use is essential” from Diane and Robert S. Thompson, BMJ
Rapid Responses, July 8, is misleading at best and it must be asked, to turn
their own question around, “Are you really trying to pursue the science
assessing cycle helmet efficacy and population effectiveness or is this some
sort of crusade on your part to fit the science to your beliefs?”
Drs Thompson dismiss Robinson [d] as the studies reported
there are not primarily case-controlled ones, and suggest Robinson simply
ignores studies with which she does not agree. The New Zealand
Government’s compulsory experiment has undergone a cohort review
[b], which is less liable to selection bias and therefore stronger than a case-
control study [c]. Yet Drs Thompson and Hagel et al [i] appear to simply
dismiss it — does it not fit their beliefs?
In New Zealand a whole population of some 4 million people
have been either compelled to wear helmets while riding a bicycle or told not
to bicycle – despite health indications to the contrary the New
Zealand political message has solidly been that not bicycling is better than
doing so sans plastic hat. The population wide data in New Zealand should
show something like the often claimed, and just as often challenged, 85%
reduction in head injuries to bicyclists. It simply does not. This has been
reported in an earlier letter [a] in response to Hagel et al [i], that was based
on previous published data by Perry [b], and a similar analysis is also
provided by Robinson [d].
While some studies, particularly pre-legislation, have shown
some small benefits; other, later studies, have shown total failure. Benefit
cost studies have shown the costs swamping meagre benefits. It might be
nice if the helmet legislation had worked, but wishful thinking is not science
and doesn’t prevent injuries or improve health. Narrow case-
controlled studies seem to miss this big picture — across a whole
population the measure did not work.
New Zealand's problem is unfortunately that the experiment
was enforced by law, and political expedience doesn't allow the easy removal
of laws, even failed ones. Government policy is now to increase cycling, in
light of growing health issues such as child obesity, and they are battling
some twenty years of telling people the activity is extremely dangerous
— those charged with implementing this policy have publicly admitted
they created a problem for themselves.
The closing comments of Drs Thompson show how
unscientific the approach is. With due respect it might be easier simply to re-
word them slightly: “We predict [a review of research] will lead you to
the conclusion that we have reached, that kevlar vests prevent gunshot
injuries and increased wearing rates result in decreased gunshot injuries to
people”. Do people call for population-wide compulsory kevlar vests?
Of course not.
Those who oppose bicycle helmet legislation do not claim that
these plastic hats cannot prevent some injuries, to do so would be
unsupportable. Rather they oppose the legislation because it does not work
across a population to decrease injuries and increase health [b, d]. By
suggesting that those who oppose their view do so for a reason they do not,
Drs Thompson are being misleading at best.
What is revealing is how those who expound the plastic hat
wearing theory, namely that they are so effective at reducing head injuries
that to not do so is unwise at best, actually practice their own theory. It has
long been known that the theory does not only apply to those on bicycles,
those involved in anything from walking to driving have at times been
extolled, or forced, to wear “bicycle style” plastic hats.
Back in 1997 the Australian Government published research
claiming that if seat-belted, airbag-protected, car occupants wore bicycle-
style helmets a saving of A$380M/year would accrue from reduce head
injuries, rising to A$500M/year without airbags [g]. Since then they have
continued to pursue research in this area [h].
In 2003 the New Zealand Minister of Transport wrote that the
Government “does not dispute that helmet wearing could reduce the
severity of head injury for car occupants in crashes. However, given the
currently extremely low level of helmet wearing by car occupants, the
introduction and enforcement of mandatory helmet wearing would be
impracticable.” [f]
Ignoring that the NZ Government had supported a decade long
campaign to persuade bicyclists to wear helmets so that legislation would
become practicable, we need to ask why is there such a low level of helmet
wearing in cars given the claims by Drs Thompson that those driven by
science and not belief support the plastic hat theory? Where are all those
scientists in cars wearing helmets? They do exist; for example Dr Jack
McClean, director of the National Health and Medical Research
Council’s road accident research unit in Adelaide has happily been
photographed with helmet on in the car [e]; but they remain the exception
rather than the rule.
