Richard Keatinge in the Irish Medical Times

url:http://www.imt.ie/displayarticle.asp?AID=5724&NS=1&SID=1

On balance, cycle helmets do not show the benefits that some have
claimed

Dr Richard Keatinge says that at best helmets protect against a few,
mostly minor, injuries. But, since he started looking at the evidence,
he has not worn his.

================================================== ====================

I cycle regularly to my practice, partly to set a good example to my
patients, partly to keep my middle-age spread at bay, but mostly
because I enjoy it. There is good evidence for the health benefits of
cycling and, anyway, without my spin, I would never hear the skylarks
singing.

Three hours of ordinary commuter cycling per week – 15 minutes each
way, perhaps three miles a day or 30 miles a week – reduced death
rates by nearly half, about 40 per cent. (Andersen LB, Schnohr P,
Schroll M, Hein HO, All-Cause Mortality Associated With Physical
Activity During Leisure Time, Work, Sports, and Cycling to Work. Arch
Intern Med. 2000; 160:1621-1628).

Even among keen sportsmen in this study, cycling reduced death rates
(pers. comm. Prof Andersen). There are very few other interventions
that can have such a dramatic effect on health.

Danger

My family worried about the danger on the roads. For careful riders
the risk is real, but it is small. In England and Wales, one cyclist
dies for every 23 million miles cycled. (Passenger death rates: by
mode of transport 1981-1999: Social Trends 31. www.statistics.gov.uk.)

If I cycle 30 miles most weeks, for 50 years, I have one chance in 440
of dying as a result. That is not negligible, but it is many times
less than the health benefits.

Common sense?

I bought a cycle helmet. It seemed obvious that it was a good idea. I
wore it for a while. It was hot, heavy, and sweaty. I did not enjoy
wearing it. I started looking at the evidence that cycle helmets
actually do much good.

It is easy to find sales literature from helmet manufacturers
(www.bellbikehel mets.com).

It is also easy to find well-meaning enthusiasts who would like to
save cyclists (www.bhit.org). Genuine evidence is difficult to
extract, even from the professional literature.

Limited usefulness

Some hopeful figures are often quoted (“85 per cent” and up). They
turn out to have a very poor scientific base. One early study compared
helmeted children, mostly white, well-off, and cycling in parks, with
unhelmeted children, mostly black, cycling in busy urban streets.

The latter had more injuries, including head injuries. No amount of
statistical manipulation can turn that sort of data into sound
conclusions on the effect of helmets. Unfortunately, they have been
widely quoted.

There are other and better case-control studies in the helmet
literature, e.g. Maimaris et. al. (Maimaris C, Summers CL, Browning C,
Palmer CR. Injury patterns in cyclists attending an accident and
emergency department: a comparison of helmet-wearers and non-wearers.
BMJ 1994;308: 1537-40).

They are based only on cyclists presenting with injuries. In these
studies, those who said they were wearing helmets were less likely to
have injuries recorded to their heads. (Thompson DC, Rivara FP,
Thompson R. Helmets for preventing head and facial injuries in
bicyclists (Cochrane Review). In: The Cochrane Library, Issue 3, 2004.
Chichester, UK: John Wiley & Sons, Ltd.)

The odds ratios for protection are in the neighbourhood of 75 per
cent. That sounds good. These papers often conclude that cycle helmets
are a good thing, which should be encouraged or even made compulsory.
However, there are words of caution to anyone reading these studies.

They often use the term “serious” head injury to mean anyone attending
hospital, or admitted for observation overnight. In a sense that is
correct; some of us have seen cyclists very upset, with scalp grazes
and gashes, and a large proportion would be admitted to rule out
intra-cerebral bleeding. But very few actually suffer any long-term
effects, apart from increased wisdom.

More evidence is required to show that cycle helmets are useful in the
real world. It should be possible to identify people who suffered
serious injury, or death, that could have been prevented by helmets.
And it should be possible to show, after a large increase in helmet
wearing, that the proportion of head injuries has declined.

Deaths and design

of helmets

In London, more than two-thirds of all cyclist deaths were due to
collision with a heavy good vehicle, 97 per cent with a motor vehicle
of some sort. (Gilbert K, McCarthy M. Deaths of cyclists in London
1985-92: the hazards of road traffic. BMJ 1994;308:1534-1537).

I have no access to post-mortem reports, but one may doubt that any
helmet could save the majority of cyclists killed by a heavy goods
vehicle.

Cycle helmets are not designed to protect against most serious
impacts. Design standards involve dropping them from a height of a
metre or so, directly onto a hard surface. The design intention is
that the foam should compress, thus slowing deceleration of the head.
Some of our patients may produce stories about damaged helmets, with
the implication that the helmet has avoided a much worse problem.

In fact, it requires very little energy to break a helmet, even to
smash it. Most broken helmets have simply failed.

