Advice on Helmets, again (was price vs quality)

For all discussions about this "lively" subject. All topics that are substantially about helmet usage will be moved here.
Jdsk
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Re: Advice on Helmets prices vs quality ????

Post by Jdsk »

Jdsk wrote:
Steady rider wrote:https://bmjopensem.bmj.com/content/bmjosem/6/1/e000746.full.pdf
Taking another look at this recent paper, 28 cases, 20 had previous concussions. Bicycling-related concussions leading to postconcussion syndrome in adults’, details ‘The mean duration of PCS for helmet wearers was 22.9 months, and 16.8 months for patients not wearing a helmet at the time of concussion (p=0.41)’

You've now quoted that twice. What do you think that p value means, please?

Would you like me to answer for you?

Thanks

Jonathan
ymfb
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Location: Salisbury

Re: Advice on Helmets prices vs quality ????

Post by ymfb »

[XAP]Bob wrote:
ymfb wrote:Despite all the rhetoric, I have a friend who had a low speed spill when another cyclist bumped into her, the Paramedic and A & E consultant both said her helmet saved her from catastrophic brain injury. No further proof needed for normal thinking people.


Plenty is needed by anyone who actually thinks about it - because a low speed spill is fundamentally no different from falling over when walking or running, and the rate at which *that* causes catastrophic brain injury is so low as to be ignored.
Additionally there is no obvious mechanism by which a few ounces of primarily expanded polystyrene could possible convert a "catastrophic" brain injury into what I can only guess was a minor concussion at worst.

That's part of the problem "normal thinking" is not to think at all.


I do not agree with your assessment, risk assessments are based on risk, likelihood and outcome, cycling is by any measure more dangerous than walking. Therefore to mitigate the likely injury some people wear safety equipment such as gloves and helmets, they (a) thought about it (b) did something. In my friends incident albeit at slow speed they had been riding faster and the other cyclist lost concentration when the speed was reduced. If you bang your head it hurts, if the impact is great enough you will damage something that maybe irreparable, if you break a limb it hurts, but it’s very likely repaired with a simple procedure and a few weeks discomfort.

I played cricket for many years, I never forgot to wear a ‘box’ and I was lucky enough to not get hit there, but I saw someone at the none strikers end carted off to hospital for surgery to put some parts of his anatomy back in the right order. He was at such a low risk he admitted he rarely wore a box before the accident, he certainly did afterwards. I didn’t wear a helmet at cricket as playing village cricket on soft strips the ball rarely pitched above knee height, but I never questioned or criticised them for doing so.

If you can find scientific evidence that shows helmets are dangerous or increase the severity of injuries by wearing them I’d be very surprised. RoSPA state “ A review of research showed the large protective effect of helmets. The review suggested that helmets decreased the risk of injury to the head and the brain by 65%-88% and the upper and mid-face by 65%. However, the review did acknowledge that little to no protection is offered to the lower face and jaw.“

I’m happy to accept RoSPAs advice.
Two wheels preferred.
Steady rider
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Re: Advice on Helmets prices vs quality ????

Post by Steady rider »

Jonathan
I am more interested in seeing how the 0.41 p value was calculated, it could be helpful if you can provide the calculation.


Thanks
Mike Sales
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Re: Advice on Helmets prices vs quality ????

Post by Mike Sales »

ymfb wrote:I’m happy to accept RoSPAs advice.



ROSPA is a front to divert criticism of motorist supremacy.
I'd recommend reading the conclusions of Winton Professor for the public understanding of risk, in the editorial he wrote for the British Medical Journal with Ben Goldacre, of Bad Science fame.

https://www.badscience.net/wp-content/uploads/Screenshot-2013-12-13-17.12.05.png
It's the same the whole world over
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
Steady rider
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Re: Advice on Helmets prices vs quality ????

Post by Steady rider »

Rospa quotes
A Cochrane Review found that five case-control studies from different countries showed the large protective
effect of helmets. The review suggested that helmets decreased the risk of injury to the head and the brain by
65%-88% and the upper and mid-face by 65%14. However, the review did acknowledge that little to no
protection is offered to the lower face and jaw15


https://www.cyclehelmets.org/1243.html
Zeegers T, Overestimation of the effectiveness of the bicycle helmet by the use of odds ratios’ http://www.fietsberaad.nl/?lang=nl&repo ... dds+ratios


May need to look up report by Zeegers
and
https://www.researchgate.net/publicatio ... jury_rates
Complimentary evidence
Recent studies have also cast doubt on the reliability of published case control studies and meta-analyses regarding the effectiveness of bicycle helmets. Zeegers 2015 states that “Three cases could be found in the literature with sufficient data to assess both risk ratios and odds ratios: the Netherlands, Victoria (Australia) and Seattle (U.S.A). In all three cases, the problem of overestimation of the effectiveness of the helmet by using odds ratios did occur. The effect ranges from small (+ 8 %) to extremely large (> + 400 %). Contrary to the original claim of these studies, in two out of three cases the risk of getting a head injury proved not to be lower for helmeted cyclists. Moreover, in all three cases the risk of getting a non-head injury proved to be higher for cyclists with a helmet.”

