Study finds that wearing a cycle helmet may diminish ability to assess risk

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.
poetd
Posts: 92
Joined: 16 Jul 2019, 6:12pm

Re: Study finds that wearing a cycle helmet may diminish ability to assess risk

Postby poetd » 26 Aug 2019, 9:25pm

So lab based studies on the effectiveness of helmets are a complete waste because they don't take real world scenarios into account?

But wearing a helmet in a lab to play a card game is valid because..... ?


:roll:

User avatar
Wanlock Dod
Posts: 556
Joined: 28 Sep 2016, 5:48pm

Re: Study finds that wearing a cycle helmet may diminish ability to assess risk

Postby Wanlock Dod » 26 Aug 2019, 10:04pm

poetd wrote:But wearing a helmet in a lab to play a card game is valid because..... ?

It can provide valuable insights into some limited aspects of helmet use in an environment where other confounding factors can be minimised and controlled. Those insights can in turn assist in the interpretation of more complex empirical studies in real world conditions.

I have often wondered why given all of the demonstrable benefits of cycle helmets they don’t seem to be able to actually make cyclists safer in real world situations, can you offer any insights into why that might be?

User avatar
bovlomov
Posts: 4202
Joined: 5 Apr 2007, 7:45am
Contact:

Re: Study finds that wearing a cycle helmet may diminish ability to assess risk

Postby bovlomov » 26 Aug 2019, 10:23pm

poetd wrote:So lab based studies on the effectiveness of helmets are a complete waste because they don't take real world scenarios into account?

But wearing a helmet in a lab to play a card game is valid because..... ?

:roll:

No eye roll necessary.

The previous poster was making the point that this type of lab based study does not take real world scenarios into account (in ways he explains). Earlier comments about the card game made the point that the results were valid in that they revealed a particular aspect of human psychology.

poetd
Posts: 92
Joined: 16 Jul 2019, 6:12pm

Re: Study finds that wearing a cycle helmet may diminish ability to assess risk

Postby poetd » 27 Aug 2019, 2:29pm

Wanlock Dod wrote:I have often wondered why given all of the demonstrable benefits of cycle helmets they don’t seem to be able to actually make cyclists safer in real world situations, can you offer any insights into why that might be?


Because you are analysing the wrong data.

A helmet cannot prevent an accident occuring. There's no reason to think it would.
If you measure by that standard, then it's easy to prove that helmets have no effect.

However, the vast body of research out there shows that helmets DO help to reduce the severity of head injury.
If we measure by that standard - then enforced legislation starts to look downright common sense - which is of course why anti-helmet advocates refuse to acknowledge that data.

https://www.sciencedirect.com/science/a ... 7587900029
Analysis of the crude, unadjusted data showed a statistically significant association between helmet use and reduced severity of head injury

https://uk.reuters.com/article/us-healt ... KKCN10U1LY
Researchers found that people wearing helmets had 52 percent lower risk of severe TBI, compared to unhelmeted riders, and a 44 percent lower risk of death.
Riders with helmets also had 31 percent lower odds of facial fractures. The upper part of the face, particularly around the eyes, was most protected

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3800611/
These data demonstrate that lack of helmet use is significantly correlated with abnormal head CT scans (fractures), admission to the hospital, admission to the ICU, and overall worse TBI severity both in the prehospital and ED environments

https://academic.oup.com/heapro/article/22/3/191/598707
Most bicycle-related accidents with head injuries (70%) happen without the involvement of motor vehicles (single accidents), but this study shows a decrease in head injuries also in collisions with motor vehicles. It also shows a decrease in both concussion and skull fracture.

https://www.abc.net.au/science/articles ... 751304.htm
The team found cyclists without helmets were 5.6 times more likely to suffer any head injury than cyclists wearing a helmet and 5.5 times more likely to suffer a severe head injury.



So it's not like the benefits aren't measured and known, you're just chosing to ignore them in favour of other cherry-picked data which supports your position.

User avatar
Wanlock Dod
Posts: 556
Joined: 28 Sep 2016, 5:48pm

Re: Study finds that wearing a cycle helmet may diminish ability to assess risk

Postby Wanlock Dod » 27 Aug 2019, 2:55pm

So why is it that risks to cyclists are so great in countries where helmets are relatively popular with cyclists? If they really are as effective as is suggested surely cycling should be safe in places where they are used the most.

