Croakey has run a series of articles this year questioning the laws requiring bicycle helmets to be worn, and the controversy has also been widely canvassed elsewhere in the media.
Sue Abbott, a longstanding cycling enthusiast, argued that the laws are misplaced, and a leading public health advocate Clinical Associate Professor Chris Rissel described the laws as “failed public policy”.
In another post, Rissel reported on research concluding that it was likely that factors other than the mandatory helmet legislation reduced head injuries among cyclists.
But those findings have been questioned by an analysis of the data by medical epidemiologist Tim Churches.
Tim Churches writes:
In August 2010, Croakey published an article titled “Let’s see what happens if we repeal the laws on bicycle helmets” by Clinical Associate Professor Chris Rissel from the School of Public Health at the University of Sydney.
In it, Rissel reported on a research paper written by himself and colleague Dr Alex Voukelatos which appeared in the August 2010 issue of the Journal of the Australasian College of Road Safety (JACRS), and which set out to examine whether the introduction of compulsory cycling helmet laws in NSW in 1991 had a measurable impact on head injury rates amongst cyclists.
From a series of four observational surveys, commissioned by the NSW Roads and Traffic Authority (RTA) and carried out in September 1990 and April of 1991, 1992 and 1993, it is known that there was an approximately 30 percent decrease in the number of observed cyclists in the the three years immediately after the cycling helmet laws came into force.
In order to adjust for this fall in the number of cyclists, Voukelatos and Rissel calculated the ratio of the number of cyclists hospitalised in NSW due to head injuries to the number of cyclists hospitalised due to arm injuries, for each financial year since 1988/89.
Their (sound) rationale for such a study design was that “…even if the number of cyclists has dropped over time, the relative injury rates (head versus arm) should remain unchanged unless some factor is differentially impacting on one type of injury – for example, helmet use reducing head injuries but not affecting arm injuries”.
They then drew a time-series graph of these head-to-arm injury ratios, plotted together with the proportions of cyclists observed to be wearing helmets as reported by the four RTA surveys. Their principal graph, as published, is shown below.
The solid lines in the graph are the ratio of head-to-arm injuries (the discontinuity around 1999/2000 is an artefact, caused by a change in the injury coding system), the dashed lines are the observed proportion of cyclists wearing helmets from the RTA surveys, and the grey bar represents the introduction of the helmet laws.
The authors wrote: “The main conclusion of this examination of the ratio of head to arm injuries over time is that there was a marked decline in head injuries among pedal cyclists before the introduction of mandatory helmet legislation and behavioural compliance, most likely a result of a range of other improvements to road safety.”
Unfortunately this graph is incorrect.
The four RTA surveys, represented by the dashed lines, were undertaken in September 1990 and April of 1991, 1992 and 1993. The sharp increase in the proportion of helmet-wearers is due to the introduction of the helmet laws.
However, inspection of these lines reveals that they are positioned on this graph about 15 months too late (i.e. too far to the right) – for example, the first point on each line corresponds to the September 1990 RTA survey, but it has been positioned on the graph half way between 1991/92 and 1992/93 financial year marks. The other points are similarly misplaced. The vertical bar representing the introduction of the helmet laws is also misplaced.
The solid line in the graph represents the ratio of head-to-arm injury hospitalisations in cyclists, and is based on numbers of head or arm injury hospitalisations for all ages, given in the main data table in the paper. The problem is that counts of hospitalisations for each age group in that table do not sum, as they should, to the totals for all ages in the same table – in other words, the numbers on which the graph is based literally do not add up, a fact which can be verified by the reader with a pocket calculator.
However, if we assume that the counts of hospitalisations for each age group as published in the main data table are correct, and that it is the totals which are wrong, then the graph above should have appeared as shown below, after recalculating the totals and ratios, and correctly plotting the data points. It must be stressed that the following graph is still based solely on the data provided by the authors in their original paper, and that data may contain other errors which cannot be detected merely by examining the published paper.
