Do the helmets in accidents involving helmets get investigated?

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mjr
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Re: Do the helmets in accidents involving helmets get investigated?

Postby mjr » 17 Apr 2018, 11:42am

pjclinch wrote:
mjr wrote:If all users actually strapped the helmet on tightly enough for it not to move around, you might have a point, but many of them really do seem to have difficulty keeping the helmet steady on top of their head...


I've never seen anyone have difficulty keeping a lid on their head, and that's in the context of a Bikeability instructor where there's been years of hilariously mis-fitted examples.

I've highlighted the missing word which means the reply didn't actually refute the claim. The helmet doesn't need to fall - it just needs to slip around enough to annoy. Users of loose ones really do seem to try to keep their head more vertically-aligned than non-users... this probably has some effect.

pjclinch wrote:I'm no fan of helmets but demonising them with obvious non-sequiturs really doesn't help anybody.

On the one hand, demonising non-wearers is widespread and I don't think logic is working, so let's make fun of strapping a chamber pot to one's head! On the other hand, I think you're blowing a parenthetical "I'm always reminded of" out of all proportion by misinterpreting it a strict analogy instead of a visual similarity.
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Re: Do the helmets in accidents involving helmets get investigated?

Postby mjr » 17 Apr 2018, 11:43am

Vorpal wrote:
mjr wrote: Do you think balancing a quarter-pound weight on top of one's head could maybe perhaps affect one's balance?

Damn. I guess I'd better get a haircut. :wink:

If it's all on top of your head, haven't you already had one, or at least extensive pinning? ;)

Would that I still had that much hair...
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Re: Do the helmets in accidents involving helmets get investigated?

Postby horizon » 17 Apr 2018, 11:55am

pjclinch wrote:
You might take it as a "no", but that's not the same thing as "no reliable evidence that helmets protect at all".

To protect at all is a very low hurdle. To prove an EN1078 helmet can protect at all have someone drop a cricket ball on your head from a couple of meters up with and without a helmet. If the helmet example is less uncomfortable it has protected you to some degree. It hasn't saved your life, but it's quite possibly saved you a bit of a headache, and that is some measure of useful protection.

This is not, of course, anything to do with protection from serious or fatal injury in any number of modes of cycle crashes, but that is (a) not what you asked and (b) not what they're designed for, which is more mitigation of minor injury. There is no reliable evidence that if two notionally identical "average" cyclists start the same notionally "normal" journey, one with and one without a helmet, that either one will clearly be in less chance of ending up in A&E than the other. But that's not the same thing as no reliable evidence a helmet can be of any use.

Pete.


I was hoping for some investigative evidence relating to a helmet actually used in an accident and/or conversely an accident not involving a helmet. My presumption is that minor accidents don't get investigated at all but I'm wonderting if it is these accidents where the best evidence might lie: yes, you had a fall, no you weren't injured: but why not?

Even if it is purported to be shown in some other way that helmets prevent minor injury but especially if no such evidence is currently available for serious injury, I personally would conclude that helmets are effectively useless.

(BTW I'm quite astonished that no such investigations take place and I feel confident that this forum would know of such studies had they occurred).
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Re: Do the helmets in accidents involving helmets get investigated?

Postby Mike Sales » 17 Apr 2018, 12:15pm

horizon wrote:
(BTW I'm quite astonished that no such investigations take place and I feel confident that this forum would know of such studies had they occurred).


I suppose you have looked at http://www.cyclehelmets.org/ ?

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Re: Do the helmets in accidents involving helmets get investigated?

Postby horizon » 17 Apr 2018, 12:31pm

Mike Sales wrote:
horizon wrote:
(BTW I'm quite astonished that no such investigations take place and I feel confident that this forum would know of such studies had they occurred).


I suppose you have looked at http://www.cyclehelmets.org/ ?


I've had another brief look but cannot find any links to investigations of actual accidents.
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Re: Do the helmets in accidents involving helmets get investigated?

Postby Vorpal » 17 Apr 2018, 12:58pm

It seems to me that there was a study at a Swedish university. IIRC, Elvik has referenced it in a couple of his papers. I will see if I can find it when I get a chance.
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Re: Do the helmets in accidents involving helmets get investigated?

Postby mjr » 17 Apr 2018, 1:02pm

horizon wrote:
Mike Sales wrote:
horizon wrote:
(BTW I'm quite astonished that no such investigations take place and I feel confident that this forum would know of such studies had they occurred).


I suppose you have looked at http://www.cyclehelmets.org/ ?


I've had another brief look but cannot find any links to investigations of actual accidents.

I remember one recent research report looking at actual fatal accidents, but they did not examine the helmets. Instead, they examined the proportions of dead users and non-users, plus the fatal injuries of dead non-users to estimate how many they felt could have been "saved" if they used helmets. I do not seem to have saved a copy of the report, probably because it seemed flawed to me to ignore the possibility that crash rate was not independent of usage.
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Re: Do the helmets in accidents involving helmets get investigated?

