Evaluating the impact of cycle helmet use...

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: Evaluating the impact of cycle helmet use...

Postby Jdsk » 10 Jul 2020, 9:21am

If anyone wants a convenient introduction to Robinson's views I recommend

"Do enforced bicycle helmet laws improve public health?"`
BMJ 2006;332:722–5
https://www.bmj.com/content/bmj/332/7543/722.1.full.pdf

It's conveniently followed by a response with a different conclusion.

NB: She is discussing mandation. What pjclinch asserted above was the effect of helmet use. Quite different.

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Re: Evaluating the impact of cycle helmet use...

Postby pjclinch » 10 Jul 2020, 9:26am

Jdsk wrote:
pjclinch wrote:The conclusions are that at policy level the case for recommending or requiring helmets has not been properly made, but the author pointed out in a postscript he wore one and required his daughter to wear one for reasons he admitted didn't really cut it for a consultancy report.

There's nothing wrong with the precautionary principle when the level of evidence is inadequate for anything better. Of course the topical illustration of that is wearing a mask to prevent spread of a virus.


The benefit of the doubt is, I'm afraid, the Wrong Answer, because the doubt can go either way.

Say you're crossing a road, starting in a substantial bus shelter set back a little from the road edge. You have good sight lines and you can see traffic as it approaches. There's a car coming and you think it's touch and go whether you'd get over safely. In this case the benefit of the doubt means you stay where you are and wait for a bigger gap.
Now we change the rules, we're standing on a narrow verge and there is a risk to staying where we are, and the longer we stay there the greater the risk will be. Or we can take the risk trying to beat the traffic by zooming across the road. Which is safer? We can guess, but we don't actually know, so in that case "benefit of the doubt" doesn't work. The precaution of not trying to beat the traffic just opens up a different set of risks.
And so it is with helmets. We can't say for sure whether an individual is safer at the start of A Notional Journey with or without helmet. The particular context of that individual can inform their choice, but if we don't know it we're not in a safe position to advise them.

As Ian Walker pointed out in a tweet about Jake Olivier's helmet studies, the problem is confusing the question of "am I better off if I whack my head when I'm wearing this" with "am I safer on my bike trip if I wear this", and they're really not the same.

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pjclinch
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Re: Evaluating the impact of cycle helmet use...

Postby pjclinch » 10 Jul 2020, 10:08am

Jdsk wrote:
NB: She is discussing mandation. What pjclinch asserted above was the effect of helmet use. Quite different.


So you don't think an effect of mandating helmets would be to increase their use?
As it happens, it did increase their use, very quickly and substantially, which gives you a nice time point to compare Before and After. With so many more people wearing allegedly beneficial devices with a short period of change you'd think that serious injury rates would drop... but they didn't (headline numbers did, but at about the same rate that people stopped cycling).

There are studies in places without a law where you're looking at voluntary uptake, e.g. Hewson's work which used the historical ties between pedestrian and cycle fatalities over time in the UK as a baseline to get past the fact you don't have a convenient before/after point, the idea being that as cyclists start to use an intervention that pedestrians don't then they should perform comparably better, but... they don't.

And so on.

Raising an individual citation or four and saying it proves much in this field just doesn't cut the mustard.
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Re: Evaluating the impact of cycle helmet use...

Postby reohn2 » 10 Jul 2020, 10:22am

tim-b wrote:Hi
reohn2 wrote:
Marcus Aurelius wrote:......... Helmets save lives, end of, get over it.

I think you bought the blurb and are convinced that you'll die if you don't wear a helmet,when in fact nothing could be further from the truth.

