Searching for statistics and studies

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AdamS
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Searching for statistics and studies

Postby AdamS » 26 Sep 2017, 2:12pm

Hello,

I am writing a summary of the helmet debate, mainly just so I don't have to write out the arguments afresh every few weeks when someone I know posts some graphic helmet promtion meme on social media. I think I mostly have it covered but I am struggling to find some statistics to help me put the risks of cycling and potential benefits of helmets in perspective.

Specifically, does anyone know if data about the proportion of fatalities/ serious head injuries sustained by helmeted cyclists has ever been published for the UK?

More generally, can anyone recommend a relatively recent review (or reviews) of literature regarding helmet efficacy? Not a cherry-picked list from a pro- or anti-helmet site though please.

As a veteran reader of the sub-forum I am very well aware of the helmet arguments so I would very much like for this thread not to rehash those.

Thanks,

Adam

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meic
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Re: Searching for statistics and studies

Postby meic » 26 Sep 2017, 2:22pm

Not a cherry-picked list from a pro- or anti-helmet site though please.


Is that possible?

Normally one would expect to be able to trust impartial bodies like the transport authorities and road safety research establishments, or even the British Medical Association. But on the whole helmet skeptics refute their announcements.

On the other hand the world's leading risk analysis scientist says they make no statistically significant difference, so the helmet supporters dismiss his status as impartial.
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Re: Searching for statistics and studies

Postby Steady rider » 26 Sep 2017, 4:49pm

http://worldtransportjournal.com/wp-con ... eb-opt.pdf

It is a long paper, pages 8 to 35, but fairly recent. It links to about 40+ reports. Only about 3 from 40 related to fatalities.

AdamS
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Re: Searching for statistics and studies

Postby AdamS » 26 Sep 2017, 6:41pm

meic wrote:
Not a cherry-picked list from a pro- or anti-helmet site though please.


Is that possible?

Possibly not and even an impartial summary is subject to biases in the studies themselves. I just wanted not to be directed to selective lists of evidence compiled by campaigners such as BHIT or cyclehelmets.org

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Re: Searching for statistics and studies

Postby Steady rider » 26 Sep 2017, 7:23pm

Please let us know what you find.

ps a starting point perhaps
A 2015 report, ‘Overestimation of the effectiveness of the bicycle helmet by the use of odds ratios’ details;
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.
Refer;
http://www.fietsberaad.nl/?lang=nl&repo ... dds+ratios

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mjr
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Re: Searching for statistics and studies

Postby mjr » 27 Sep 2017, 1:09pm

AdamS wrote:Specifically, does anyone know if data about the proportion of fatalities/ serious head injuries sustained by helmeted cyclists has ever been published for the UK?

Proportion relative to what? All cyclists? Similar non-motorised casualties? Historic trends of either?

Helmet-wearing or not is in the casualty variables in police collision reports (STATS19, described by STATS20 2011 Annex 3 section 3.20) but it doesn't appear to be published in the Reported Road Casualties of GB data. You might be able to request it under Freedom of Information, or at least some summary of it.

But it's got serious flaws in that it records an incorrectly-worn helmet the same as no helmet - I suspect that an incorrectly-worn helmet is probably worse than no helmet at all, giving most of the drawbacks with none of the impact protection. I guess whoever chose that coding was a helmet-supporter!

Secondly, the collision reports don't say what the injury was, so you can't distinguish a head injury from another serious injury or cause of death from that data.

Finally, you're dealing with a small subset (maybe 30% helmet-using) of an already fairly small number of 100 deaths a year (2015), plus there's many dilemmas about what you include - do you include deaths from multi-vehicle collisions which helmets are not designed for but may have influenced? Do you include those from non-head-injuries based on the theory that motorists treat helmet-users differently, such as being more likely to attempt a close pass which might go wrong?

In the end, it might be informative but will it really tell us anything more than we already know from the historic lack of correlation between changes in helmet usage level and cycling casualties?
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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Re: Searching for statistics and studies

Postby AdamS » 27 Sep 2017, 2:12pm

Thank you Steady Rider; two very useful links.

