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You really should wear a helmet on your bicycle

By johnboy - 7 May 2013 53

Bike helmets: an emergency doctor’s perspective

By Michael Dinh

For those working on the frontline of trauma care, the findings of a report into the protective effects of helmets in cyclists and motorcyclists published in the Medical Journal of Australia last week come as no surprise.

When an ambulance arrives at an emergency department with a cyclist injured on the road, a clinician needs to first know a few important details. How old is the patient? What are the vital signs? And finally … were they wearing a helmet?

That’s because ambulance officers, doctors and nurses have known for a long time that if a helmet is not being worn at the time a head strikes the road, pavement or cycleway, the chances of severe head injury are much higher.

Now this been shown in a one-year study I conducted, with two colleagues, of injured cyclists and motorcyclists presenting to seven major trauma centres in Sydney.

The risks of severe head injury were more than five times higher in cyclists not wearing a helmet compared to helmeted ones, and more than three times higher in motorcyclists not wearing a helmet at the time of injury.

Severe head injuries were defined as any with significant brain haemorrhage, complex skull fracture or brain swelling.

Some 70% of such patients end up on a ventilator in intensive care units; many patients with severe head injuries are left with permanent brain damage.

It’s estimated that each new case of severe brain injury costs Australia A$4.5 million.

But it’s the things that can’t be calculated that are perhaps more crippling – the long-term personality changes, the seizures, the post-traumatic adjustment, and the interminable stress on family and carers.

helmets

judy_and_ed

Conflicting studies

Australia is one of the few countries in the world with mandatory helmet laws protecting both motorcyclists and pedal cyclists.

While helmet use in motorbike riders is generally accepted, compulsory helmet laws have been resisted by many experts.

Many argue that helmet use simply deters people from dusting off their two wheelers and pedalling their way to better health.

Using a telephone survey, Professor Chris Rissel from the University of Sydney concluded that cycling rates could increase dramatically if mandatory helmet laws in Sydney were repealed.

In contrast, a recent National Heart Foundation survey showed that overall road safety, road speed and the presence of dedicated bike paths were the main obstacles limiting bicycle use.

Only 17% of respondents identified helmet use as a potential factor.

Turning the tables on rotational injury

Publicised court cases testing Australian helmet laws have even invoked limited autopsy reports hypothesising the effect of helmets imparting “rotational forces” on the brain, causing diffuse axonal injury.

Diffuse axonal injury is widespread (rather than focused) damage to the brain, and is one of the major causes of unconsciousness and persistent vegetative state following head trauma.

The argument here is helmets apparently exacerbate head injury severity by causing the head to twist quickly on impact, thus creating rotational forces on the brain.

There have been no controlled studies in the clinical setting into the association between helmet use and diffuse axonal injury – until now.

We found no reports of diffuse axonal injury in pedal cyclists, helmeted or non-helmeted, and only a marginal increase in such diagnoses in non-helmeted motorcyclists.

Definitely worth helmet hair

This Sydney-based study was the first to place motorcyclists and pedal cyclists side by side and demonstrated that the protective role of helmets in both groups are important – and even better in pedal cyclists.

Helmet hair is a small price to pay for protection. mrlerone

These results are within the range reported by a Cochrane Collaboration systematic review on the subject as well as a study of more than 13,000 pedal cyclists in France published in 2012.

Some experts against this type of observational research cite small sample sizes, and flaws inherent in case control studies, such as not being able to take into account factors such as speed and intoxication.

But it is also true that the very same type of observational study designs was the basis on which the association between smoking and lung cancer was first described.

Once you get enough studies pointing in the one direction, the signal becomes harder to refute.

If mandatory helmets are good enough for motorcyclists, they’re certainly good enough for pedal cyclists.

And as more and more people use bicycles to go to work, work up a sweat or just spend time with the kids, they can rest assured that the helmet resting comfortably on their head is doing something much more than simply disrupting their hairdo.

Michael Dinh does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.

The Conversation

This article was originally published at The Conversation.
Read the original article.

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53 Responses to
You really should wear a helmet on your bicycle
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keithjanderson 2:26 pm 16 May 13

Some other studies into wearing helmets (easy to find with Google) are here:
http://www.vicroads.vic.gov.au/Home/SafetyAndRules/SaferRiders/BikeRiders/WearingABicycleHelmet.htm, and a 2012 paper here from Uni of NSW:
http://www.bicyclenetwork.com.au/media/vanilla/file/Uni%20NSW%20-%20Helmets.pdf

Risk Management discipline has concepts of Likelihood and Consequence. Wearing a helmet is about reducing consequence – reducing damage to brain and head.

