advisor wanted

Rich wrote:
Tony Raven wrote:

In the US, in 1991 18% of cyclists wore helmets. There were 568,000
cyclist accidents requiring hospital treatment. 12% were head injuries.
By 2000, 30% of cyclists wore helmets. There were 627,160 cyclist
accidents. 12% were head injuries. So whatever all those extra
helmets were doing they were not reducing head injuries.

In the UK the proportion of female under-16 cyclists wearing helmets
is double that of males. The proportion female under 16 cyclists
suffering head injuries is virtually identical to that of males. So
whatever all those extra helmets are doing for the girls, they are not
protecting them from head injuries.

The country with the lowest head injury rate for cyclists is Holland.
They also have the lowest helmet wearing rate in the developed world
at 0.1%. Curiously the USA is the reverse with six times the death
rate per km cycled and a 38% helmet wearing rate.

In Australia where helmets are mandatory and enforced, one state has
repealed the helmet law. That state now has the highest cycling rate
and lowest head injury rate in Australia.

Very interesting information, and I'd like to read more. Can you post
links to the studies or web sites where you got them?

With pleasure.

The international definitions of the various types of injury classes are
given by the OECD in http://www.oecd.org/dataoecd/24/1/2103123.pdf

The US data comes from the CPSC National Electronic Injury Surveillance
System: http://www.cpsc.gov/library/neiss.html


The UK data comes from a paper that is well worth reading:

Accident Analysis & Prevention, Vol 37 pp807-815 http://snipurl.com/g10l


The Netherlands/US data comes from http://www.cyclehelmets.org/index.html


The Australian data is from "Australia Cycling; Bicycle Ownership, Use
and Demographics" July 2004 by the Australian Bicycle Council.

--
Tony

"I did make a mistake once - I thought I'd made a mistake but I hadn't"
Anon

Butch wrote:
Hi Peter, Sorry for the delay in response but the weather is so great
I have been out riding. I am sorry if I upset you so much, I suspect
you must be quite young to be so naive.

You didn't upset me, you were just being wrong. I'm 39 btw.

You don't seem to get the
point that when a helmet works the accident is not major and is not
reported.

And therefore that should contribute to a fall in serious head
injuries as helmet wearing rates increase. But no such thing
happens, so it looks like the supposition you've made is flawed.

For your information in our country Health care is so
expensive that most people seldom go to ER.

But this will still lead to reported serious accidents falling /if/
the helmets are reducing the need to get to ER. But is doesn't.

The man who landed on his head was taken in an ambulance, I seriously
doubt if anyone at the hospital took any data.

You think they don't record admissions? So where does all the data
there is come from?

As I suggested to Jim, "Show me the casualty savings!" What you've
said above in no way prevents effective helmets changuing the
numbers, but the numbers don't change.

You complained about how dubious relying on statistics is, yet
you've chosen to use a tiny sample base in your /own/ statistics,
so your own statistics are clearly flawed. Yet you choose to use
them rather than much sounder data sets with usable sample bases.
If you don't like statistics because they can be misused, stop
using bad data yourself.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

Helmets are kind of like tire pumps. Having a pump along for the ride won't
prevent p*nct*r*s, but if you get one, you'll be glad you had one with you.

I wonder if the insurance industry has good data about h*lm*ts and how they
figure into injury/treatment equation.
much snippage of 'your data are crap and my data are gold standard'



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gotbent wrote:
Helmets are kind of like tire pumps. Having a pump along for the ride won't
prevent p*nct*r*s, but if you get one, you'll be glad you had one with you.

I wonder if the insurance industry has good data about h*lm*ts and how they
figure into injury/treatment equation.

The problem with that sort of observational study is that it is a much
discredited way of assessing things and has led to some major medical
mistakes such as in MMR and HRT. For a critique have a look at
http://ije.oxfordjournals.org/cgi/content/full/33/3/464 and
http://bmj.bmjjournals.com/cgi/conte...l/329/7471/868

I don't know about elsewhere in the world but in the UK Courts, no
insurance company has succeeded with a contributory negligence claim in
personal head injury cases when the cyclist victim was not wearing a
helmet (and they have tried). Either they have the data and are not
using it, suggesting it does not help them, or they don't have it.

Someone closely involved in two of these cases has said:

"Referring back to the Court case mentioned early, the very eminent QC
under whose instruction I was privileged to work, tried repeatedly to
persuade the equally eminent neurosurgeons acting for either side, and
the technical expert, to state that one must be safer wearing a helmet
than without. All three refused to so do, stating that they had seen
severe brain damage and fatal injury both with and without cycle
helmets being worn. In their view, the performance of cycle helmets is
much too complex a subject for such a sweeping claim to be made."

and

"In a recent Court case, a respected materials specialist argued that a
cyclist who was brain injured from what was essentially a fall from
their cycle, without any real forward momentum, would not have had their
injuries reduced or prevented by a cycle helmet. This event involved
contact against a flat tarmac surface with an impact energy potential of
no more than 75 joules (his estimate, with which I was in full
agreement). The court found in favour of his argument."

Make of that what you will.

--
Tony

"The best way I know of to win an argument is to start by being in the
right."
- Lord Hailsham

gotbent wrote:
Helmets are kind of like tire pumps. Having a pump along for the
ride won't prevent p*nct*r*s, but if you get one, you'll be glad
you had one with you.

Up to a point... but the above implies if you're in an accident you
/will/ be better off with a helmet. But if that were the case then
we would expect to see a dent in the serious accident figures with
increasing helmet usage, but we don't.