"Results Non-use of a helmet was directly associated with death..." Read the "Discussion" section (link) for this Spanish study (after the "Abstract" section)
Regards
tim-b

What I took from reading it was that non helmeted cyclists were more likely to die in a crash,but it doesn't say from what injuries,the study also doesn't have any idea of speed at point of impact,there are many other variables such as time of day,alcohol consumption,road and weather conditions,age,etc,etc.
What seems to be conclusive is motors v cyclists is always the worst outcome for cyclists and IMO the faster the motor on impact the seriousness injury or death of the cyclist is more likely,helmeted or not.
I don't were a helmet but I also try not to use the faster major roads,try to remain as conspicuous as possible and never ride in the gutter.
Nor do I believe a helmet will save my life in the event of a collision with a motor with a high speed differential.
"Helmets save lives" is only a valid statement in certain circumstances and those circumstances are too many and varied to be conclusive.
When we accept the claim "helmets save lives" as a conclusive fact,which it isnt,we're on the road to complusion,which a situation I never want to see in the UK because I believe it'd be a retrograde step for cycling as a whole.
What I would like to see is for motorists to take responsibility for their unlawful actions in the form of better and more effective policing and far harsher penalties for those unlawful actions,because from what I see daily on UK roads is motorists being a law unto themselves as a result of that lack of policing,penalties and responsibility.
I would also like to see an abject fear by motorists of a collision with vulnerable road users in the form of a presumed liability law that puts blame on the larger vehicle unless proven otherwise.
Attemting to protect a vulnerable road user with a polystyrene hat of very limited proven use goes nowhere in this direction and for me and all other cyclists to wear them merely confirms the fact that motorists have cart blanch to treat me as an unworthy road user.

All that said,since this virus descended upon the country and many more people have taken up cycling I've seen an increase in driver awareness and more respect for me as a cyclist,though it's still far from ideal and remains to be seen whether the effect is long lasting or whether it's a short lived community feeling the virus has brought to the fore in an otherwise them and us road use situation I previously felt,though I'm not lowering my guard as IME motorists are as predictable as UK weather :wink:
Last edited by reohn2 on 10 Jul 2020, 10:42am, edited 1 time in total.
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Re: Evaluating the impact of cycle helmet use...

Postby Vorpal » 10 Jul 2020, 10:41am

pjclinch wrote:
Jdsk wrote:
pjclinch wrote:Or you could read the Goldacre/Spiegelhalter editorial which points out some of the confounding problems in doing the research, and why the research is such a mess that it doesn't really contribute much. I can cherry pick my way through the pile and "prove" all sorts of things, but if you look at the pile as a whole it tells you that there's a lot of noise and it obscures any signal. Taking a single study and saying "but this one says!" isn't really helpful.

Yes. Any sensible discussion from here on should be based on systematic review methods, not cherrypicked single studies.


Then you won't have a sensible discussion. The only thing claiming to be a systematic review is Jake Olivier's, but as he cherry picks the hospital studies which tend to come out strongly in favour for the confounding reasons pointed out, it's a bit of a nonsense.

Actually, Elvik looked at some systematic reviews (IIRC one of the authors was an Anderson, but I don't remember more).

Elvik found no overall benefit in the use of helmets. When he looked at Anderson's(?) review, he found some benefit in older studies that gradually decreased over time, and theorised that helmets used to provide some small benefit that has decreased with newer design and emphasis on cooling and weight.

I'm sure these have been discussed on here before, but I haven't the time at the moment to go looking.
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Re: Evaluating the impact of cycle helmet use...

Postby Jdsk » 10 Jul 2020, 10:47am

This paper?

"Publication bias and time-trend bias in meta-analysis of bicycle helmet efficacy: A re-analysis of Attewell, Glase and McFadden, 2001"
doi:10.1016/j.aap.2011.01.007
http://www.cycle-helmets.com/elvik.pdf

(It's not really a systematic review but it's in the same general area.)

Jonathan

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Re: Evaluating the impact of cycle helmet use...

Postby Vorpal » 10 Jul 2020, 10:51am

Jdsk wrote:This paper?

"Publication bias and time-trend bias in meta-analysis of bicycle helmet efficacy: A re-analysis of Attewell, Glase and McFadden, 2001"
doi:10.1016/j.aap.2011.01.007
http://www.cycle-helmets.com/elvik.pdf

(It's not really a systematic review but it's in the same general area.)

