On Sun, 20 Jun 2004 17:14:41 -0400, Steven Bornfeld
<
[email protected]> wrote in message
<
[email protected]>:
>> One of the key factors in changing my view was the fact that I had no
>> idea the population level studies even existed. Helmet promoters were
>> telling me that helmets save 85% of head injuries and 88% of brain
>> injuries, stated as fact, but then I found that even the original
>> authors had revised these estimates downwards
>Well, this is a different issue. I am concerned with whether the
>safety studies are flawed. Intent is not an insignificant issue, but
>I'm not really concerned with that for the purposes of this discussion.
> Certainly if these studies were funded by the helmet manufacturers it
>casts things in a different light.
Anything with the Safe Kids logo is tainted by Bell sponsorship.
But that's not really the issue; the issue is that those who promote
helmets, don't admit that there is acontrary view. Over here
charities are not supposed to present one side of an argument as if it
were the only side, but the helmet charity do. Bell must be laghing
up their sleeve to see chairities raising money to do their sales work
for them using claims they cannot make because of laws on claims made
in advertising!
>> Actually the real position is probably that helmets prevent most
>> trivial injuries and very few serious ones. There is a probably
>> narrow band of cases where helmets may turn a serious injury ionto a
>> minor injury, but risk compensation also means that there is another
>> band of cases where the crash would not have happened in the first
>> place had the rider not been wearing a helmet.
>This is something that the anti-helmet partisans continue to repeat,
Who are the anti-helmet partisans? How many have you come across to
date? I've met maybe two people who are anti helmet. The balance are
sceptical or pro-helmet. Most pro-helmet soon become sceptical.
>and I'm not sure what you mean by this. I am inclined to think you're
>saying that folks feeling relatively protected will engage in riskier
>behavior. I think this is speculative; the same argument the right uses
>in this country to attack dispensing of condoms. I've seen plenty of
>risky behavior from both helmeted and non-helmeted riders. Of course
>this is anecdotal, but I doubt anyone would seriously contend that
>people drive more recklessly because they are wearing seat belts.
Here you are wrong: not only do people contend this, it is actually a
mainstream view. Taxi drivers in Germany and Denmark were found to
drive more aggressively in cars fitted with ABS. Drivers who did not
habitually wear seat belts were found to drive faster when persuaded
to wear seat belts. Seat belt legislation has never resulted ina
reduciton in road deaths, but it did lead to the biggest recorded
increase in pedestrian, cyclist and rear-seat passenger deaths in the
UK. The arrival in the second-hand market of the first generation of
cars with drivers' airbags has seen a sharp rise in fatalities of
front seat passengers of young male drivers.
A good book on the subject is Risk by John Adams.
>> I do have a problem with helmet promotion which igniores the
>> distinction between different kinds of crash and different kinds of
>> injury. The idea that because a helmet saves a cut head it will
>> necessarily prevent massive brain trauma when hit by a pseeding truck
>> is laughable, but by using a single figure for injury reductions that
>> is exactly what the promoters are trying to imply.
>I don't doubt that this is done; I personally don't know anyone that
>cycles who buys that position though.
If you repeatedly tell a 14-year-old that helmets prevent 85% of head
injuries and 88% of brain injuries, what will be the effect on their
riding?
>I think that safety measures in general should promote a healthy
>respect for the dangers implicit in any given activity.
But the dangers in cycling are low.
> I would view
>effective cycling instruction in the same way. For that matter, one
>must demonstrate competence before being licensed to drive a motor
>vehicle. In spite of this training many drive with a blatant disregard
>to the real dangers.
Because the danger is not to them, or at least they get all the
benefit of the aggressive driving and only part of the risk..
>I feel you are almost certainly right about effective cycling
>instruction being more important to safety. For that matter, at least
>here in the states a very large proportion of those wearing helmets wear
>them incorrectly. One wonders how different the population studies
>would be were riders fit properly with helmets.
