The helmet section?

This sub-forum all discussions about this "lively" subject. All topics that are substantially about helmets will be moved here, if not placed here correctly in the first place.
axel_knutt
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Re: The helmet section?

Postby axel_knutt » 1 Oct 2016, 11:17am

Dave W wrote:• Helmets dramatically reduce head injury metrics in tests with crash dummy head-
forms and paediatric skulls.
• A large number of studies show that helmet wearers, if involved in a collision,
suffer fewer head injuries than un-helmeted cyclists.

Do you have any evidence or reasoned argument to offer on the subject of helmets affecting the behaviour of road users? What would you do if someone were to prevent you from using a helmet?
“I'm not upset that you lied to me, I'm upset that from now on I can't believe you.”
― Friedrich Nietzsche

Steady rider
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Re: The helmet section?

Postby Steady rider » 1 Oct 2016, 11:26am

Bambach et al provided details from New South Wales of differences between helmet wearers and non-wearers for cycle accidents with motor vehicles involved, as shown in Table 19. e.g. 55% of those not wearing a helmet were in the age 0-19 yrs.

Evaluation of Australia's bicycle helmet laws, The Sports Science Summit, O2 venue London UK http://www.cycle-helmets.com/au-assessment-2015.pdf
see Table 19 page 21

Dave W
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Re: The helmet section?

Postby Dave W » 1 Oct 2016, 1:16pm

axel_knutt wrote:
Dave W wrote:• Helmets dramatically reduce head injury metrics in tests with crash dummy head-
forms and paediatric skulls.
• A large number of studies show that helmet wearers, if involved in a collision,
suffer fewer head injuries than un-helmeted cyclists.

Do you have any evidence or reasoned argument to offer on the subject of helmets affecting the behaviour of road users? What would you do if someone were to prevent you from using a helmet?

I didn't write it, it was quoted from the Jersey report I linked to earlier, read through it if you like.

Nobody on here seems to have picked up on that report for some reason I have the pdf file downloaded and to me it seems the total opposite of many and more to my own conclusions. I'm no scientist mind and don't claim to be I'm also not a mathematician. I just report on things I've read which anyone can pick up.

I'm just a cyclist interested in helmet protection, I don't give a toss about helmet law.

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Re: The helmet section?

Postby Vorpal » 1 Oct 2016, 2:12pm

Dave W wrote:Nobody on here seems to have picked up on that report for some reason I have the pdf file downloaded and to me it seems the total opposite of many and more to my own conclusions. I'm no scientist mind and don't claim to be I'm also not a mathematician. I just report on things I've read which anyone can pick up.

That report is discussed at length on another thread, linked above. I also referred to it in my discussion about why people come to such different conclusions.
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Dave W
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Re: The helmet section?

Postby Dave W » 1 Oct 2016, 2:19pm

https://www.headway.org.uk/media/3407/t ... y-2014.pdf


I see, you have to forgive me I don't read all the threads on here which is why I'm probably reproducing stuff that's been done already.

What I can't get my head around is why all the Scientists, Mathematicians or Statistcal experts come to totally opposite conclusions given the same data. How an organisation like Headway can be so wrong?

axel_knutt
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Re: The helmet section?

Postby axel_knutt » 1 Oct 2016, 3:19pm

Dave W wrote:the Jersey report I linked to earlier, read through it if you like.

That report acknowledges that a cohort study is required to settle the matter, and that they have not done this, instead opting for yet more case-control studies that are biased in favour of wearing a helmet if risk compensation affects road user behaviour. Their excuse for this is that there are no cohort studies, and that to conduct one is not practical because it would be unethical to force people not to wear helmets for a control group.

Firstly if the proposed intervention is compulsory helmet legislation vs optional helmets, then the control group is optional helmet, and not forced non-helmet. Secondly they beg the question in arguing that it is unethical to force anyone not to wear a helmet. The purpose of any such study is to find out whether helmets are beneficial, so until the study were completed we don't know whether helmets or no helmets is the unethical option.

However, they are wrong when they argue that there are no cohort studies. In the 1970s the NHTSA conducted just such an experiment, and the result was that fatalities were higher in the group wearing helmets. To my knowledge, it is the only cohort study that's been done, so why in the intervening four decades hasn't it been repeated sufficient times to establish whether the result is statistically robust?
“I'm not upset that you lied to me, I'm upset that from now on I can't believe you.”
― Friedrich Nietzsche

Steady rider
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Re: The helmet section?