FXST01 9:26 pm 11 May 13

neanderthalsis said :

” I look daft in a helmet” is an incredibly lame excuse for not riding.

Only if you have those god-awful zip ties poking out of the top.

Aeek 2:23 pm 11 May 13

beedlebum said :

we get the silly kids that ride around with their helmet hanging off their handlebars

That’s wearing the helmet on their bicycle (see the subject!). I think if you are going to wear a helmet, you really should wear it on your head.

beedlebum 8:23 am 11 May 13

Keep the laws compulsory.

If we (the adults) are all wearing helmets, then we’re all being good role models for kids who need to wear helmets while they’re learning to ride safely and they’re all wobbly. If we instead show them that helmets are ‘optional’, then we get the silly kids that ride around with their helmet hanging off their handlebars or unbuckled. They then get seriously injured (due to youthful silliness and inexperience).

Won’t someone please think of the children??!

howeph 12:30 pm 08 May 13

Mathman said :

howeph said :

My point is that the likelihood is so small (about the same as walking in this case) that there is no need for the marginal mitigation effect that a helmet offers. Certainly no where near enough to make it unlawful and to fine poor old Granny.

Your argument is so full of holes.

Firstly, as the study shows, wearing a helmet has a significant mitigation effect of reducing head trauma should you have an accident resulting in a trip to the hospital. The risk might be small but the outcome can be vastly different.

Hi Mathman. Thanks for joining the debate. Unfortunately I think that it is your argument that is full of holes, not mine.

Firstly, I don’t disagree with anything in your opening argument. The key point however, that I don’t think you’ve grasped, is the “should you have an accident resulting in a trip to the [major trauma centre]” bit.

As I said in my earlier post: “Public health policy should not be based on studies conducted on very select populations – in this case only seriously ill patients arriving at major trauma centres.”

This study suffers from extreme selection bias. When you consider the millions? of individual trips (don’t forget all those kids riding in the park) people make by bike every year, in the vast number of those cases, wearing a helmet had precisely zero effect on reducing head trauma. They didn’t fall off. They weren’t hit by a car.

The fact is that riding a bike, in most cases, is a very safe activity. I understand that many people disagree with this statement, but whilst they are entitled to their own opinions they aren’t entitled to their own facts. The following sports all result in more hospitalistions per the same number of participants: Motor Sports, Roller Sports, Australian Rules Football, Horse Riding, Rugby League, Netball and Cricket. [source: http://www.nisu.flinders.edu.au/pubs/reports/2006/injcat79.php%5D

Mathman said :

Secondly, you are falling for the ecological fallacy – assuming that your individual characteristic can be inferred from the population’s characteristic. For example, if the rate of serious head trauma accidents in the population is, say, 1 in every 10,000 bicycle trips, then it is a mistake to conclude that an individual therefore has a 1 in 10,000 chance of having a serious head trauma accident on any particular trip.

Thanks, I hadn’t heard of the “Ecological fallacy” and so I had to look it up. But I don’t see that I have fallen for it, quite the opposite in fact. I am not arguing that if the trauma accidents rate is 1 in 10,000 that any particular trip has a 1 in 10,000 chance. But I am saying that the average chance of all trips is very low (1 in 10,000 if we use your numbers). I freely admit that each trip is different. Take the example you quoted above of Granny going to the shops on her bike – extremely low risk, lower than the already low average risk. Hence a blanket law is pointless.

Mathman said :

Likewise, it is also a mistake to say that the risk of an individual having a serious head trauma accident is so low as to be insignificant therefore the incidence in the population must also be insignificant.

I agree. Please show where I have made that claim.

Mathman said :

The policy makers who develop these policies really don’t care about the individual – its a (relatively) free country and you can smack your head into the bitumen if you so desire. What they are concerned about is the population as a whole, and particularly the cost to the population of individual actions. In this case, it is the $4.5 million cost of each serious head trauma injury. For the cases included in the sample, if they had all been wearing a helmet then 15 head injuries may have been prevented, potentially saving the population $67 million. That buys a lot of $20 helmets.

Well obviously in this context I strongly disagree that we are a “free country”. But I do agree that policy makers should be looking at the population as a whole. That’s why I said “”Public health policy should not be based on studies conducted on very select populations”.

In this case mandatory helmet laws are bad policy.

1) They provide a very marginal benefit to public safety and health costs. Given your figure of $67 million compared to the NSW health budget for 2012-13 of 18.3 billion that represents just 0.003% of the health budget.

2) They do however create a very significant costs to society. – namely the reduction in the participation rate and the flow on health benefits of exercise (treatment of heart disease is I think the biggest health cost?), reduced pollution and carbon emissions.