It almost seems as though the protection that they offer is inappropriate to the conditions that people are using them for.

poetd
Posts: 92
Joined: 16 Jul 2019, 6:12pm

Re: Study finds that wearing a cycle helmet may diminish ability to assess risk

Postby poetd » 27 Aug 2019, 3:01pm

Wanlock Dod wrote:So why is it that risks to cyclists are so great in countries where helmets are relatively popular with cyclists? If they really are as effective as is suggested surely cycling should be safe in places where they are used the most.



So, just so I'm getting your terrible circular logic correct here:

Countries with less safe cycling infrastructure leads to a situation where more riders chose to wear helmets. Yes?

By what mechanism are you suggesting (by route of your tortured logic) that helmets improve infrastructure?

Pete Owens
Posts: 1681
Joined: 7 Jul 2008, 12:52am

Re: Study finds that wearing a cycle helmet may diminish ability to assess risk

Postby Pete Owens » 27 Aug 2019, 3:17pm

poetd wrote:Would I ride without one now? Would depend on the journey and location. In city centre rush hour traffic? Probably not no to be honest.

Quite. That is an extreme version of risk compensation - ie when you wear a helmet or other protective kit you take risks that you wouldn't otherwise take. It is true for any safety intervention where the protection is perceived by the person in control of the risk.

It is usually sub-conscious and more subtle than that - a seat-belted driver will drive about 3mph faster. Anti-lock brakes mean bends are approached with that bit less caution and so on.

poetd
Posts: 92
Joined: 16 Jul 2019, 6:12pm

Re: Study finds that wearing a cycle helmet may diminish ability to assess risk

Postby poetd » 27 Aug 2019, 3:20pm

Pete Owens wrote:Quite. That is an extreme version of risk compensation - ie when you wear a helmet or other protective kit you take risks that you wouldn't otherwise take. It is true for any safety intervention where the protection is perceived by the person in control of the risk.


But that is a different argument to the one that is trying to be made in this thread - it is not the helmet that is affecting my perception of the risk but the set and setting of a busy city centre where pedestrians are happy to walk straight out in front of you due to increased mobile phone usage.
The helmet in that instance is a reaction not a cause.

User avatar
mjr
Posts: 15030
Joined: 20 Jun 2011, 7:06pm
Location: Norfolk or Somerset, mostly
Contact:

Re: Study finds that wearing a cycle helmet may diminish ability to assess risk

Postby mjr » 27 Aug 2019, 3:34pm

poetd wrote:
Wanlock Dod wrote:I have often wondered why given all of the demonstrable benefits of cycle helmets they don’t seem to be able to actually make cyclists safer in real world situations, can you offer any insights into why that might be?


Because you are analysing the wrong data.

I'm reminded of the expression "garbage in, garbage out" so often when looking at studies that supposedly prove cycle helmets protect. Of course if someone fixes the data first, they can prove anything: figures can't lie but liars can figure, like the proverb says.

poetd wrote:A helmet cannot prevent an accident occuring. There's no reason to think it would.
If you measure by that standard, then it's easy to prove that helmets have no effect.

But the converse is true: clearly a helmet can cause a crash (not accident, please - most of the data includes the reasonably forseeable crashes too). In the extreme case, a loose helmet falling forwards and covering the eyes can cause the rider to crash. Surely you can at least agree that?

However, the vast body of research out there shows that helmets DO help to reduce the severity of head injury.
If we measure by that standard - then enforced legislation starts to look downright common sense - which is of course why anti-helmet advocates refuse to acknowledge that data.

That's a misleading standard. The vast body of helmet-favouring research mostly repeatedly shows that helmets probably help a little IF someone crashes, which is something few dispute. What they do not show is whether helmets help without the conditional - in other words, that helmet use improves outcomes - and that's what we care about, the outcomes of the whole population, not only mitigating the subset that crash.

If we can reduce the size of the subset that crash - reduce the number of crashes, bluntly - then that will dwarf the effect of cycle helmets... and if cycle helmet use causes more crashing, as many studies suggest, then it makes more sense to ban them, like banning F1 motor racing helmets and collars from driving on the grounds of restricting hearing and vision.

https://www.sciencedirect.com/science/article/abs/pii/0001457587900029
Analysis of the crude, unadjusted data showed a statistically significant association between helmet use and reduced severity of head injury

The injury data in that one does not seem to contain helmet use. While falling head injury rates may correlate with growing helmet use in that case (and helmet use data is in another paper I have not even glanced at), both correlate with time (of course) and no causal link is shown. It seems strange that the researchers grasp at the helmet straw as the sole "probably" to cause the head injury rate reduction.

