Re: Helmet Poll: First Hand Experience

[Tony Raven]

Mark Hickey wrote:
> Tony Raven <[email protected]> wrote:
>
>> You know wrong then. All the studies show the head injury risk
>> increases when helmets are mandated (and enforced). Go and read the
>> work of Robinson and others that have studied this in detail.
>
> All the studies show that as actual driving speeds have gone up over
> the years, fewer people are getting killed on the roads per mile
> driven. Hence, I propose to outlaw speed limits because they
> obviously make our roads less safe.
>
> Silly? Yes. Realistic? No.
>

Mark takes the opportunity to show that he does not understand
epidemiology and the difference between correlation and causation. As
Robinson has recently pointed out in the BMJ, there is a much greater
correlation between electricity prices and cyclist head injuries than
there is between helmet use and cyclist head injuries but that does not
mean putting up electricity prices will reduce head injuries. You need
to go beyond correlation to show causation and most of the helmet
population studies have done that to a greater or lesser extent.

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

 

[Michael Press]

In article <[email protected]>,
Tony Raven <[email protected]> wrote:

> Michael Press wrote:
> >
> > You entered this discussion when I excoriated physicians
> > who diagnose with BMI. You posted a URL to a CDC article
> > on BMI that turns out to say exactly what I say about the
> > utility of BMI. Is it OK with you to be diagnosed via BMI?
> > It is not with me.
> >
>
> I think you will find that you entered a discussion between Java Man
> (who first raised it in urc post 2032)

And where did the aboriginal discussion begin? I replied
to the BMI question, EM replied to me and I replied to
him. You then took exception to my view on BMI.

> and myself on BMI as a suggested
> example of misuse of population statistics.
> http://makeashorterlink.com/?Q25265B4D

The use of BMI as a diagnostic tool is a misuse of
population statistics.

> You keep using the word "diagnosed". I have repeatedly called it cheap
> and cheerful indicator of whether further investigation is needed. Your
> BMI is bang in the middle of the normal range so there is no need to
> look further as to whether you might be under or over tall. If it was
> 30 then the physician should be considering whether you are undertall
> and need to grow a bit. Part of that consideration is your build, age,
> sex, race and how much exercise you take - Sumo wrestlers have
> horrendous BMIs but are very very fit. Much of that consideration can
> be done by observation and questioning without going to the complex and
> expensive diagnostics. And at the end of the day a wrong diagnosis is
> unlikely to be harmful and most people don't succeed in following the
> advice anyway.

People are not so stupid that somewhere inside, often
unreachable, they do not know they are being lied to. When
a physician uses BMI for diagnoses he is lying; and I have
been saying this from the start.

> It is OK with me to use BMI as part of a diagnosis. Is it with you?

I don't know and no.

You provided a URL: ` Have a look at the CDC site for a
primer on BMI.'
<http://www.cdc.gov/nccdphp/dnpa/bmi/adult_BMI/about_adult_
BMI.htm>

to support your view. That primer reads

`BMI is not a diagnostic tool.'

Exactly what I said at the start that you took exception
to.

--
Michael Press

 

[Tony Raven]

Michael Press wrote on 18/06/2006 10:45 +0100:


> And where did the aboriginal discussion begin? I replied
> to the BMI question, EM replied to me and I replied to
> him. You then took exception to my view on BMI.

I suggest you use Google Groups to revisit it. Your first post on the
subject starts with a quote from a message from Java Man replying to one
of my posts replying to him about BMI. A minor point I know but you
joined in, as is the nature of Usenet, in an exchange between me and JM
not the other way round.


>
> Exactly what I said at the start that you took exception
> to.
>

Where on earth did you get that from? Lets look at the key sentences of
the your post and my reply:

You: I would drop any examining physician who
You: diagnosed me, even in part, by way of BMI.

Me: I wouldn't. Its a cheap and cheerful indicator, no more.

Take exception? I don't think so Tim.