DrKoresh 11:36 am 08 May 13

Canberroid said :

pink little birdie said :

Considering the helmet laws have been in the entire life of gen y there isn’t really any excuse for them not wearing helmets.

Gen Yers have the exact same excuses as everyone else (plus the excuse that you old farts didn’t have to wear helmets when you were young so why should we).

Plenty of posts here have assumed that people don’t like helmets because of appearance. I don’t wear a helmet for short trips around my neighbourhood because it’s so much more comfortable and pleasant without it. If I’m riding down northbourne I’ll put it on. It should be my choice though.

I completely agree with you. I haven’t been able to find a helmet that fits my head since I became a teenager, which is why I never wore one on the rare occasions where I would ride a bike (usually a mate’s). I’m a total gumby when it comes to co-ordination though so I never used to ride on the road or at any great speed.

Once we move somewhere that’s a bit nearer to anywhere I might get myself a bike. does anyone have helmet advice for big-heads like me?

Canberroid 1:46 am 08 May 13

pink little birdie said :

Considering the helmet laws have been in the entire life of gen y there isn’t really any excuse for them not wearing helmets.

Gen Yers have the exact same excuses as everyone else (plus the excuse that you old farts didn’t have to wear helmets when you were young so why should we).

Plenty of posts here have assumed that people don’t like helmets because of appearance. I don’t wear a helmet for short trips around my neighbourhood because it’s so much more comfortable and pleasant without it. If I’m riding down northbourne I’ll put it on. It should be my choice though.

Mathman 12:31 am 08 May 13

howeph said :

My point is that the likelihood is so small (about the same as walking in this case) that there is no need for the marginal mitigation effect that a helmet offers. Certainly no where near enough to make it unlawful and to fine poor old Granny.

Your argument is so full of holes.

Firstly, as the study shows, wearing a helmet has a significant mitigation effect of reducing head trauma should you have an accident resulting in a trip to the hospital. The risk might be small but the outcome can be vastly different.

Secondly, you are falling for the ecological fallacy – assuming that your individual characteristic can be inferred from the population’s characteristic. For example, if the rate of serious head trauma accidents in the population is, say, 1 in every 10,000 bicycle trips, then it is a mistake to conclude that an individual therefore has a 1 in 10,000 chance of having a serious head trauma accident on any particular trip. Likewise, it is also a mistake to say that the risk of an individual having a serious head trauma accident is so low as to be insignificant therefore the incidence in the population must also be insignificant.

The policy makers who develop these policies really don’t care about the individual – its a (relatively) free country and you can smack your head into the bitumen if you so desire. What they are concerned about is the population as a whole, and particularly the cost to the population of individual actions. In this case, it is the $4.5 million cost of each serious head trauma injury. For the cases included in the sample, if they had all been wearing a helmet then 15 head injuries may have been prevented, potentially saving the population $67 million. That buys a lot of $20 helmets.

pink little birdie 10:52 pm 07 May 13

Considering the helmet laws have been in the entire life of gen y there isn’t really any excuse for them not wearing helmets. and really if people ride to work and put the effort into changing at work taking a hair brush to work is natural (also women I know keep hair brushes at their desk even if they don’t ride).
I have a pink helmet and wouldn’t ride without it.

neanderthalsis 9:25 pm 07 May 13

” I look daft in a helmet” is an incredibly lame excuse for not riding and I would question the credibility of any research that cited that as a legitimate reason for non-participation. It’s like “I’d take the bus more but I don’t like the bus loonies” or “I’d go for a jog but it is cold and dark”. Lame excuses given by people looking for a reason not to do something.

IrishPete 8:49 pm 07 May 13

I think I have read fairly solid evidence that helmet laws decreased participation rates. So the safety benefits of helmets have to be offset by the health effects of fewer people riding bicycles (and more driving cars). I’m not sure what that equation adds up to – overall positive effect or overall negative effect. Obviously the outcomes are quite different – dramatic head injuries compared with widespread diffuse increases in illnesses related to poor fitness and greater emissions from cars.

Certainly I’d be happier being able to legally potter down to the shop on a bicycle without a helmet, because the risk is low (due to the short exposure time), whereas it’s probably wise to wear a helmet when riding longer distances.

I don’t have hair, so the helmet also protects me from sunburn.

IP

Felix the Cat 8:37 pm 07 May 13

Masquara said :

It’s all very well to say helmet hair doesn’t matter – but in the workplace I’m afraid it does, at least for women.

Doesn’t the wind mess up your hair when riding sans-helmet? Don’t you own or know how to use a brush or comb?

Another non-reason for not wanting to wear a helmet.

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