Postby Steady rider » 1 Oct 2016, 4:47pm

The fatality claim of 65% odds reduction is based on two reports and 159 deaths, one report from Western Australia in 1993, Cooke et al, involving 64 fatalities (1984-1992 period) of which they included 30 in the meta-analysis, 24 cases and 6 controls. Most of the 64 fatalities (59%) occurred in children or young adults less than 20 years of age. A second report based on data from Ontario, Canada in 2012, Persaud et al, involved 129 fatalities, where 30 had taken alcohol or drugs. The Persaud et al study does not mention the 30 that had taken alcohol or drugs. A question was reported;
What was the helmet wearing status of these individuals? Have the authors overestimated the value of helmets by not accounting for this factor?
. Persaud et al failed to answer the question or provide the information requested.

Cyclist fatalities occur from a range of situations, for example motor vehicle hitting the cyclist from behind. In this situation the bicycle may be the first point of impact.
For Australia this was reported more for rural accidents than urban. One report detailed;
More than two-thirds of the deaths of cyclists aged 5–17 years were the result of the cyclist failing to give way to oncoming traffic and about half of these cases occurred at intersections. A typical behaviour for the younger (preteenage) cyclists was to enter the intersection from a footway without dismounting and without looking
.
These types of situations may result in side impact where the legs, body and head may all come into contact with a vehicle and be severe due to drivers often having little warning and time to slow down. Data from the Netherlands reported 50% to 65% of cyclists were hit from the side by the front of the vehicle .

The definition used by Olivier and Creighton was;
Cycling fatalities with multiple injuries including the head were categorized as a head injury
.
It appears that young cyclists may have a higher proportion of side impacts due to riding either into the road or at junctions and could be more likely to suffer multiple injuries including the head. The wearing rates for the younger cyclists could on average be a little lower than adults . These aspects would probably affect the overall fatality risk and proportion of injuries apart from helmet use.

The meta-analysis with two reports on fatalities and one not providing details regarding alcohol and drug use and the overall approach not taking account of the differences in behaviour and type of accident means it lacks potentially important information. It is not sufficiently detailed to support reliable conclusions. The definition of head injury to include ‘multiple injuries’ may have a adverse effect on the soundness of the assessment

Steady rider
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Re: The helmet section?

Postby Steady rider » 1 Oct 2016, 6:43pm

https://www.headway.org.uk/media/3407/t ... y-2014.pdf
TRL stated;

The very large reductions often sometimes cited by opponents of cycle helmet
legislation, which have been based on early analyses of observations of cycling rates in
Australia in the 1990s, have not been observed elsewhere.


It was reported;
H) Increased risk of injury per cyclist since helmet laws were introduced
Several analyses have compared numbers of injuries with the numbers of cyclists. They all suggest that injuries per cyclist have increased from what would have been expected without helmet laws.
In New Zealand, from 1989 to 2011, average time spent cycling (on roads and footpaths) fell by 79% for children aged 5-12 (from 28 to 6 minutes per person per week) and 81% for 13-17 year olds (52 to 10 mins/person/week).
Adult cycling declined from 8 to 5 minutes/person/week then trended back up to 8 minutes. Graphs of cycle use over time provide strong evidence that the requirement to wear a helmet discouraged cycling.
The reductions in cycling were accompanied by increased injury rates. Between 1989 and 2012, fatal or serious injuries per million hours of cycling increased by 86% for children (from 49 to 91), 181% for teenagers (from 18 to 51) and 64% for adults (from 23 to 38).

Clarke CF, Evaluation of New Zealand’s bicycle helmet law , Med J NZ ,
http://www.cycle-helmets.com/nz-clarke-2012.pdf

New Zealand survey data showed that average hours cycled per person
reduced by 51%.


http://www.cyclehelmets.org/1201.html Canada
There are in fact sharp falls in cycling after legislation evident in the data, which the authors do not draw attention to.

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Cunobelin
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Re: The helmet section?

Postby Cunobelin » 1 Oct 2016, 6:49pm

Dave W wrote:• Helmets dramatically reduce head injury metrics in tests with crash dummy head-
forms and paediatric skulls.
• A large number of studies show that helmet wearers, if involved in a collision,
suffer fewer head injuries than un-helmeted cyclists.



Why is that relevant?

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mjr
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Re: The helmet section?

Postby mjr » 2 Oct 2016, 6:21pm

The Jersey report was published so late to stop rebuttals being available before the vote. Based on that obvious flawed evidence, Jersey decided to force children to wear helmets, a measure that would have saved ZERO lives in the preceding years. It's almost as bad an example of how one zealot (Headway's chairman, I think?) can bypass democratic scrutiny as New Zealand's helmet rule.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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Stevek76
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Re: The helmet section?

Postby Stevek76 » 2 Oct 2016, 6:43pm

Dave W wrote:How an organisation like Headway can be so wrong?