Jonathan

That looks like one of the articles about it, yes. I misremembered a couple of things; sorry about that. If you are interested, I think the whole study was published the Norwegian Transport Økonomisk Institute.
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Re: Evaluating the impact of cycle helmet use...

Postby Jdsk » 10 Jul 2020, 10:53am

I think that is the whole paper...

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Re: Evaluating the impact of cycle helmet use...

Postby Vorpal » 10 Jul 2020, 12:38pm

Jdsk wrote:I think that is the whole paper...

Jonathan

When I glanced at it, I thought something was missing. It's not that there is more to it, but that he updated it in 2013

https://reader.elsevier.com/reader/sd/p ... C23DBAD1F5
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Re: Evaluating the impact of cycle helmet use...

Postby Jdsk » 10 Jul 2020, 12:53pm

Thanks

Jonathan

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Re: Evaluating the impact of cycle helmet use...

Postby tim-b » 10 Jul 2020, 12:58pm

Hi
What I took from reading it was that non helmeted cyclists were more likely to die in a crash,but it doesn't say from what injuries,the study also doesn't have any idea of speed at point of impact,there are many other variables such as time of day,alcohol consumption,road and weather conditions,age,etc,etc.
What seems to be conclusive is motors v cyclists is always the worst outcome for cyclists and IMO the faster the motor on impact the seriousness injury or death of the cyclist is more likely,helmeted or not.
I don't were a helmet but I also try not to use the faster major roads,try to remain as conspicuous as possible and never ride in the gutter.
Nor do I believe a helmet will save my life in the event of a collision with a motor with a high speed differential.
"Helmets save lives" is only a valid statement in certain circumstances and those circumstances are too many and varied to be conclusive.
When we accept the claim "helmets save lives" as a conclusive fact,which it isnt,we're on the road to complusion,which a situation I never want to see in the UK because I believe it'd be a retrograde step for cycling as a whole.
What I would like to see is for motorists to take responsibility for their unlawful actions in the form of better and more effective policing and far harsher penalties for those unlawful actions,because from what I see daily on UK roads is motorists being a law unto themselves as a result of that lack of policing,penalties and responsibility.
I would also like to see an abject fear by motorists of a collision with vulnerable road users in the form of a presumed liability law that puts blame on the larger vehicle unless proven otherwise.
Attemting to protect a vulnerable road user with a polystyrene hat of very limited proven use goes nowhere in this direction and for me and all other cyclists to wear them merely confirms the fact that motorists have cart blanch to treat me as an unworthy road user.

All that said,since this virus descended upon the country and many more people have taken up cycling I've seen an increase in driver awareness and more respect for me as a cyclist,though it's still far from ideal and remains to be seen whether the effect is long lasting or whether it's a short lived community feeling the virus has brought to the fore in an otherwise them and us road use situation I previously felt,though I'm not lowering my guard as IME motorists are as predictable as UK weather :wink:

Perversely I agree with most of what you said :) I'm in favour of freedom of choice, one difference between you and I is that I choose to wear a helmet.
""Helmets save lives" is only a valid statement in certain circumstances and those circumstances are too many and varied to be conclusive."
I wear a helmet in the event of those certain circumstances, but there are deniers who would disagree that helmets can save even one life and want to see everyone cycling bare-headed. The Spanish evidence is peer-reviewed, published by the BMJ and refutes the deniers' PoV. Admittedly it's a single-study, but the authors are quite open that "to (their) knowledge, there have been no attempts to analyse personal and environmental characteristics and their relationship with the risk of death."
Regards
tim-b
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Re: Evaluating the impact of cycle helmet use...

Postby Mike Sales » 10 Jul 2020, 1:15pm

The jurisdictions where helmets have been mandated are those, unsurprisingly, where cycling is relatively more dangerous.
Australia, NZ, South Africa and various states of the USA, are places where helmet laws are a substitute for more effective action. The laws have not made cycling noticeably safer.
As Chris Boardman has pointed out, helmets are a long way down the list of remedies.
All this fuss, all the interminable discussions, are irrelevant to making cycling safer and more appealing to those who do not enjoy dressing up in full roadie costume to get to school, the shops or work.
I think that helmet laws, and helmet promotion, could be called macro risk homeostasis. Any possible benefit is used up by the refusal to use proven ways of making cycling safer. They are an excuse and a diversion.
If you ride bare headed like me, you will be used to hearing, from the driver you manage to reprove for risking your life, "you should be wearing a helmet" (when you catch them up at the next lights).
I have even heard more explicit admissions. "If cyclists would wear helmets we wouldn't have to be so careful around them".