The Seattle study, Thompson et al claimed, “The use of helmets can reduce the risk of head injury by 85%”. The 400% overestimation from the Seattle study shows the degree of error that can occur from using comparisons and odds ratio calculations.

https://www.cyclinguk.org/campaigning/v ... le-helmets
In any case, there are serious doubts about the effectiveness of helmets. They are, and can only be, designed to withstand minor knocks and falls, not serious traffic collisions. Some evidence suggests they may in fact increase the risk of cyclists having falls or collisions in the first place, or suffering neck injuries.
Mike Sales
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Re: Advice on Helmets prices vs quality ????

Post by Mike Sales »

ymfb wrote:If you can find scientific evidence that shows helmets are dangerous or increase the severity of injuries by wearing them I’d be very surprised. RoSPA state “ A review of research showed the large protective effect of helmets. The review suggested that helmets decreased the risk of injury to the head and the brain by 65%-88% and the upper and mid-face by 65%. However, the review did acknowledge that little to no protection is offered to the lower face and jaw.“

I’m happy to accept RoSPAs advice.



This sounds like a reference to the Cochrane Review, in which 4 of the 7 paoers reviewed were by the reviewers.
Here is further criticism.

This report is cited by the UK Department for Transport as providing 'considerable scientific evidence' of the effectiveness of cycle helmets, and the justification for controversial helmet promotion policies.

Independent analysts, however, have criticised it strongly, as much for what it omits as what it contains. The review is highly selective in the evidence considered, makes no reference at all to so much that is crucially relevant, and does not show in any way how its conclusions follow from the evidence that is presented.

Key criticisms include:

The Review examined only one type of evidence on helmet effectiveness, that provided by non-randomised case-control studies.
There is no reference at all to traffic casualty trends, hospital admission data or any other large population evidence where helmet use is significant, even though most of this evidence shows no benefit from helmet use.
There is no reference at all to evidence that helmet use has often been associated with increased risk of injury or injury severity.
There is no reference at all to rotational injuries, the principal cause of serious head injuries. There is no mention of medical evidence that helmets may increase the likelihood of the most serious injuries.
Consideration of 'risk compensation', which can result in people taking more risks when helmeted and for which there is clear evidence, is specifically excluded from the Review.
There is no reference to cost-benefit analyses of helmet promotion.
There is no reference to other evidence unsupportive of helmet use, except to a minimal extent in a section on 'opinion pieces', which attempts to belittle helmet sceptic views without any consideration of the merits of evidence put forward.
Two data sets account for almost one-half of the total number of cyclists on whom the Review as a whole is based. Both are from the same team of researchers whose work has been widely criticised as extreme and untenable. Other case studies chosen for review have also been the subject of much criticism.
The Review itself identifies many serious criticisms of the studies examined, but no reasons are given as to why these were not reflected in the Review's conclusions.
Papers examined by the Review are sometimes reported selectively. For example, an Australian report is cited out of context as evidence for head injury reductions through helmet legislation, whereas the principal outcome that legislation was not cost-effective is not mentioned.
Helmet promotion campaigns are examined without any consideration of their impact on injury trends or cycle use, even though some of the papers examined suggest negative results.
Data on helmet legislation in Australia is seriously misrepresented.
The Review exaggerates cycling as being inherently hazardous, with no comparison to other everyday activities.
The impact of helmet promotion on wider public health goals is not assessed. There is no evaluation of the net benefit of less cycling with helmets against more cycling without helmets.
It's the same the whole world over
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
Jdsk
Posts: 24835
Joined: 5 Mar 2019, 5:42pm

Re: Advice on Helmets prices vs quality ????