Hard to say; since up to 96% of hemets are not worn correctly that
suggests the problem may be with the helmets not the wearers. I've
twice found people wearing the blessed things back to front!
>Another issue is cultural; in the UK, and in Europe and most of the
>rest of the world, the bicycle is seen as a legitimate means of
>transportation. In the U.S. it is overwhelmingly still seen as a toy.
>As a consequence of this, very few cyclists--even those who bicycle for
>legitimate transportation follow even basic transportation regulations.
A great reason to challenge that failing
> (As an aside, while on a bicycle tour I once rode through a red
>traffic signal in London--a transgression for which I was vigorously
>chastised by several pedestrians. I didn't do it again.)
Heh! Red lights are treated as "give way" by all comers, motorised
and cycling, in London
>I assume that
>the way increased cycling will improve safety is first that there are
>less motor vehicles on the road.
- drivers see more cyclists so are expecting them
- drivers are more likely to be cyclists and know how to behave around
them
>Furthermore, I would assume that once
>cycling reaches a certain critical mass it will have a political
>constituency to effect changes in access, motor vehicle regulations etc.
No, I don't think so. There's no money in it.
>> I have analysed
>> UK child hospital admissions returns and found that there is no
>> significant difference in the proportion of head injuries suffered by
>> road cyclists and pedestrians, despite helemt wearing rates only
>> around 15%.
>Again, I must ask if this pertains to total number of incidents,
>proportion of head injuries among total injuries, head injuries per unit
>time, etc. This is a complicated issue; I trust that you have looked at
>the design of the studies as apparently some of the journals have not.
That's why I stated the figures as I did. Cyclists admissions 49%
head injury, pedestrians 46% head injury, 15% helmet wearing rate.
So: cyclists and pedestrians suffer roughly the same proportion of
head injuries. The ratio is pretty much unchanged with helmet use.
By comparing the ratio you normlaise out exposure. You can do similar
calculations with severity ratios and show that the proportion of
cyclist inuries which are severe are unaffected by helmet use.
By contrast, Liddites claim "head injuries fell in Australia following
the law" which is literally true, but they fell by less than the fall
in the number of cyclists.
Look at graph 2 here:
http://agbu.une.edu.au/~drobinso/bhacc.htm
>Help me out here--this may be a UK expression--what is FUD? And why
>would you not be anti-helmet if the evidence is that they aren't useful
>in protecting against serious injury?
FUD is a very American expression: Fear, Uncertainty and Doubt
I am not anti helmet because I think they can prevent many
uncomfortable minor injuries. I am not against mountain bikers
wearing shin pads or elbow pads, or unicyclists wearing wrist guards.
I don't think these things should be mandated or even officially
promoted. They are there, use them if you want.
>> That, of course, is a fundamental problem. Any agnostic who argues
>> with a True Believer will end up sounding like an atheist, even though
>> they are not.
>This of course is true. But unlike religion, this one should be easy
>to determine if the will is there.
So it seems to me. When I read the balance of the evidence I
certainly came to that view
>> You're supposed to try to disprove, not prove, your
>> initial premise. In this case the researchers [...] decided on the
>> outcome before they started.
>Well, sure. That's the way it is supposed to be. But drug trials are
>not conducted by folks looking for the drugs not to work. Of course,
>one cannot do a double-blind study on this. But this is a very serious
>charge against the NEJM, and I would have expected to hear about it.
It's not a particularly serious charge against them, actually; it's a
study with an error in it. It happens all the time. It is an
indictmentof their peer review process, though. But not as bad as the
Cook & Sheikh paper in Injury Prevention.
>> Actuarial data relies on long-term trends and large data
>> sets. In this case it looks more like a kneejerk reaction to asingle
>> incident. As those who follow pro racing know only too well, the
>> mandatory use of helmets has not stopped racing cyclists from dying of
>> head injuries. The numbers are in any case too small for robust
>> statistical comparisons to be made.