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Re: Evaluating the impact of cycle helmet use...

Postby pjclinch » 10 Jul 2020, 1:42pm

tim-b wrote:Perversely I agree with most of what you said :) I'm in favour of freedom of choice, one difference between you and I is that I choose to wear a helmet.


That's not at all perverse. There's no shortage of folk I know who are pretty much on the same page as me but are happier in a lid so they wear one.

tim-b wrote:""Helmets save lives" is only a valid statement in certain circumstances and those circumstances are too many and varied to be conclusive."


Again, you need to draw the distinction between population and individuals. So if we have something that saves 2 life but costs 3 then that's Bad News at the policy/population level but is absolutely sweet for the two it saved. And even though it has killed more than it's saved you can still legitimately say it's saved lives. But that's not a great reason to recommend it to everyone!

tim-b wrote:I wear a helmet in the event of those certain circumstances, but there are deniers who would disagree that helmets can save even one life and want to see everyone cycling bare-headed.


The "deniers", the much vaunted "anti helmet brigade", are by and large the figments of imaginations. There are people who are genuinely anti helmet (The Utility Cyclist on these boards has stated he is, for example), but for the most part people like me are looking at net results for helmet uptake and are entirely happy for folk that want to wear helmets to do that. Yes, I can see a circumstance where an EN1078 hat will save a life but that's not the same thing as being able to assume more lives will be saved than lost through all sorts of mechanisms.

tim-b wrote:The Spanish evidence is peer-reviewed, published by the BMJ and refutes the deniers' PoV. Admittedly it's a single-study, but the authors are quite open that "to (their) knowledge, there have been no attempts to analyse personal and environmental characteristics and their relationship with the risk of death."


There are hundreds of peer reviewed papers in dozens of reputable journals saying all sorts of things. That they got published means someone thought they might have something worth discussing, and if it's the first paper on it it's a welcome start to a line of enquiry, but almost certainly not the last word. If someone like Goldacre, who is an evidence geek and loves complexity and sorting it out, says that it's really difficult then it's almost certainly really difficult.

The "deniers" are denying there is clear evidence a random rider must be safer (where "safer" is at the level of a life-changing injury) in a helmet than not. That's not the same thing as nobody should wear one.
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Re: Evaluating the impact of cycle helmet use...

Postby tim-b » 10 Jul 2020, 2:17pm

Hi
As Chris Boardman has pointed out, helmets are a long way down the list of remedies

I couldn't agree more; in the hierarchy of hazard control measures PPE is the last resort. It isn't your or my refusal to use proven ways of making cycling safer that's the stumbling block, but I don't suppose that'll change in my lifetime and so I'll continue to wear a helmet
All this fuss, all the interminable discussions, are irrelevant to making cycling safer and more appealing to those who do not enjoy dressing up in full roadie costume to get to school, the shops or work.
I think that helmet laws, and helmet promotion, could be called macro risk homeostasis. Any possible benefit is used up by the refusal to use proven ways of making cycling safer. They are an excuse and a diversion.

That's your interpretation which is fine, but I want others to have freedom of choice, and dressing threads up with a disingenuous title as happened on this sub-forum earlier this week doesn't make cycling safer and definitely doesn't make cycling more appealing
Regards
tim-b
Last edited by tim-b on 10 Jul 2020, 2:22pm, edited 2 times in total.
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Re: Evaluating the impact of cycle helmet use...

Postby tim-b » 10 Jul 2020, 2:18pm

@pjclinch
Thank you. Some genuinely interesting thoughts
Regards
tim-b
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