What the mechanism underlying this lack of effect is we don't
really know. There are various suggested mechanisms but we don't
know to what extent they operate. But we do know the final outcome
of that operation appears to be no effect on serious injuries, so
we can't say with any confidence that if you have an accident with
potential to give serious head injuries that you will be better off
with a helmet than without. Read the quote from Brian Walker I
gave again (Tony has re-quoted it in the other followup to your post).

I'll grant you that it seems obvious you'd be better off with a
helmet, but just because common sense tells you that it doesn't
make it right. Common sense also says if they help we'll see an
effect on casualties, so with two bits of obvious common sense
we've got contradictions. Which tells us we can't simply rely on
common sense for the answers.

I wonder if the insurance industry has good data about h*lm*ts
and how they figure into injury/treatment equation

See Tony's reply for more on that.

much
snippage of 'your data are crap and my data are gold standard'

One or two anecdotes vs. the effective total sum of all anecdotes.
There really isn't much question as to which is the more useful
statistical starting point. If you want to argue that even so it
isn't "gold standard" I would agree, but it's still the best we've
got and a better thing to be working with than one or two people
assuring you a helmet saved their life.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

snippage

I'm one of the anecdotal cases. I crashed, broke my collar bone, and hit my
head hard enough for the foam along the temple line to compress more than
half its thickness. My eyeglasses cut a huge gash across the top of my nose.
Plenty of aches from my near 30 mph crash. No concussion or even a headache.
Did I do something stupid...yes succeeded in getting too much air jumping a
break in the road, and went into an oscillation when I landed. Did I do
something stupid because I was wearing a helmet? Probably not. Certainly it
was a testosterone induced wave of stupidity, as in those days I routinely
jumped railroad tracks without any problem. Man, I got some major air that
time though, and the back of the bike started to come around and I knew I
was ****ed big-time. So, I'm probably a data point flyer, but I know I'm
fallible and even if the stats are right, and I never have another head
impact gravity event, I'll still wear a helmet whenever I ride. I wish you
well too. Safe rides and all that.



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gotbent wrote:

I'm one of the anecdotal cases. snip

I don't doubt it. But there still isn't any reduction in overall
serious injuries from increased helmet wearing.

In the quote previously made eminent neurosurgeons said it was too
complex an issue to say that one was clearly better off with a
helmet than without, so it is entirely possible that in some cases
helmets can make things worse (have a google for "rotational
injuries" as a possible mechanism, in addition to more cases of
hitting one's head /at all/ due to an effectively bigger and
heavier head). You can't make any assumptions about a notional
next accident and if a hat will help, hinder, or do nothing, yet
that's what a lot of people are doing.

Given it is quite natural for people to assume a positive benefit
you won't hear anecdotes saying how they made things worse, but
remember that population level statistics of all serious injuries
include all the positive anecdotes, including those where an injury
has been removed from the serious bracket altogether, and despite
all these anecdotes things haven't improved.

I had my own anecdote which you can google out from uk.rec.cycling
where I was wearing a helmet and I was convinced it saved me a much
worse injury. Perhaps it did, but that is still no guarantee about
how a helmet will affect another accident I may have. The hard
numbers tell me my chances are no better or no worse whether or not
I wear one. It was /very/ difficult abandoning my helmet for
routine riding, but now I have I'm glad I did: I'm much more
comfortable and enjoy my cycling more, and there is no evidence,
/despite/ my previous anecdotal experience, that I am in any more
danger of a serious head injury.

See http://www.cyclehelmets.org/mf.html?1019 for more detail and
references.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

On Sun, 30 Oct 2005 07:19:29 -0700, Rich
said in :

Possible answers:
We're moving much slower while walking
We have seatbelts and airbags for driving
We also moving slower runnning then biking
We have banisters to hold onto while descending staircases

Interesting, then, how the proportion of head injuries for
hospitalised pedestrians and cyclists turns out to be almost exactly
the same (30.0% for cyclists, 30.1% for peds). And the dominant cause
of those injuries turns out to be something which vastly exceeds the
protective capacity of any available helmet, namely impact with motor
vehicles.

Guy
--
http://www.chapmancentral.co.uk

"To every complex problem there is a solution which is
simple, neat and wrong" - HL Mencken

In .com, on 10/30/05
at 05:23 AM, "rBOB" said:



Again, you are using apples to make statements about oranges and are clueless that you are doing it.

I'm agnostic on this issue and generally stay out of these discussions
but I wish you would stop writing this over and over. It is perfectly
legitimate to ask: Why has society deemed it appropriate / necessary /
mandatory to wear a helmet while cycling but not while walking, driving,
running, descending staircases, etc, etc...)?


Appples and oranges. If you can not see that, then there is no point
saying anything else.


jim

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On 30 Oct 2005 06:40:13 -0800, "Butch" said in
.com:

Hi Peter, Sorry for the delay in response but the weather is so great
I have been out riding. I am sorry if I upset you so much, I suspect
you must be quite young to be so naive. You don't seem to get the
point that when a helmet works the accident is not major and is not
reported.

And you don't seem to get the point that there is no known case where
cyclist injuries have reduced with increasing helmet use (but plenty
which show the opposite).

I am neither young nor naive. I have also read most of the research,
both ways. If you'd like to cite the study on which you base your
opinion?

Guy
--
http://www.chapmancentral.co.uk

"To every complex problem there is a solution which is
simple, neat and wrong" - HL Mencken