It seems that CDC and a whole range of other medical bodies are quite
happy to suggest that physicians use BMI as a screening tool (the bit
you missed out). But would drop any physician that used it. Or are you
saying you are happy for them to use it as a screening tool (aka
"indicator")

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

 

[Chris Malcolm]

In uk.rec.cycling G.T. <[email protected]> wrote:
> [email protected] wrote:
>> Paul Murphy wrote:
>>
>>
>>>I haven't been convinced by those opposing Sorni.
>>
>>
>> I note that those opposing Sorni have repeatedly advocated actually
>> reading the research on this issue. Sorni, of course, has refused.
>> I'm curious - how much of the research have you read?
>>
>> Over time, there's been a strong tendency for those who actually learn
>> about this issue to change from a pro-helmet to a helmet-skeptic
>> stance. It happened to me. I understand it happened to Guy. And to
>> many others.
>>

> It happened to me. Check some of my posts on r.b.r., r.b.t., or
> r.b.o-r. towards the end of the last century.

As someone who had been cycling accident-free for general transport
purposes for decades before cycling helmets were invented, I was
sceptical of the general idea that cycling was dangerous enough to
warrant bothering to spend money reducing such a small risk. But given
the heated debates that the topic provoked, I decided I ought to try
to take a rational decision about whether or not to use one.

I decided in the end that it *was* worth bothering to reduce my risks
of brain injury, but the more I looked into the evidence the more it
looked as though for cycling alongside cars etc. the current design of
helmets were at best no use, and quite possibly increased the risks. I
was also distinctly unimpressed, to put it mildly, to discover that
the standards of protection of cycle helmets had actually been
*reduced* because helmet manufacturers thought that selling less
protective helments would increase their profits.

I looked into the research on accident injury and speeds, carried out
a few personal experiments, and decided that my risks of injury
increased dramatically at speeds above about 20mph due to a combination
of the speed of my own protective reflexes and the force of the
impact.

So I concluded that until someone actually bothered to do the research
necessary to produce a helmet that actually worked, as opposed to one
that appealed to the commonsense of the uneducated, I'd limit my
bicycle speeds to less than 20mph. It makes surprisingly little
difference to my usual journey times, possibly because I'm an aged
potterer who doesn't wear special cycling clothes, what I believe
young Americans consider "Not a Real Cyclist".

I do miss those exhilirating fast downhill descents :-(. If ever
someone produces a helmet for road cycling which works, I'll be
definitely interested.

--
Chris Malcolm [email protected] +44 (0)131 651 3445 DoD #205
IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
[http://www.dai.ed.ac.uk/homes/cam/]

 

[Helen Deborah Vecht]

Michael Press <[email protected]>typed

> 1.75 m
> 68 kg

> My adult height and weight. I have had sedentary
> occupations and on my feet all day carrying and working
> tools. In my opinion nobody is obese until they waddle.

Your BMI is <25 anyway. What *is* the issue?

BMI is a very crude tool anyway IME.

Dr Raven of this parish would exceed 25 long before he looked remotely
plump, just cos he's tall.

I have a BMI of 25 and look 'borderline'.

Someone of <1.5m with a BMI of >25 looks *fat*.

Our weight varies as the cube of our height; having a ratio dependent on
its square happens conveniently to work for a small range of adult
heights. It is useless for children.

--
Helen D. Vecht: [email protected]
Edgware.

 

[Helen Deborah Vecht]

Tony Raven <[email protected]>typed


> Michael Press wrote:
> >
> > 1.75 m
> > 68 kg
> > My adult height and weight. I have had sedentary
> > occupations and on my feet all day carrying and working
> > tools. In my opinion nobody is obese until they waddle.
> >

> And you are not being right in the middle of the "normal" range for BMI.

Michael Press *is* slap bang in the middle of the normal range. Very
convenient for buying clothes...

--
Helen D. Vecht: [email protected]
Edgware.