Well headway are going to suffer from the same biases as medical staff, they see the unpleasant outcomes of brain injuries all the time, but it in no way means they are in a better position than the chap down the pub in how to prevent them.

Headway's irrationality is exposed in the fact that they have a long running campaign for cycle helmets but not for the many other daily activities that result in, often more, head and brain injuries.

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Cunobelin
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Re: The helmet section?

Postby Cunobelin » 3 Oct 2016, 6:28am

Stevek76 wrote:
Dave W wrote:How an organisation like Headway can be so wrong?


Well headway are going to suffer from the same biases as medical staff, they see the unpleasant outcomes of brain injuries all the time, but it in no way means they are in a better position than the chap down the pub in how to prevent them.

Headway's irrationality is exposed in the fact that they have a long running campaign for cycle helmets but not for the many other daily activities that result in, often more, head and brain injuries.



Exactly the point, Headway finds the majority of head injuries acceptable, and has no interests whatsoever in their prevention

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Cunobelin
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Re: The helmet section?

Postby Cunobelin » 3 Oct 2016, 6:29am

mjr wrote:The Jersey report was published so late to stop rebuttals being available before the vote. Based on that obvious flawed evidence, Jersey decided to force children to wear helmets, a measure that would have saved ZERO lives in the preceding years. It's almost as bad an example of how one zealot (Headway's chairman, I think?) can bypass democratic scrutiny as New Zealand's helmet rule.


Again raising the question why they have to lie and cheat if the evidence is actually that strong

Dave W
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Re: The helmet section?

Postby Dave W » 3 Oct 2016, 7:43am

Cunobelin wrote:
Stevek76 wrote:
Dave W wrote:How an organisation like Headway can be so wrong?


Well headway are going to suffer from the same biases as medical staff, they see the unpleasant outcomes of brain injuries all the time, but it in no way means they are in a better position than the chap down the pub in how to prevent them.

Headway's irrationality is exposed in the fact that they have a long running campaign for cycle helmets but not for the many other daily activities that result in, often more, head and brain injuries.



Exactly the point, Headway finds the majority of head injuries acceptable, and has no interests whatsoever in their prevention


Really? Bit strong I would think.

"Our mission is:
To promote understanding of all aspects of brain injury and provide information, support and services to survivors, their families and carers. In addition, Headway will campaign to reduce the incidence of brain injury."

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pjclinch
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Re: The helmet section?

Postby pjclinch » 3 Oct 2016, 8:16am

Dave W wrote:Really? Bit strong I would think.

"Our mission is:
To promote understanding of all aspects of brain injury and provide information, support and services to survivors, their families and carers. In addition, Headway will campaign to reduce the incidence of brain injury."


That might be their self-set mission, but there again the government's self-set mission is doing a good job of running the country and what they say they're trying to do and what they deliver aren't necessarily the same thing.

So the use of helmets in cars would make plenty of sense, but they don't say anything about that. They are, in other words, heavily swayed by bias that tends to influence much human endeavour, and as is true in many cases, once they've got an idea it's very hard for them to lose their grip on it. You get a lot of motivated, well meaning people working for what they see as the public good, and they lack the training and detachment to see they don't have the basis they think for that.

Similarly, TRL have an excellent record in policy-based evidence making. Their RSR30 paper is what the DfT will send you if you ask your MP why the Highway Code says you should wear a helmet, and it has a narrow range of references all from one end of the spectrum: publication bias. If you only refer to the evidence you like, you get the answer you want, and TRL have form there. Their PPR446 report (all 120 odd pages of it) deserves special mention, for admitting in the text they don't know how effective helmets are, but making an assumption plucked from the air that they are positively quite useful and using that as the basis for, errrr, proving they're positively quite useful (and no, I'm not making that up).

What's particularly interesting about the BMJ editorial by Spiegelhalter and Goldacre is they give you an answer that nobody really wants, including themselves. They admit their tools aren't up to the job of answering the questions, and in all likelihood will continue not to be. That's not the basis for a public health recommendation or requirement, though it says nothing about individual choice.

Another one I think is good is Tim Gill's Cycling and Children and Young People, where the author demonstrates there's no clear consensus and we're left with a "we do't really know" which isn't a basis for promotion or requirement. The author also has the courage to say he wears a helmet, had his daughter do the same, but it was down to "what if...?" gut feeling rather than the sort of evidence that can reasonably be used to guide public policy. In other words, an individual decision is made on a different basis to a general recommendation, recognising the effect of personal bias.

Pete.

(edited to add link to Gill's consultation report)
Often seen riding a bike around Dundee...