Controversy and wiggly lines

Cycle helmets arouse strong feelings and violent disagreements. In one
study of trends in head injury, in a period when helmet use was
increasing, we read: “The wearing of a cycle helmet is estimated to
prevent 60 per cent of head injuries” (Cook A. Sheikh A. Trends in
serious head injuries among English cyclists and pedestrians. Injury
Prevention. 9(3): 266-7, 2003).

However, another paper concludes that “increased helmet wearing
percentages has had little association with serious head injuries to
cyclists” (Scuffham PA. Langley JD. Trends in cycle injury in New
Zealand under voluntary helmet use. Accident Analysis & Prevention.
29(1):1-9, 1997). Why are there such direct contradictions?

These studies are of trends in injury or death ratios over time. Such
ratios vary considerably from year to year. In general, we cannot
account in detail for most of the variations.

Any statistician will point out that relatively rare events, such as
cyclist deaths, will inevitably show considerable random variation
from year to year.

It can be easy to find an expected answer, merely by selecting the
time period of the study, selecting the age-groups to be analysed,
choosing the variables to be adjusted for, and so on.

At www.cyclehelmets.org there is a re-analysis of the data from one
time-trend study. The original concluded that a helmet law had been
“an effective road safety intervention”. The re-analysis, over a
longer time period, suggests strongly that any apparent benefit is an
artifact.

Costs of encouraging

helmets

Few studies make these explicit. But enforcement has costs. The most
obvious one is the expense of helmets. As one enthusiastic retailer
put it: “Just think, an accessory that isn’t particularly cheap and
that everyone has to buy”. That, at least, can be calculated, and if
it is a worthwhile expense, paid for by public funds.

But the main impact on health would come from an effect on the numbers
of people cycling. Even a small decline in the numbers cycling would
do more harm than preventing all injuries to cyclists.

To repeat, cycling is good for health. It does far more good than
associated injuries do harm.

The work reviewed at www.cyclehelmets.org strongly suggests that
overall, cycling in Australia declined by about a third after a helmet
law was passed. This would be enough to make the law extremely bad for
health, even if it prevented all injuries to cyclists.

There are other worrying possibilities, including the likelihood that
the law may increase risk to the remaining cyclists (Wardlaw M. Three
lessons for a better cycling future. BMJ 2000;321:1582-5).

It has been suggested that “just one” serious injury saved would be
enough to justify any amount of cost. No economist would agree. But no
health worker should agree either. The costs are not only money, but
are people dying with the consequences of insufficient exercise.

With the present political worries about obesity, politicians too may
think it unwise to criminalise people out for a healthy ride.

Compulsion

Some countries have forced cyclists to wear helmets or stop cycling. A
full analysis of the natural experiments provided by these laws would
be difficult. It should include head injuries and other injuries, to
cyclists, pedestrians, and other road users, in relation to the amount
of time they spend on the roads.

It should analyse these over a long time-period, using as potential
explanatory variables not only changes in helmet use, but also road
safety initiatives. And it should include costs.

In particular, putting people off cycling is a threat to health far
greater than any possible benefit that helmets could provide.

I have not found any comprehensive analysis of these factors in the
literature. In many cases, laws appear to have been declared a success
without serious evaluation. But some figures are available.

A graph (from www.cycle helmets.org) shows some figures from Western
Australia, which made cycle helmets compulsory in 1991.

It is not clear why the ratio of head injury among pedestrians showed
changes around the time of a helmet law. Nor is it clear why there is
a downward trend for all groups over most of this period. But there is
certainly no obvious benefit from the helmet law.

There are few reasonably thorough analyses of helmet lawsand some of
the best attempts may be found at www.cyclehelmets.org and
www.cycle-helmets.com. But, if the case-control studies are a good
guide to what happens in real life, the benefits should be obvious.

There are no obvious benefits. It is necessary to indulge in
disputable selection of the data in order to show any useful effect on
any parameter.

On balance, and admitting that the evidence is often unsatisfactory,
cycle helmets do not show the benefits that some have claimed.

To wear?

Since I started looking at the evidence, I have not worn my helmet. If
I am worried about my health, I should get on my bike. If I am worried
about accidents, I would follow the advice in Cyclecraft (Franklin J,
HMSO, 1997). If I am worried about my patients’ health, I tell them to
consider how they could use a bike in their daily lives, to listen to
the skylarks again, and wear a helmet if they actually want to.

To compel?

At best, cycle helmets protect against a few, mostly minor, injuries.
At worst, and especially when enforced, they contribute to the obesity
epidemic.

The evidence suggests that helmet laws are bad for health. In a world
which bombards politicians with complicated and worrisome issues, here
is one with a simple resolution – ignore cycle helmets.

There is much that can be done to make cycling a safer and commoner
choice. Helmets are not a useful part of that process.