“You should wear a helmet, and the law should compel
you to do so, but we choose not to ourselves even when our theory says we
should.” Science or something else?
Selected case-control studies, the ignoring of trends, and the
dismissal of population wide failures. With all due respect, is this really
science?
Let us not forget that during the 3rd International Conference
on Injury Prevention and Control, Melbourne 1995, that delegates from
Sweden stated, tearfully, that their helmet promotion activities had result in
deaths. The Drs Thompson where present I believe. The response to this
tragedy was to develop a helmet that fell off on impact. Science or belief?
It is clear that were the NZ Legislature driven by science and
not political expedience the health, safety & financial disaster that is the
NZ Bicycle Helmet legislation would long have been abandoned. The British
medical profession should be taking note of this and act to ensure that a
similar disaster is not visited upon the British by the “Martlew
Bill” or anything else.
[d] Robinson, D. L., No clear evidence from countries
that have enforced the wearing of helmets, BMJ 2006;332:722-725
[e] Innes, Stuart, A new head start for car safety,
Adelaide Advertiser, 20 May 1993
[f] Hon Paul Swain, Minister of Transport, New Zealand, Letter To: Hon Peter Dunne, Leader, United Future, 28 May
2003
[g] McClean, A. J, et al, Prevention of Head Injuries to
Car Occupants, Federal Office of Road Safety, CR 160, ISBN 0 642
51349 X, 1997
[h] Anderson, R., et al, Further Development of a
Protective Headband for Car Occupants, Australian Transport Safety
Bureau, CR 205, ISBN 0 642 25574 1, 2001
[i] Hagel, B., Macpherson, A., Rivara, F. P., Pless, B., Arguments against helmet legislation are flawed, BMJ
2006;332:725-726
Rapid Response:
Re: Re: Objective observation of helmet use is essential
July 2006
The Editor, BMJ
Dear Sir,
With due respect the letter “Re: Objective observation of
helmet use is essential” from Diane and Robert S. Thompson, BMJ
Rapid Responses, July 8, is misleading at best and it must be asked, to turn
their own question around, “Are you really trying to pursue the science
assessing cycle helmet efficacy and population effectiveness or is this some
sort of crusade on your part to fit the science to your beliefs?”
Drs Thompson dismiss Robinson [d] as the studies reported
there are not primarily case-controlled ones, and suggest Robinson simply
ignores studies with which she does not agree. The New Zealand
Government’s compulsory experiment has undergone a cohort review
[b], which is less liable to selection bias and therefore stronger than a case-
control study [c]. Yet Drs Thompson and Hagel et al [i] appear to simply
dismiss it — does it not fit their beliefs?
In New Zealand a whole population of some 4 million people
have been either compelled to wear helmets while riding a bicycle or told not
to bicycle – despite health indications to the contrary the New
Zealand political message has solidly been that not bicycling is better than
doing so sans plastic hat. The population wide data in New Zealand should
show something like the often claimed, and just as often challenged, 85%
reduction in head injuries to bicyclists. It simply does not. This has been
reported in an earlier letter [a] in response to Hagel et al [i], that was based
on previous published data by Perry [b], and a similar analysis is also
provided by Robinson [d].
While some studies, particularly pre-legislation, have shown
some small benefits; other, later studies, have shown total failure. Benefit
cost studies have shown the costs swamping meagre benefits. It might be
nice if the helmet legislation had worked, but wishful thinking is not science
and doesn’t prevent injuries or improve health. Narrow case-
controlled studies seem to miss this big picture — across a whole
population the measure did not work.
New Zealand's problem is unfortunately that the experiment
was enforced by law, and political expedience doesn't allow the easy removal
of laws, even failed ones. Government policy is now to increase cycling, in
light of growing health issues such as child obesity, and they are battling
some twenty years of telling people the activity is extremely dangerous
— those charged with implementing this policy have publicly admitted
they created a problem for themselves.
The closing comments of Drs Thompson show how
unscientific the approach is. With due respect it might be easier simply to re-
word them slightly: “We predict [a review of research] will lead you to
the conclusion that we have reached, that kevlar vests prevent gunshot
injuries and increased wearing rates result in decreased gunshot injuries to
people”. Do people call for population-wide compulsory kevlar vests?