Post by Jdsk »

Steady rider wrote:Rospa quotes
A Cochrane Review found that five case-control studies from different countries showed the large protective
effect of helmets. The review suggested that helmets decreased the risk of injury to the head and the brain by
65%-88% and the upper and mid-face by 65%14. However, the review did acknowledge that little to no
protection is offered to the lower face and jaw15
https://www.cyclehelmets.org/1243.html
Zeegers T, Overestimation of the effectiveness of the bicycle helmet by the use of odds ratios’ http://www.fietsberaad.nl/?lang=nl&repo ... dds+ratios


May need to look up report by Zeegers
and
https://www.researchgate.net/publicatio ... jury_rates
The Cochrane Review from 1999 under discussion;
https://www.cochranelibrary.com/cdsr/do ... s%7Chelmet

https://www.cyclehelmets.org/1243.html
is an unpublished and not peer reviewed "Commentary" on an archive of a no-longer maintained campaigning website.

https://www.researchgate.net/publicatio ... jury_rates
The paper is a report of conference proceedings and TTBOMK has not been accepted for publication elsewhere or peer reviewed. And it wasn't part of the Main Conference:
https://nationalroadsafetyconference.or ... he-fringe/

Jonathan
Jdsk
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Re: Advice on Helmets prices vs quality ????

Post by Jdsk »

As always I'd advise everyone to reread Goldacre and Spiegelhalter on the limits of our knowledge before and after turning to single studies.

Here are two much more recent analyses than that Cochrane Review:

"Bicycle injuries and helmet use: a systematic review and meta-analysis"
Olivier J and Creighton P
https://academic.oup.com/ije/article/46/1/278/2617198

"Bicycle helmets – To wear or not to wear? A meta-analyses of the effects of bicycle helmets on injuries"
Høye A
https://www.sciencedirect.com/science/article/pii/S0001457518301301?via%3Dihub

Jonathan
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mjr
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Re: Advice on Helmets prices vs quality ????

Post by mjr »

Jdsk wrote:As always I'd advise everyone to reread Goldacre and Spiegelhalter on the limits of our knowledge before and after turning to single studies.

Here are two much more recent analyses than that Cochrane Review:

"Bicycle injuries and helmet use: a systematic review and meta-analysis"
Olivier J and Creighton P
https://academic.oup.com/ije/article/46/1/278/2617198

Olivier J is a far more notorious campaigner than Clarke C who you refuse to [edit:] allow to be cited unchallenged, so let's apply the same rule there?

I don't recall reading the other reference before.
Last edited by mjr on 31 Mar 2021, 4:42pm, edited 1 time in total.
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mjr
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Re: Advice on Helmets prices vs quality ????

Post by mjr »

ymfb wrote:I do not agree with your assessment, risk assessments are based on risk, likelihood and outcome, cycling is by any measure more dangerous than walking.

Prove it?

Therefore to mitigate the likely injury some people wear safety equipment such as gloves and helmets, they (a) thought about it (b) did something.

But have they done something useful? Or is it the old fallacy "something must be done! Helmet use is something! Therefore helmets must be used!"

In your example, it was a collision, which helmet makers specifically warn their products are not designed or tested for. Any benefit they derived from the helmet should probably be written off as luck, because it could almost as easily ended up in a negative effect.

If you bang your head it hurts, if the impact is great enough you will damage something that maybe irreparable, if you break a limb it hurts, but it’s very likely repaired with a simple procedure and a few weeks discomfort.

Yeah, but no amount of plastic foam on your head will protect your other vital organs and damage to those could be irreparable and that's a far more common cause of cyclist deaths. It's far better to try to reduce collisions than try to mitigate only one of the effects with a product whose makers say is not designed to be effective in that scenario!

I’m happy to accept RoSPAs advice.

RoSPA's mission would still be completed if cycling "accidents" were reduced by stopping everyone cycling and we all die from inactivity-related diseases instead. They do not have our best interests at their core.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
All the above is CC-By-SA and no other implied copyright license to Cycle magazine.
Jdsk
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Re: Advice on Helmets prices vs quality ????

Post by Jdsk »

mjr wrote:
Jdsk wrote:As always I'd advise everyone to reread Goldacre and Spiegelhalter on the limits of our knowledge before and after turning to single studies.

Here are two much more recent analyses than that Cochrane Review:

"Bicycle injuries and helmet use: a systematic review and meta-analysis"
Olivier J and Creighton P
https://academic.oup.com/ije/article/46/1/278/2617198
Olivier J is a far more notorious campaigner than Clarke C who you refuse to read, so let's apply the same rule there?
That is incorrect. I've read everything written by Colin Clarke that has been mentioned here since I joined this forum.

I'm totally in favour of campaigning. I have no problem with researchers also being campaigners.

My concerns are about the distinction between reports that have been accepted for publication and those that haven't, and those that have been peer reviewed and those that haven't. But it also relates to self-citation without declaration of interest. And not answering questions following posts... such the one about that p value...