Dr Richard Keatinge,

MRCGP, MFPH

www.keatinge.net
Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

wrote:

[snip]

Very interesting read.

For us, as commited cyclists, I think the answer is: we already cycle,
and we're going to cycle pretty much no matter what, so wear the helmet.

--
Callas

On Mon, 9 Aug 2004 21:52:06 +0100, Callas wrote:

wrote:

[snip]

Very interesting read.

For us, as commited cyclists, I think the answer is: we already cycle,
and we're going to cycle pretty much no matter what, so wear the helmet.

Who said you could speak for me? The known dangers of risk compensation
mitigate against wearing helmets, don't they?

--
Michael MacClancy
Random putdown - "His mother should have thrown him away and kept the
stork." - Mae West
www.macclancy.demon.co.uk
www.macclancy.co.uk

On Mon, 9 Aug 2004 21:52:06 +0100, Callas
wrote in message :

For us, as commited cyclists, I think the answer is: we already cycle,
and we're going to cycle pretty much no matter what, so wear the helmet.

Which neatly ignores risk compensation and the fact that helmets are
Not Terribly Comfortable :-)

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

"Callas" wrote in message
...
wrote:

[snip]

Very interesting read.

For us, as commited cyclists, I think the answer is: we already cycle,
and we're going to cycle pretty much no matter what, so wear the helmet.

********. As a committed cyclist, I want my experience to me as pleasant as
possible. I spend time and money on getting a bike I enjoy riding and on
clothes I find comfortable - why should I spoil it?

If you wish to change your statement to "For me, as a committed cyclist...",
then I'll have no argument with you. But you certainly don't speak for me.

clive

On Mon, 9 Aug 2004 21:52:06 +0100, Callas
wrote (more or less):

wrote:

[snip]

Very interesting read.

For us, as commited cyclists, I think the answer is: we already cycle,
and we're going to cycle pretty much no matter what, so wear the helmet.

Emm, did you read the article?

--
Cheers,
Euan
Gawnsoft: http://www.gawnsoft.co.sr
Symbian/Epoc wiki: http://html.dnsalias.net:1122
Smalltalk links (harvested from comp.lang.smalltalk) http://html.dnsalias.net/gawnsoft/smalltalk

Callas wrote:
wrote:

[snip]

Very interesting read.

For us, as commited cyclists, I think the answer is: we already cycle,
and we're going to cycle pretty much no matter what, so wear the
helmet.


Rubbish. If you want to wear one, fine. I don't.

FWIW, I was out on a short Audax the other week. Without helmet, I was
hearing things much further away than a helmetted colleague. Presumably
due to the wind rushing around the plastic. I was comfortably cool, he was
too hot.

A lesson there; make your own mind up and don't impose on others.



- Nigel
--
NC - Webmaster for http://www.2mm.org.uk/
Replies to newsgroup postings to the newsgroup please.

Callas wrote:

wrote:

[snip]

Very interesting read.

For us, as commited cyclists, I think the answer is: we already cycle,
and we're going to cycle pretty much no matter what, so wear the helmet.

For me, as a committed cyclist, I think the answer is: I already cycle,
and I'm going to cycle pretty much no matter what, so why wear the helmet?

schreef ...
Callas wrote:
wrote:

[snip]

Very interesting read.

For us, as commited cyclists, I think the answer is: we already cycle,
and we're going to cycle pretty much no matter what, so wear the
helmet.


Rubbish. If you want to wear one, fine. I don't.

FWIW, I was out on a short Audax the other week. Without helmet, I was
hearing things much further away than a helmetted colleague. Presumably
due to the wind rushing around the plastic. I was comfortably cool, he was
too hot.

A lesson there; make your own mind up and don't impose on others.

Very true.

And buying a well-vented helmet helps, too. I wear a Giro Helios on my -
almost bald - head. During the ascent of the Ballon d'Alsace, a few
weeks ago, I tried out the temperature difference between helmet-on and
helmet-off. For me - with my "exposed" top skin - there was hardly any
difference. My wife however who has a full head of beautiful hair does
find it clearly cooler without her helmet. She donned it again on the
descent :-)

--
Regards,
Marten

in message , Callas
') wrote:

wrote:

[snip]

Very interesting read.

For us, as commited cyclists, I think the answer is: we already cycle,
and we're going to cycle pretty much no matter what, so wear the
helmet.

I haven't yet read the article, because Guy's original post with the URL
presumably in hasn't yet reached me. But the reason *not* to wear a
helmet is that (unless the article has new evidence which refutes this)
helmet wearing is positively correlated with getting killed. No, I
don't know why, but I want to live a long and healthy life thank you
very much.

I'm not going to put my life in danger because of fashion or because
some busy-body politician somewhere wants to be seen to be doing
something.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

IMHO, there aren't enough committed Christians, but that's care
in the community for you. -- Ben Evans