Postby horizon » 17 Apr 2018, 1:15pm

Vorpal, mjr: many thanks for that. The kind of information i thought might be available is of the forensic kind - speed of impact, what injury and why, effect on helmet etc. None of this is rocket science and I would have thought, given the high profile given to helmets, someone might have done it either to prove the case overall or to demonstrate the superiority of their own brand.

For me this is a bit of an epiphany: if the evidence doesn't exist then I think the case on helmets is effectively closed.
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Re: Do the helmets in accidents involving helmets get investigated?

Postby Wanlock Dod » 17 Apr 2018, 1:36pm

I think that the source of the problem is basically the discrepancy between the perceived level of protection and the actual level of protection. There is currently an abundance of helmeteers who believe that a helmet will save your life, and are prepared to take a broken helmet as the ultimate proof. You might say that they hold these truths to be self evident, in as much as there is never any reason to question them. Helmets save lives, and that might as well be a fact as far as they are concerned. If "my helmet saved my life" actually means saved me from a bit of a graze and a bump on the head then it is hardly going to be the kind of sexy cutting edge research that gives a massive boost to helmet sales.

The case on helmets was arguably closed some time ago, there is a reasonable weight of evidence to show that overall they provide no net benefit to cyclists. However, if you wanted to obfuscate and divert attention away from genuinely useful safety measures you would probably find that you could present the no net benefit findings as inconclusive studies which should be repeated until they provide a more socially acceptable result.

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Re: Do the helmets in accidents involving helmets get investigated?

Postby pjclinch » 17 Apr 2018, 4:22pm

mjr wrote:
pjclinch wrote:
mjr wrote:If all users actually strapped the helmet on tightly enough for it not to move around, you might have a point, but many of them really do seem to have difficulty keeping the helmet steady on top of their head...


I've never seen anyone have difficulty keeping a lid on their head, and that's in the context of a Bikeability instructor where there's been years of hilariously mis-fitted examples.

I've highlighted the missing word which means the reply didn't actually refute the claim.


Okay, I've never seen anyone have difficulty keeping a lid steady on their head, and that's in the context of a Bikeability instructor where there's been years of hilariously mis-fitted examples.

mjr wrote:
pjclinch wrote:I'm no fan of helmets but demonising them with obvious non-sequiturs really doesn't help anybody.

On the one hand, demonising non-wearers is widespread and I don't think logic is working, so let's make fun of strapping a chamber pot to one's head! On the other hand, I think you're blowing a parenthetical "I'm always reminded of" out of all proportion by misinterpreting it a strict analogy instead of a visual similarity.


It wasn't that I thought it was meant to be a strict analogy, more that it isn't any sort of analogy whatsoever. The two things just don't have anything much in common aside from the involvement of a head.

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Re: Do the helmets in accidents involving helmets get investigated?

Postby pjclinch » 17 Apr 2018, 4:45pm

horizon wrote:I was hoping for some investigative evidence relating to a helmet actually used in an accident and/or conversely an accident not involving a helmet. My presumption is that minor accidents don't get investigated at all but I'm wonderting if it is these accidents where the best evidence might lie: yes, you had a fall, no you weren't injured: but why not?

Even if it is purported to be shown in some other way that helmets prevent minor injury but especially if no such evidence is currently available for serious injury, I personally would conclude that helmets are effectively useless.


The issue not that there isn't any evidence or investigation, but that the evidence and investigation doesn't produce clear, consistent and reproducible results. So what Ben Goldacre describes as "the complex contradictory mess of evidence on the impact of bicycle helmets" gives us this kind of issue:

This finding of “no benefit” is superficially hard to reconcile with case-control studies, many of which have shown that people wearing helmets are less likely to have a head injury. Such findings suggest that, for individuals, helmets confer a benefit. These studies, however, are vulnerable to many methodological shortcomings. If the controls are cyclists presenting with other injuries in the emergency department, then analyses are conditional on having an accident and therefore assume that wearing a helmet does not change the overall accident risk. There are also confounding variables that are generally unmeasured and perhaps even unmeasurable. People who choose to wear bicycle helmets will probably be different from those who ride without a helmet: they may be more cautious, for example, and so less likely to have a serious head injury, regardless of their helmets.


horizon wrote:(BTW I'm quite astonished that no such investigations take place and I feel confident that this forum would know of such studies had they occurred).


As noted, there are plenty of them. If only they agreed with one another...

As Goldacre and Spiegelhalter conclude:
In any case, the current uncertainty about any benefit from helmet wearing or promotion is unlikely to be substantially reduced by further research. Equally, we can be certain that helmets will continue to be debated, and at length. The enduring popularity of helmets as a proposed major intervention for increased road safety may therefore lie not with their direct benefits—which seem too modest to capture compared with other strategies—but more with the cultural, psychological, and political aspects of popular debate around risk.


If you want to consider "useful" as being the same as "giving me a significantly reduced risk of a trip to A&E" then what we know is... that we don't really know. The best description I've seen on helmet efficacy changing risk of "normal" cyclists is "about zero, plus or minus error bars". For non-normal cyclists, i.e., sporting, there's not actually much in the way of data. Too few hospital admissions and data not routinely collected as so much is off-road, plus numbers are relatively small.