You are absolutely right mjr. My reason for wanting those figures was that many graphic helmet promotions use statistics with the implication or explicit statement that almost all are preventable. It appears that this is the view held by most people who have never looked into the matter. If this notion was immediately dismissable by showing helmet-wearers to be a significant proportion of fatalities/serious head injuries it might convince them that the issue is more complicated and worth reading about in more detail. I know that we can do significantly better with the statistics at our disposal but it helps to have something which initially draws people to read.

Helmet promotion often also conflates figures for 'serious injury' with 'serious head injury of the kind a helmet might prevent' which is disingenous. If possible, as well as putting the risks of cycling in perspective (per-mile risk of fatality comparible to pedestrians, safer than many other activities, health benefits of cycling etc etc.) we should also try to set more realistic estimates for the proportion of serious injuries which are of a kind a helmet is designed to protect against.

For your information, this was the most-recent and particularly dishonest social media meme which got my hackles up and really convinced me that we need to challenge this stuff wherever we see it:
Tripe.jpg

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mjr
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Re: Searching for statistics and studies

Postby mjr » 27 Sep 2017, 2:41pm

AdamS wrote:If this notion was immediately dismissable by showing helmet-wearers to be a significant proportion of fatalities/serious head injuries it might convince them that the issue is more complicated and worth reading about in more detail.

Why would it? That graphic you cite has been doing the rounds for years, a helmet-supporting zombie. It's been debunked a few times and the captions are a mixture of misdirection and outright lies, mixed with emotion. What little accurate statistical content it has isn't British - under 2000 people a year die in reported road collisions here.

I feel what's needed is an emotional response: call its makers f****** liars, suggest they're stealth-funded by helmet-manufacturers and motoring lobbyists and ask whoever shares it why they want to scare people into cycling less: are they evil or have they been tricked? :twisted:

[...] we should also try to set more realistic estimates for the proportion of serious injuries which are of a kind a helmet is designed to protect against.

Not sure about serious injuries, but you can make some estimates for fatalities by categorising the likes of Bez's excellent http://beyondthekerb.org.uk/casebook/ into maybe/unlikely/unknown. I think the last time I tried that, it was 1 maybe a year with the rest split between unlikely (mostly motor vehicle collisions and things like heart attacks) and unknown (bike-only falls with no external injury reported).

But I remain of the opinion that those sharing helmet-promoting images based on emotional blackmail will not respond to more accurate statistics. I've tried that before and it's never worked - it has had minimal effect on government, but even there it's a tough sell. So use emotion: you can try quotes like Chris Boardman's "In an incident with a car they will have almost no effect" and "it's not in the top ten things that you can do to keep safe" but sometimes it's better just to ridicule them, such as pointing out that that exact same image with the exact same wording is an argument for helmets for all road users, including drivers, passengers and even people walking!

Or just post an image asking if that's all they're doing and if so, they're doing this:
Image
(from https://twitter.com/beztweets/status/884166041462505478 )
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Re: Searching for statistics and studies

Postby pjclinch » 27 Sep 2017, 3:41pm

Rather than reinvent the wheel I usually quote a couple that mirror the time and considerable effort I've spent over the years on this. I don't agree with them because of who wrote them or I like the cut of their jibs, I agree with them because they came to pretty much the same conclusions I did independently of them. If you do want to go back to the drawing board you need to follow the primary references and you'll need to give weeks to months over to it. Frankly, it isn't worth the bother.

There's Tim Gill's 2005 Cycling and Children and Young people which is a consultancy paper for a children's charity National Children's Bureau. The whole thing is 53 pages, but the Annex covers pages 31 to 48 and concerns itself with the helmet debate. As it notes, it isn't a systematic literature review but it does demonstrate quite well that there's lots of evidence and much of it is in stark disagreement, and different approaches by different bodies and those are in disagreement too. It's not stated as such, this is my inference, but the effective conclusion is it's all too messy to draw a nice black and white conclusion.

And there's Ben Goldacre and David Spiegelhalter's BMJ editorial Bicycle Helmets and the Law which points out the obvious questions we want to know the answers to, and goes on to say that it turns out to be very difficult to get the answers, so nice black and white conclusions aren't really going to happen. It finishes with the following:
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.

My inference again, but that looks to me like it's mainly down to rather fuzzy, arm-wavey things more than it is about how good helmets actually are or aren't, which turns out to be hard to pin down.