https://uk.reuters.com/article/us-health-bicycles-helmets/helmets-prevent-severe-head-injuries-in-bike-accidents-idUKKCN10U1LY
Researchers found that people wearing helmets had 52 percent lower risk of severe TBI, compared to unhelmeted riders, and a 44 percent lower risk of death.
Riders with helmets also had 31 percent lower odds of facial fractures. The upper part of the face, particularly around the eyes, was most protected

No citation, unverifiable. Sorry for not hunting it down.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3800611/
These data demonstrate that lack of helmet use is significantly correlated with abnormal head CT scans (fractures), admission to the hospital, admission to the ICU, and overall worse TBI severity both in the prehospital and ED environments

Mixes up 143 bicycle riders among their 478 injured people. The cyclists are 73% male and median age 26, which is even more skewed to young males than the cycling population. 50 of the 143 injured cyclists were off-roading. It seems a stronger argument for being older, female and staying on-road than for using a helmet.

As ever, studying only injured people is flawed because it tells you nothing of whether helmet use makes an injurious crash more likely.

https://academic.oup.com/heapro/article/22/3/191/598707
Most bicycle-related accidents with head injuries (70%) happen without the involvement of motor vehicles (single accidents), but this study shows a decrease in head injuries also in collisions with motor vehicles. It also shows a decrease in both concussion and skull fracture.

Showing a protective effect beyond the design limits of the helmet clearly calls the study methodology into question. It is not quite as conspicuous as the study with the data that suggested that helmet use protects your arms and legs, but it still seems pretty incredible and suggests something other factor at work.

https://www.abc.net.au/science/articles/2013/05/06/3751304.htm
The team found cyclists without helmets were 5.6 times more likely to suffer any head injury than cyclists wearing a helmet and 5.5 times more likely to suffer a severe head injury.

No citation, unverifiable, but I strongly suspect this was another study that actually found cyclists that crashed without helmets were 5.6 times more likely [...] than cyclists that crashed wearing a helmet (and so on). The "that crashed" so often gets lost in reporting of these studies and it is a very very big conditional which changes the nature of the study population entirely.

So it's not like the benefits aren't measured and known, you're just chosing to ignore them in favour of other cherry-picked data which supports your position.

That seems very similar to ignoring the flaws in the above studies and misrepresenting them by omitting words like "that crashed" and "probably" from the results - why did you choose to do that?
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.

Mike Sales
Posts: 4460
Joined: 7 Mar 2009, 3:31pm

Re: Study finds that wearing a cycle helmet may diminish ability to assess risk

Postby Mike Sales » 27 Aug 2019, 3:48pm

poetd wrote:
Wanlock Dod wrote:So why is it that risks to cyclists are so great in countries where helmets are relatively popular with cyclists? If they really are as effective as is suggested surely cycling should be safe in places where they are used the most.



So, just so I'm getting your terrible circular logic correct here:

Countries with less safe cycling infrastructure leads to a situation where more riders chose to wear helmets. Yes?

By what mechanism are you suggesting (by route of your tortured logic) that helmets improve infrastructure?


If helmets make cycling safer, then countries where they are worn by law, like New Zealand and Australia, should have a much better injury rates for cyclists than countries where only a fraction of cyclists wear polystyrene, like the UK.
These countries have a much worse injury rate than the UK. This is not because of our extensive network of safe cycling facilities.
When a country like New Zealand makes all its cyclists wear a helmet, then, if helmets are all they are cracked up to be, then cycling injuries should tumble.
Take a look at this graph.

https://roaddangerreductionforum.files.wordpress.com/2013/12/newzealandhelmetsv6.jpg

The statistics from which it is prepared are from the NZ Government.

This is what it shows.

Injuries went from about 500 per 100,000 cyclists before the law was enforced, to about 900 per 100,00 cyclists after the law.
The number of cyclists went from about 250,000 to about 150,000.

Cycle facilities were not abolished.

fastpedaller
Posts: 2335
Joined: 10 Jul 2014, 1:12pm
Location: Norfolk

Re: Study finds that wearing a cycle helmet may diminish ability to assess risk

Postby fastpedaller » 27 Aug 2019, 3:59pm

poetd wrote:A helmet cannot prevent an accident occuring.


But a helmet can lead to more likelyhood of an accident occurring if a motorised driver thinks

"Nah - I'll take that gap, he's wearing a helmet, he'll not get hurt"

There are people who think that - generally the advocates of helmet wearing.
Similarly I've heard car driver say "I'm ok on ice, my car's got ABS" and they believe it!

poetd
Posts: 92
Joined: 16 Jul 2019, 6:12pm

Re: Study finds that wearing a cycle helmet may diminish ability to assess risk

Postby poetd » 27 Aug 2019, 4:02pm

Mike Sales wrote:
If helmets make cycling safer, then countries where they are worn by law, like New Zealand and Australia, should have a much better injury rates for cyclists than countries where only a fraction of cyclists wear polystyrene, like the UK.
These countries have a much worse injury rate than the UK. This is not because of our extensive network of safe cycling facilities.
When a country like New Zealand makes all its cyclists wear a helmet, then, if helmets are all they are cracked up to be, then cycling injuries should tumble.