>It was, IIRC, not based upon any one incident. The USOC had lost all
>of its liability coverage; the racing season was delayed while another
>policy could be found. This one was hammered out de novo.
The fact remains that it was probably due more to the prejudices of
the underwriter than any sound actuarial judgement.
>>>>Only about 10% of cyclist injuries are to the area covered by the
>>>>helmet and many (possibly most) cyclists who die of head injury also
>>>>have other mortal injuries. Most fatal cyclist injuries are of course
>>>>sustained in crashes involving motor vehicles: it is motor traffic,
>>>>not cycling, which is dangerous.
>Come on! That's a little like saying driving a car isn't
>dangerous--it's those darned OTHER drivers who keep crashing into me! ;-)
Not at all. Motor traffic is responsible for 10% of child hospital
admissions in the uk but 50% of fatalities. Offroad cycling accounts
for 90% of all cycling activity but only half of hospital admissions.
Cars are dangerous to others in a way that bikes are not.
> Well, as you say, there's cycling, and then there's cycling. I made a
>decision after a serious crash in my first year racing that I was
>finished. It's a bargain you make with yourself--I won't race again and
> THEN I'll be safe. I was not spared a head injury by my helmet, but I
>probably saved myself having my eyes cut up by the broken glass I fell into.
Sure. I don't do technical downhill - too risky. I fact the kind of
riding I do it's very unlikely a helmet would ever be of benefit, not
least because I ride with my **** a foot off the ground
>Now, this is likewise the kind of statistic that bothers me. I am
>assuming that you are speaking of cardiovascular risk. OK. But the
>choice should not be cycling vs. couch potato. I have never seen a
>study actually pretend to predict life extension based on a particular
>volume of cardiovascular exercise anyway. However, for those who cycle
>for fitness instead of purely for transportation (as I do) one cannot
>assume that someone who stops cycling will do no other aerobic exercise.
> There are other confounding factors, such as that those who bicycle or
>do other forms of aerobic exercise are less likely to smoke. I have
>seen studies that attempt to correct for this, but they are mostly fantasy.
Sure - but the message is sound. Cyclists live longer than average;
this would not be possible if cycling were extraordinarily dangerous.
>> These are the proportions of all admissions which are due to head
>> injury. So, if you have a bike crash, you are not markedly more
>> likely to suffer head injury than if you are hit as a pedestrian.
> This assumes that the total number of person-hours spent cycling is
>roughly equivalent to the total number of person-hours spent as a
>pedestrian.
No it doesn't, because it compares like with like. You have already
been injured: is your injury more likely to be a head injury if you
are a cyclist? Answer, not really. Are you more likely to be injured
per se as a cyclist? Probably not, inless there is a motor vehicle
involved.
>> The risk levels comparison: 10% of cycling is on road, 90% off road.
> This is a simply amazing statistic. In the U.S. even most mountain
>bikes are never ridden off road.
Includes bike paths and trails. You might be surprised
>So what would you change? As you've pointed out, cars are heavily
>regulated because of the greater danger. The industry is more powerful
>economically and politically. So what would be the focus of improving
>bicycle safety vis a vis automobiles?
First, enforce traffic regulations (for all road users) inna zero
tolerance stylee. Second,make sure that quality bike training is
available for all. And third, make sure that anybody who drives badly
gets a chance to find out how the other half live as they do without
their license for a while.
> Thanks for your interesting and thorough discussion. This is obviously
>an important issue for you. The issue of helmet mandates is frankly
>unimportant to me. What is important is the truth regarding helmets and
>bicycle safety, for myself and my family. As someone who has been
>permanently injured in crashes I'm sure it is something on which we both
>can agree
It is a matter of life and death, literally. I spend between one and
two hours every weekday riding my bike on the roads, and I have kids.
I cannot afford not to take an interest