In this environment anyone claiming surety where evidence hawks like Goldacre and the Winton Prof. of Public Understanding of Risk are saying stuff which comes across as, well, actually it's all rather complicated, is probably laying out their stall with rather more faith than fact. And that really isn't a sound basis for public policy interventions. And it's not a great environment to go on a research spree either, but do go ahead if you really want. You'll need a proper research library though, a web browser on its own is not enough.

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Mick F
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Re: Searching for statistics and studies

Postby Mick F » 27 Sep 2017, 4:08pm

Cultural
Psychological
Political.

Seems those three things dictate everything.
Mick F. Cornwall

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Re: Searching for statistics and studies

Postby Steady rider » 27 Sep 2017, 7:06pm

It probably needs new research that could help in certain aspects. To start with looking into measurable helmet effects in more detail, these are pre impact situations. Next may be a fuller assessment of risk from head and other injury per km travel and in various types of situation, e.g, main roads, traffic density, road and driving cultures, a wide mix of circumstances. Understanding how the risks can be reduced by various approaches. Convenience aspects to helmet wearing and how people view the need or not for wearing helmets. Impact of helmet laws and promotion.
Overall health aspects of cycling v impact from helmet laws. Degree of enforcement with helmet laws. Legal issues comparing accident compensation for non-helmeted cyclists v pedestrians or other road users. Human rights of the individual to make their own choice based on the level of evidence relating to a safety product or what may be a product that reduces safety. Complicated yes.

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Re: Searching for statistics and studies

Postby axel_knutt » 27 Sep 2017, 9:35pm

Steady rider wrote:It probably needs new research

Or even just a repeat of some rather old research.
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Re: Searching for statistics and studies

Postby Cunobelin » 28 Sep 2017, 6:18am

AdamS wrote:Thank you Steady Rider; two very useful links.

You are absolutely right mjr. My reason for wanting those figures was that many graphic helmet promotions use statistics with the implication or explicit statement that almost all are preventable. It appears that this is the view held by most people who have never looked into the matter. If this notion was immediately dismissable by showing helmet-wearers to be a significant proportion of fatalities/serious head injuries it might convince them that the issue is more complicated and worth reading about in more detail. I know that we can do significantly better with the statistics at our disposal but it helps to have something which initially draws people to read.

Helmet promotion often also conflates figures for 'serious injury' with 'serious head injury of the kind a helmet might prevent' which is disingenous. If possible, as well as putting the risks of cycling in perspective (per-mile risk of fatality comparible to pedestrians, safer than many other activities, health benefits of cycling etc etc.) we should also try to set more realistic estimates for the proportion of serious injuries which are of a kind a helmet is designed to protect against.

For your information, this was the most-recent and particularly dishonest social media meme which got my hackles up and really convinced me that we need to challenge this stuff wherever we see it:
Tripe.jpg





Actually I like that one

It does not mention the word "cyclist" and by including ALL head injury sufferers addresses the big Elephant of the fact that wider helmet use could prevent far more injuries

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Re: Searching for statistics and studies

Postby Cunobelin » 28 Sep 2017, 6:54am

I find the simple reply is to point out that in Cohort Studies, cyclists are a minority, and whether they believe that helmet use should be expanded to pedestrians, especially the elderly and young

For many years the Thudguard child helmet has served well for this when the subject of helmets for child arises

Image

It is so easy to use every single pro-helmet argument to question whether child is not wearing one

For instance Headway uses the British Association for Accident and Emergency Medicine asa reference for supporting helmet use.... they also support the Thudguard

Why should we act upon their support in one case and ignore it in the other?

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Re: Searching for statistics and studies

Postby Steady rider » 28 Sep 2017, 8:47am

Dinh et al 2015 study provided data showing 62% of helmeted v 41% of none wearers had upper limb injuries, similarly for McIntosh et al 2013, 26% v 16%, see pages 10 and 17, 'Weaknesses with a meta-analysis approach to assessing cycle helmets'. Feb 2017
http://worldtransportjournal.com/wp-con ... eb-opt.pdf

pages 28/29 refers to;
A)
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).[i]

page 29 refers to;
B)
Robinson 1996 also refers to the incidence of hitting their head/helmet in a cycling accident was "significantly higher for helmet wearers (8/40 vs 13/476, i.e. 20% vs 2.7%, p 0.00001)". A bare head width of approximately 150mm may avoid contact compared to a helmeted head at approximately 200mm width. Helmet wearers often report hitting their helmets and the 7 fold increase may have long term effects that may not show up in a meta–analysis.