 

[Michael Press]

In article <[email protected]>,
Tony Raven <[email protected]> wrote:

> Michael Press wrote on 18/06/2006 10:45 +0100:
>
>
> > And where did the aboriginal discussion begin? I replied
> > to the BMI question, EM replied to me and I replied to
> > him. You then took exception to my view on BMI.
>
> I suggest you use Google Groups to revisit it. Your first post on the
> subject starts with a quote from a message from Java Man replying to one
> of my posts replying to him about BMI. A minor point I know but you
> joined in, as is the nature of Usenet, in an exchange between me and JM
> not the other way round.
>
>
> >
> > Exactly what I said at the start that you took exception
> > to.
> >
>
> Where on earth did you get that from? Lets look at the key sentences of
> the your post and my reply:
>
> You: I would drop any examining physician who
> You: diagnosed me, even in part, by way of BMI.
>
> Me: I wouldn't. Its a cheap and cheerful indicator, no more.
>
> Take exception? I don't think so Tim.
>
> It seems that CDC and a whole range of other medical bodies are quite
> happy to suggest that physicians use BMI as a screening tool (the bit
> you missed out). But would drop any physician that used it. Or are you
> saying you are happy for them to use it as a screening tool (aka
> "indicator")

It is a tool for assessing populations. Using it to assess
an individual is the slippery slope. The physician
unconciously begins to use it as a diagnostic tool.

When the patient is in front of the physician, why would
the physician be thinking about BMI? It can only mislead
him. The patient may have a higher than `normal' BMI. Sure
he is carrying some flab, but underneath may be heavily
muscled. A physician who treats BMI as a diagnostic tool
can easily mislead himself.

EM related how a physician misdiagnosed him via BMI.

--
Michael Press

 

[Michael Press]

In article <[email protected]>,
Helen Deborah Vecht <[email protected]> wrote:

> Michael Press <[email protected]>typed
>
> > 1.75 m
> > 68 kg
>
> > My adult height and weight. I have had sedentary
> > occupations and on my feet all day carrying and working
> > tools. In my opinion nobody is obese until they waddle.
>
> Your BMI is <25 anyway. What *is* the issue?

Misuse of a population assessing index as a diagnostic
tool. I stated that I would drop a physician who used BMI
as a diagnostic tool. Of course my weight is not a
problem; but I pay close attention to what physicians say
to me and how they think about things.

> BMI is a very crude tool anyway IME.

It is not a diagnostic tool. It is an effective tool for
assessing populations. I think the `waddle' test is a good
diagnostic tool.

> Dr Raven of this parish would exceed 25 long before he looked remotely
> plump, just cos he's tall.
>
> I have a BMI of 25 and look 'borderline'.
>
> Someone of <1.5m with a BMI of >25 looks *fat*.
>
> Our weight varies as the cube of our height; having a ratio dependent on
> its square happens conveniently to work for a small range of adult
> heights. It is useless for children.

--
Michael Press

 

[[email protected]]

Michael Press wrote:
> In article <[email protected]>,
> Tony Raven <[email protected]> wrote:
>
> > Michael Press wrote on 18/06/2006 10:45 +0100:
> >
> >
> > > And where did the aboriginal discussion begin? I replied
> > > to the BMI question, EM replied to me and I replied to
> > > him. You then took exception to my view on BMI.
> >
> > I suggest you use Google Groups to revisit it. Your first post on the
> > subject starts with a quote from a message from Java Man replying to one
> > of my posts replying to him about BMI. A minor point I know but you
> > joined in, as is the nature of Usenet, in an exchange between me and JM
> > not the other way round.
> >
> >
> > >
> > > Exactly what I said at the start that you took exception
> > > to.
> > >
> >
> > Where on earth did you get that from? Lets look at the key sentences of
> > the your post and my reply:
> >
> > You: I would drop any examining physician who
> > You: diagnosed me, even in part, by way of BMI.
> >
> > Me: I wouldn't. Its a cheap and cheerful indicator, no more.
> >
> > Take exception? I don't think so Tim.
> >
> > It seems that CDC and a whole range of other medical bodies are quite
> > happy to suggest that physicians use BMI as a screening tool (the bit
> > you missed out). But would drop any physician that used it. Or are you
> > saying you are happy for them to use it as a screening tool (aka
> > "indicator")
>
> It is a tool for assessing populations. Using it to assess
> an individual is the slippery slope.