Again another example of refusing to look at the data which doesn't serve your purpose.

Injury "rates" are not the same as injury "severity".

Your attempts to confuse the two are naive at best, or deliberately disingenuous at worst.




Mike Sales wrote:
Take a look at this graph.

https://roaddangerreductionforum.files.wordpress.com/2013/12/newzealandhelmetsv6.jpg

The statistics from which it is prepared are from the NZ Government.

Injuries went from about 500 per 100,000 cyclists before the law was enforced, to about 900 per 100,00 cyclist after the law.
The number of cyclist went from about 250,000 to about 150,000.

Cycle facilities were not abolished.


Those figures tell us nothing about the types of cyclists nor where they were cycling.

The reduced number of cyclists could be telling us that those that did remain as cyclists did so due to events or racing activities (where they would already have been wearing a helmet and so wouldn't have been affected by introduction of legistlation) - where higher rates of accidents are a natural given due to higher speeds and the nature of racing - so the (temporary) reduction in cyclists - leaving a higher proportion of those involved in more risky events would happily answer that without any shady semantics to hide the real cause of those figures.

Mike Sales
Posts: 4460
Joined: 7 Mar 2009, 3:31pm

Re: Study finds that wearing a cycle helmet may diminish ability to assess risk

Postby Mike Sales » 27 Aug 2019, 4:10pm

poetd wrote:

Again another example of refusing to look at the data which doesn't serve your purpose.

Injury "rates" are not the same as injury "severity".

Your attempts to confuse the two are naive at best, or deliberately disingenuous at worst.






The reduced number of cyclists could be telling us that those that did remain as cyclists did so due to events or racing activities (where they would already have been wearing a helmet and so wouldn't have been affected by introduction of legistlation) - where higher rates of accidents are a natural given due to higher speeds and the nature of racing - so the (temporary) reduction in cyclists - leaving a higher proportion of those involved in more risky events would happily answer that without any shady semantics to hide the real cause of those figures.


You neglect to give us the slightest evidence that the extra injuries are less severe (does that make them acceptable?)
yet your unevidenced explanation allows you to call me disingenuous! Have you the slightest reason to assert that I am naïve, beyond you conviction that helmets are effective?

You move easily from saying that your guesses "could" explain away the evidence to assuming that they must be right. On this basis you accuse me of lying, for this is what disingenuous means. I am annoyed to be accused of "shady semantics" too, without you bothering with real evidence.

Have you had a look at Goldacre and Spiegelhalter yet?

Spiegelhalter's job is informing the public about risk. He has found no good evidence that helmets work.
Last edited by Mike Sales on 27 Aug 2019, 5:10pm, edited 1 time in total.

poetd
Posts: 92
Joined: 16 Jul 2019, 6:12pm

Re: Study finds that wearing a cycle helmet may diminish ability to assess risk

Postby poetd » 27 Aug 2019, 4:15pm

Mike Sales wrote:
You neglect to give us the slightest evidence that the extra injuries are less severe



Scroll up a few posts, a small selection of the large amount of medical evidence available.

Mike Sales
Posts: 4460
Joined: 7 Mar 2009, 3:31pm

Re: Study finds that wearing a cycle helmet may diminish ability to assess risk

Postby Mike Sales » 27 Aug 2019, 4:18pm

poetd wrote:
Mike Sales wrote:
You neglect to give us the slightest evidence that the extra injuries are less severe



Scroll up a few posts, a small selection of the large amount of medical evidence available.


What I was asking for was evidence to show that the big jump in injuries to NZ cyclists is due to an increase in trivial injuries, or even that the smaller number of more severe injuries was overwhelmed by a larger number of less severe injuries.
After all, you accused me of being disingenuous in presenting the evidence that the NZ helmet law failed badly. Your deeply held belief that helmets are good and that therefor there must be confounding factors, is not an adequate basis to accuse me of lying.

Go on, give us a few tasters.
And whilst you are at it, send an e-mail to Goldacre putting him right. He must have missed all your evidence. Yet he considers that the evidence for cycle helmets efficacy is a useful case for teaching epidemiology.
Last edited by Mike Sales on 27 Aug 2019, 4:41pm, edited 1 time in total.