page 29 refers to;
C)
Erke and Elvik 2007[i] examined research from Australia and New Zealand and stated: "There is evidence of increased accident risk per cycling-km for cyclists wearing a helmet. In Australia and New Zealand, the increase is estimated to be around 14 per cent." The findings were based on six reports, four from when legislation was in place.

page 29 refers to;
D)
A recent report detailed that cyclists wearing helmets had more than twice the odds of suffering an injury than cyclists not wearing helmets, (104) with an OR value 2.81, 95% CL =1.14, 6.94.

104 Porter AK, Salvo D, Kohl HW, Correlates of Helmet Use Among Recreation and Transportation Bicyclists, AJPM 2016. https://www.ncbi.nlm.nih.gov/pubmed/27866599

The above information provides evidence of helmet wearers incurring a higher accident rate, per cycling kilometre or in comparison to non-wearers or as helmet use increased in proportion.

E)
Another evaluation, published by the New Zealand Medical Journal, detailed;

Injury data11 for 2006–09 compared to 1998/90 shows an average reduction of approximately 18.5% (858/1052), compared to cycling reducing by 38.5% (24/39 million hours). The approximate risk per million hours cycling therefore increased from 27 to 35.7 or by 32%.

Refer to https://www.nzma.org.nz/journal/read-th ... cle-clarke

F)
A 2015 report, ‘Overestimation of the effectiveness of the bicycle helmet by the use of odds ratios’ details;
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.
Refer;
http://www.fietsberaad.nl/?lang=nl&repo ... dds+ratios

G)
Page 20 of ‘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, details;
4) Robinson's 1996 report provided injury data for children. In Victoria, the equivalent number of injuries for pre law levels of number of cyclists increased by 15% from 1990 to 1992. Robinson provides data in Table 2 for children in NSW. The equivalent number of injuries increased from 1310 (384 head + 926 other injuries) pre law in 1991 to 2083 (488 head + 1595 other injuries) in 1993. The relative injury rate increased by 59% from 1310 to 2083. The relative increase in 'other' injuries of 72% and 27% for 'head' raises serious concerns. The proportion of head injuries decreased from 29.3% to 23.4% and would give the impression of a benefit if viewed in isolation.

H)
The report, ‘The Case against bicycle helmets and legislation’, Velo City Confernece paper, Munich, 2007.
http://www.ta.org.br/site/Banco/7manuai ... helmet.pdf
Details some of the potential positive and potential negative aspects of wearing a helmet, two potential benefits are listed compared with 13 potential disadvantages. A number of reports are listed A1 to A14 indicating a higher accident rate associated with wearing helmets.

From the above information it appears that helmet use and a higher accident rate are connected. If a higher fall rate occurs for helmet users then this affects the proportion of head and other injuries. Most research to date has overlooked to a degree the essential issue of the fall rate for both groups and consequence.

The UK's National Children's Bureau (NCB) provided a detailed review in 2005 stating "the case for helmets is far from sound", "the benefits of helmets need further investigation before even a policy supporting promotion can be unequivocally supported" and "the case has not yet been convincingly made for compulsory use or promotion of cycle helmets".

The Cyclist Touring Club (Cycling UK national cycling charity) states that "Individuals should be free to make their own decisions about whether or not to wear helmets, with parents making these decisions in the case of younger children. Their decisions should be informed by clear information about the uncertainties over the benefits or otherwise of helmets. ' and "it is therefore entirely possible that helmet wearing might have a net disbenefit even in safety terms (a point also suggested by some of the empirical evidence), not to mention the health and other disbenefits identified above".

Cycling UK state;
Cycling UK is opposed to both cycle helmet laws and to helmet promotion campaigns because these are almost certainly detrimental to public health. Evidence shows that the health benefits of cycling are so much greater than the relatively low risks involved, that even if these measures caused only a very small reduction in cycle use, this would still almost certainly mean far more lives being lost through physical inactivity than helmets could possibly save, however effective.