Oh, I see, it's just the same as the helmet situation, eh?

Thanks for sharing!

(Watch the AHZs dance!)

 

[[email protected]]

Michael Press wrote:
>
>>What *is* the issue?
>
> Misuse of a population assessing index as a diagnostic
> tool.

Irony, thy name is" URC Anti-Helmet Zealot"!

 

[Just zis Guy, you know?]

On Sun, 18 Jun 2006 13:53:46 +0100, Helen Deborah Vecht
<[email protected]> said in
<[email protected]>:

>Dr Raven of this parish would exceed 25 long before he looked remotely
>plump, just cos he's tall.

My BMI is about 25.5. I could do with losing a few lb, maybe half a
stone, but fat? I think not.

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

85% of helmet statistics are made up, 69% of them at CHS, Puget Sound

 

[Just zis Guy, you know?]

On Sat, 17 Jun 2006 23:53:43 GMT, "Sorni"
<[email protected]> said in
<[email protected]>:

>>>>> It's merely your opinion that I stated as fact my opinion that my
>>>>> opinion is as valid as your opinion which in your opinion is based
>>>>> on fact but which is in fact itself merely an opinion.
>
>>>> An opinion based on the evidence, though.
>
>>> He opined.
>
>> Stated, actually.
>
>Actually stated his opinion. Exactly right. Glad you finally got it.

Close. Stated a fact.

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

85% of helmet statistics are made up, 69% of them at CHS, Puget Sound

 

[Tony Raven]

Michael Press wrote on 18/06/2006 21:11 +0100:
>
> When the patient is in front of the physician, why would
> the physician be thinking about BMI?

Physicians have been used actuarial derived weight-height tables for
years. BMI is just an alternative to them.

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

 

[Sorni]

Just zis Guy, you know? wrote:
> On Sat, 17 Jun 2006 23:53:43 GMT, "Sorni"
> <[email protected]> said in
> <[email protected]>:
>
>>>>>> It's merely your opinion that I stated as fact my opinion that my
>>>>>> opinion is as valid as your opinion which in your opinion is
>>>>>> based on fact but which is in fact itself merely an opinion.
>>
>>>>> An opinion based on the evidence, though.
>>
>>>> He opined.
>>
>>> Stated, actually.
>>
>> Actually stated his opinion. Exactly right. Glad you finally got
>> it.
>
> Close. Stated a fact.

I've no doubt you think that's true.

More's the pity.

 

[Helen Deborah Vecht]

"Just zis Guy, you know?" <[email protected]>typed


> On Sun, 18 Jun 2006 13:53:46 +0100, Helen Deborah Vecht
> <[email protected]> said in
> <[email protected]>:

> >Dr Raven of this parish would exceed 25 long before he looked remotely
> >plump, just cos he's tall.

> My BMI is about 25.5. I could do with losing a few lb, maybe half a
> stone, but fat? I think not.

You are tall (but not as tall as Dr Raven).

Unless you have ballooned since I saw you a year ago, I wouldn't class
you as fat either.

--
Helen D. Vecht: [email protected]
Edgware.

 

[Espressopithecus (Java Man)]

In article <[email protected]>, [email protected]
says...
> Espressopithecus (Java Man) wrote:
> >
> > My former doctor cautioned me about my BMI and advised me to lose weight
> > to get it into the low risk range in 1978. I addressed that [with the
> > phrase "Several decades ago . . . "] in my original question to you.
> >
>
> As I said it's been around since the mid 1800's although it would have
> been very unusual to use BMI in 1978 instead of the MLIC or NHANES
> weight for height tables.
>
> So knowledge has developed since then but was the advice to lose a bit
> of weight actually harmful?
>
I doubt that it would have been harmful to take the advice, but it would
have required me to cut back on exercise. I thought it was faulty
advice. So I chose to continue with my "risky" BMI despite my doctor
suggesting that my BMI exposed me to increased risk of cardiovascular
disease.