Jonathan
Last edited by Jdsk on 31 Mar 2021, 8:13pm, edited 1 time in total.
Jdsk
Posts: 24835
Joined: 5 Mar 2019, 5:42pm

Re: Advice on Helmets prices vs quality ????

Post by Jdsk »

Jdsk wrote:
Jdsk wrote:
Steady rider wrote:https://bmjopensem.bmj.com/content/bmjo ... 6.full.pdf
Taking another look at this recent paper, 28 cases, 20 had previous concussions. Bicycling-related concussions leading to postconcussion syndrome in adults’, details ‘The mean duration of PCS for helmet wearers was 22.9 months, and 16.8 months for patients not wearing a helmet at the time of concussion (p=0.41)’
You've now quoted that twice. What do you think that p value means, please?
Would you like me to answer for you?
Steady rider wrote:I am more interested in seeing how the 0.41 p value was calculated, it could be helpful if you can provide the calculation.
You quoted it, not me.

You posted that in an attempt to show that the duration was longer for helmet wearers. But that p value means that that cannot be concluded from the available data, it's a result that could have easily arisen by chance in this study with there being no real difference.
https://en.wikipedia.org/wiki/P-value

Now let's look at what the authors of the study themselves concluded on policy:

"Brain injury prevention measures suggested by this study include legislation requiring all-age helmet use, addition of bicycling infra- structure and safe bicycling practices such as speed reduction."

But, as always, it's worth rereading Goldacre and Spiegelhalter.

Jonathan
ymfb
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Re: Advice on Helmets prices vs quality ????

Post by ymfb »

Mike Sales wrote:
ymfb wrote:I’m happy to accept RoSPAs advice.



ROSPA is a front to divert criticism of motorist supremacy.

https://www.badscience.net/wp-content/uploads/Screenshot-2013-12-13-17.12.05.png


Clearly if you believe that it’s pointless continuing the dialogue, please don’t take that as sign that you have won an argument or even a point, you are not worth my time.

I shall watch the football instead.

I
Two wheels preferred.
Mike Sales
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Re: Advice on Helmets prices vs quality ????

Post by Mike Sales »

ymfb wrote:
Mike Sales wrote:
ymfb wrote:I’m happy to accept RoSPAs advice.



ROSPA is a front to divert criticism of motorist supremacy.

https://www.badscience.net/wp-content/uploads/Screenshot-2013-12-13-17.12.05.png


Clearly if you believe that it’s pointless continuing the dialogue, please don’t take that as sign that you have won an argument or even a point, you are not worth my time.

I shall watch the football instead.

I


Did you read the BMJ editorial by Spiegelhalter and Goldacre?

They write that any benefit from helmet wearing is "too modest to capture".
Perhaps making the standard to be reached in driving tests equal to the standard in the Institute of Advanced Motorists test would be more effective. Or would this fail too many condidates?
I wonder why RoSPA does not campaign for this reform.
Last edited by Mike Sales on 31 Mar 2021, 8:44pm, edited 1 time in total.
It's the same the whole world over
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
Steady rider
Posts: 2749
Joined: 4 Jan 2009, 4:31pm

Re: Advice on Helmets prices vs quality ????

Post by Steady rider »

I think Jonathan is missing the point, this is an open forum where people express views, it is not providing a published paper and declaring interests or not. Peoples true IDs are often not provided and if this is good or bad is open to debate. I do not have to answer questions but often I will. I know the 0.4 value is not considered significant but is does not mean it has no value. Conference papers are considered well before the actual events and sometimes have been subject to peer review on large parts of the papers. Even if peer reviewed, it does not necessarily mean they of sound. Conference papers can include many details probably exceeding 3000 words and many peer review processes and publications limit the word count, prohibiting explaining in the level of detail that is sometimes needed for the helmet topic.
Effects of bicycle helmet wearing on accident and injury rates - 6600 words -

https://www.researchgate.net/publicatio ... jury_rates

Weaknesses with a meta-analysis approach to assessing cycle helmets. Feb 2017 http://worldtransportjournal.com/wp-con ... eb-opt.pdf word count 12959

Evaluation of Australia's bicycle helmet laws, The Sports Science Summit, O2 venue London UK http://www.cycle-helmets.com/au-assessment-2015.pdf Presented 14 January 2015. - 45 pages 14k+ word count

The important point is if the work adds value and understanding.
You can also get people with vested interests, selling helmets for example and wish to discredit anyone not promoting helmets.
Last edited by Steady rider on 31 Mar 2021, 8:11pm, edited 1 time in total.
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