It's worth noting that they were developed as an improvement on the racer's hairnet (a low benchmark) rather than to do a specific job. They were not designed with the fundamental point of saving commuters or similar from fatal head injury.

Wanlock Dad wrote:I think that the source of the problem is basically the discrepancy between the perceived level of protection and the actual level of protection.


It's my feeling that that's a significant chunk of it.

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Re: Do the helmets in accidents involving helmets get investigated?

Postby thirdcrank » 17 Apr 2018, 4:56pm

It's a remarkable case study of profitably marketing something without much active marketing in the sense of direct advertising especially of claims made for benefits through use. There are various techniques here including product placement and discreet political lobbying.

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Re: Do the helmets in accidents involving helmets get investigated?

Postby The utility cyclist » 17 Apr 2018, 6:19pm

There should definitely be more tests done on people on foot and motorists wearing helmets, I mean if the data is supposedly valid for people on bikes then the thousands of lives and almost hundreds of thousands of serious injuries and probably well over a million minor head injuries would be wiped off the stats thus saving the NHS billions and many families heartache ...one life saved after all :roll:

I think it's rather telling that for something pushed so hard by certain organisations and government at all levels (including the EU) as a safety intervention that they don't do more in depth studies, given the pretty much nil effect on overall safety despite others shouting it saves thousands of lives you'd want to know more surely? As per another comment, why not full sized body crash tests for all types of scenarios and indeed for all types of activities.
Last edited by The utility cyclist on 18 Apr 2018, 4:17pm, edited 1 time in total.

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Re: Do the helmets in accidents involving helmets get investigated?

Postby Vorpal » 17 Apr 2018, 10:27pm

horizon wrote:Vorpal, mjr: many thanks for that. The kind of information i thought might be available is of the forensic kind - speed of impact, what injury and why, effect on helmet etc. None of this is rocket science and I would have thought, given the high profile given to helmets, someone might have done it either to prove the case overall or to demonstrate the superiority of their own brand.

For me this is a bit of an epiphany: if the evidence doesn't exist then I think the case on helmets is effectively closed.


https://www.ncbi.nlm.nih.gov/pubmed/26974030
If you don't have access, there is a partial summary https://www.kth.se/en/forskning/artikla ... r-1.636065

One of the authors specialises in incident reconstruction finite element analysis. He's done similar work for motor vehicle crashes.

I think there is another study, with a couple more crashes analysed and more details about each crash scenario, but I haven't been able to find it today.
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Re: Do the helmets in accidents involving helmets get investigated?

Postby horizon » 17 Apr 2018, 10:45pm

Here's one of the abstracts (my emphasis):

Abstract

Cycling is a popular form of recreation and method of commuting with clear health benefits. However, cycling is not without risk. In Canada, cycling injuries are more common than in any other summer sport; and according to the US National Highway and Traffic Safety Administration, 52,000 cyclists were injured in the US in 2010. Head injuries account for approximately two-thirds of hospital admissions and three-quarters of fatal injuries among injured cyclists. In many jurisdictions and across all age levels, helmets have been adopted to mitigate risk of serious head injuries among cyclists and the majority of epidemiological literature suggests that helmets effectively reduce risk of injury. Critics have raised questions over the actual efficacy of helmets by pointing to weaknesses in existing helmet epidemiology including selection bias and lack of appropriate control for the type of impact sustained by the cyclist and the severity of the head impact. These criticisms demonstrate the difficulty in conducting epidemiology studies that will be regarded as definitive and the need for complementary biomechanical studies where confounding factors can be adequately controlled. In the bicycle helmet context, there is a paucity of biomechanical data comparing helmeted to unhelmeted head impacts and, to our knowledge, there is no data of this type available with contemporary helmets. In this research, our objective was to perform biomechanical testing of paired helmeted and unhelmeted head impacts using a validated anthropomorphic test headform and a range of drop heights between 0.5 m and 3.0 m, while measuring headform acceleration and Head Injury Criterion (HIC). In the 2 m (6.3 m/s) drops, the middle of our drop height range, the helmet reduced peak accelerations from 824 g (unhelmeted) to 181 g (helmeted) and HIC was reduced from 9667 (unhelmeted) to 1250 (helmeted). At realistic impact speeds of 5.4 m/s (1.5 m drop) and 6.3 m/s (2.0 m drop), bicycle helmets changed the probability of severe brain injury from extremely likely (99.9% risk at both 5.4 and 6.3 m/s) to unlikely (9.3% and 30.6% risk at 1.5 m and 2.0 m drops respectively). These biomechanical results for acceleration and HIC, and the corresponding results for reduced risk of severe brain injury show that contemporary bicycle helmets are highly effective at reducing head injury metrics and the risk for severe brain injury in head impacts characteristic of bicycle crashes.


Any comments would be appreciated.
When the pestilence strikes from the East, go far and breathe the cold air deeply. Ignore the sage, stay not indoors. Ho Ri Zon 12th Century Chinese philosopher