Population studies include people of all shapes, ages, sizes, risk
propensities, etc, and doing what the averages suggest is "best" may
not, in fact, be best for every individual in the population. I think
the BMI illustration was one of those cases, and my point in bringing
this into the discussion was to illustrate that in the absence of more
detailed data, it may be rational to choose a course of action that is
different from that suggested by the gross population data.

Rick

 

[Tony Raven]

Helen Deborah Vecht wrote on 19/06/2006 00:24 +0100:
>
> You are tall (but not as tall as Dr Raven).
>
> Unless you have ballooned since I saw you a year ago, I wouldn't class
> you as fat either.
>

Careful there Helen, if Michael has a problem with doctors using BMI
he'll have even more of a problem with you diagnosing Guy and I using
the HDVI ;-)

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

 

[Michael Press]

In article
<[email protected]>,
Espressopithecus (Java Man)
<[email protected]> wrote:

> In article <[email protected]>, [email protected]
> says...
> > Espressopithecus (Java Man) wrote:
> > >
> > > My former doctor cautioned me about my BMI and advised me to lose weight
> > > to get it into the low risk range in 1978. I addressed that [with the
> > > phrase "Several decades ago . . . "] in my original question to you.
> > >
> >
> > As I said it's been around since the mid 1800's although it would have
> > been very unusual to use BMI in 1978 instead of the MLIC or NHANES
> > weight for height tables.
> >
> > So knowledge has developed since then but was the advice to lose a bit
> > of weight actually harmful?
> >
> I doubt that it would have been harmful to take the advice, but it would
> have required me to cut back on exercise. I thought it was faulty
> advice. So I chose to continue with my "risky" BMI despite my doctor
> suggesting that my BMI exposed me to increased risk of cardiovascular
> disease.
>
> Population studies include people of all shapes, ages, sizes, risk
> propensities, etc, and doing what the averages suggest is "best" may
> not, in fact, be best for every individual in the population. I think
> the BMI illustration was one of those cases, and my point in bringing
> this into the discussion was to illustrate that in the absence of more
> detailed data, it may be rational to choose a course of action that is
> different from that suggested by the gross population data.

The physician has better data than BMI. He has you in
front of him.

While better data on bicycle helmets would be good, what
data we have shows no benefit in general; and therefore no
support for helmet laws.

No benefit in general means that almost everyone accrues
no benefit.

OR

Many accrue benefit, and many accrue risk from a helmet,
so that the documented averages come out right.

So supposing the second (more unlikely) condition obtains
you may actually accrue risk by strapping on a helmet!

Until the data is available what will you do?

--
Michael Press

 

[Sorni]

Tony Raven wrote:
> Helen Deborah Vecht wrote on 19/06/2006 00:24 +0100:
>>
>> You are tall (but not as tall as Dr Raven).
>>
>> Unless you have ballooned since I saw you a year ago, I wouldn't
>> class you as fat either.
>>
>
> Careful there Helen, if Michael has a problem with doctors using BMI
> he'll have even more of a problem with you diagnosing Guy and I using
> the HDVI ;-)

Nice grammar.

 

[Helen Deborah Vecht]

"Sorni" <[email protected]>typed


> Tony Raven wrote:
> > Helen Deborah Vecht wrote on 19/06/2006 00:24 +0100:
> >>
> >> You are tall (but not as tall as Dr Raven).
> >>
> >> Unless you have ballooned since I saw you a year ago, I wouldn't
> >> class you as fat either.
> >>
> >
> > Careful there Helen, if Michael has a problem with doctors using BMI
> > he'll have even more of a problem with you diagnosing Guy and I using
> > the HDVI ;-)

> Nice grammar.

Verbless fragment, meaningless waffle
Context-free quote
Usenet haiku

--
Helen D. Vecht: [email protected]
Edgware.