Of course not.
Those who oppose bicycle helmet legislation do not claim that
these plastic hats cannot prevent some injuries, to do so would be
unsupportable. Rather they oppose the legislation because it does not work
across a population to decrease injuries and increase health [b, d]. By
suggesting that those who oppose their view do so for a reason they do not,
Drs Thompson are being misleading at best.
What is revealing is how those who expound the plastic hat
wearing theory, namely that they are so effective at reducing head injuries
that to not do so is unwise at best, actually practice their own theory. It has
long been known that the theory does not only apply to those on bicycles,
those involved in anything from walking to driving have at times been
extolled, or forced, to wear “bicycle style” plastic hats.
Back in 1997 the Australian Government published research
claiming that if seat-belted, airbag-protected, car occupants wore bicycle-
style helmets a saving of A$380M/year would accrue from reduce head
injuries, rising to A$500M/year without airbags [g]. Since then they have
continued to pursue research in this area [h].
In 2003 the New Zealand Minister of Transport wrote that the
Government “does not dispute that helmet wearing could reduce the
severity of head injury for car occupants in crashes. However, given the
currently extremely low level of helmet wearing by car occupants, the
introduction and enforcement of mandatory helmet wearing would be
impracticable.” [f]
Ignoring that the NZ Government had supported a decade long
campaign to persuade bicyclists to wear helmets so that legislation would
become practicable, we need to ask why is there such a low level of helmet
wearing in cars given the claims by Drs Thompson that those driven by
science and not belief support the plastic hat theory? Where are all those
scientists in cars wearing helmets? They do exist; for example Dr Jack
McClean, director of the National Health and Medical Research
Council’s road accident research unit in Adelaide has happily been
photographed with helmet on in the car [e]; but they remain the exception
rather than the rule.
“You should wear a helmet, and the law should compel
you to do so, but we choose not to ourselves even when our theory says we
should.” Science or something else?
Selected case-control studies, the ignoring of trends, and the
dismissal of population wide failures. With all due respect, is this really
science?
Let us not forget that during the 3rd International Conference
on Injury Prevention and Control, Melbourne 1995, that delegates from
Sweden stated, tearfully, that their helmet promotion activities had result in
deaths. The Drs Thompson where present I believe. The response to this
tragedy was to develop a helmet that fell off on impact. Science or belief?
It is clear that were the NZ Legislature driven by science and
not political expedience the health, safety & financial disaster that is the
NZ Bicycle Helmet legislation would long have been abandoned. The British
medical profession should be taking note of this and act to ensure that a
similar disaster is not visited upon the British by the “Martlew
Bill” or anything else.
Yours,
N
Perry, Scientist & Mathematician, New Zealand
[a] Perry, N. Letter to BMJ, March 2006, available at http://kaka.research.zoot.net/bmj/march_letter.html
[b] Perry, N., The Bicycle Helmet Legislation, Curse or
Cure?, Cycling 2001, Christchurch.
[c] For example, see the hierarchy of evidence in
“Systematic reviews: what are they and why are they useful?” at http://www.shef.ac.uk/scharr/ir/units/systrev/
hierarchy.htm
[d] Robinson, D. L., No clear evidence from countries
that have enforced the wearing of helmets, BMJ 2006;332:722-725
[e] Innes, Stuart, A new head start for car safety,
Adelaide Advertiser, 20 May 1993
[f] Hon Paul Swain, Minister of Transport, New Zealand,
Letter To: Hon Peter Dunne, Leader, United Future, 28 May
2003
[g] McClean, A. J, et al, Prevention of Head Injuries to
Car Occupants, Federal Office of Road Safety, CR 160, ISBN 0 642
51349 X, 1997
[h] Anderson, R., et al, Further Development of a
Protective Headband for Car Occupants, Australian Transport Safety
Bureau, CR 205, ISBN 0 642 25574 1, 2001
[i] Hagel, B., Macpherson, A., Rivara, F. P., Pless, B.,
Arguments against helmet legislation are flawed, BMJ
2006;332:725-726
Competing interests:
None declared
Competing interests: No competing interests