It is immediately apparent that the sharp and substantial drop in the head-to-arm injury ratio coincides exactly with the introduction of the helmet laws and the corresponding increases in the proportion of cyclists observed to be wearing helmets in the RTA surveys.
This is, of course, exactly what one would expect, given that cycling helmets have been shown to help prevent head injuries and/or reduce their severity in many other studies. It is also clear that, when correctly added up and plotted, the data which Voukelatos and Rissel provide in their paper do not support their conclusions.
These errors and other methodological considerations are described in greater detail in a letter to the editors on page 62 of the November 2010 issue of JACRS, which together with the August 2010 issue in which the original Voukelatos and Rissel paper appeared is freely available from the ACRS website.
Professor Raphael Grzebieta, Peer Review Editor of JACRS, added this editorial note to the published letter:
On the receipt of Tim Churches’ letter, a copy was sent to the authors Dr Alexander Voukelatos and A/Prof. Chris Rissel on 7 October 2010 seeking their response. A reply letter was subsequently received from the authors on 20 October 2010. Both Tim Churches’ letter and Dr Voukelatos and A/Prof. Rissel’s reply letter were sent to four independent reviewers along with the original paper. .…all reviewers unanimously indicated that Tim Churches’ letter should be published in the journal and all supported that his criticisms, his graph and comments appear valid. .…Dr Voukelatos and A/Prof. Rissel have stated in their response: ‘Tim Churches is quite correct in writing that the paper titled ‘The effects of bicycle helmet legislation on cycling related injury: The ratio of head to arm injuries over time’ has serious arithmetic and data plotting errors. We sincerely apologise for these unintentional errors and any confusion that this may generate.’
In his Croakey article about their paper, Chris Rissel called for “…a research study where the legislation is repealed in one jurisdiction (say Newcastle, or Wollongong) and the effects carefully studied over a couple of years.”
It is now clear that the Voukelatos and Rissel study provides no new impetus for the Australian cycling helmet laws to be repealed.
The ongoing effect of the cycling helmet laws, a full two decades after they were introduced, on the uptake of cycling in Australia remains unknown.
There is no doubt that after a decline in cycling participation in all developed countries throughout the second half of the 20th Century, the popularity of cycling has increased dramatically over the last decade, and can now be described as positively booming, helmet laws notwithstanding.
A recent Canadian study*, using data from a large-scale, ongoing population health survey, compared before-and-after rates of cycling in two provinces which introduced compulsory cycling helmet laws several years ago – there was no appreciable change in the numbers of people cycling after helmet laws were introduced. This may be because cycling helmets are now cheaper, more readily available, better designed and more generally accepted than they were two decades ago.
Although it is likely that some cyclists (and potential cyclists) would prefer to ride bare-headed, the critical question in 2010 is: how many people choose to not cycle because they must wear helmets? The Canadian data suggests that their number is few.
The Voukelatos and Rissel study was widely reported in the mainstream media both here and overseas at the time it was published, and it continues to be discussed in the cycling blogosphere. The fact that their findings were wrong needs to be equally widely reported.
Somewhat ironically, Chris Rissel is scheduled to present a paper to the Australian Cycling Conference, in Adelaide in January 2011, titled “A content analysis of Sydney media coverage of recent mandatory helmet legislation discussions.” It promises to be an interesting talk.
* Dennis J, Potter B, Ramsay T and Zarychanski R. The effects of provincial bicycle helmet legislation on helmet use and bicycle ridership in Canada. Injury Prevention 2010;16:219-224 [ http://www.ncbi.nlm.nih.gov/pubmed/20587815 ]
Postscript: Chris Rissel included the findings of this paper in a written submission to the recently-held NSW Parliamentary Staysafe (road safety) inquiry into vulnerable road users (motorcyclists and pedal cyclists) http://www.parliament.nsw.gov.au/prod/parlment/committee.nsf/0/BD0C30FA449977D9CA2577270021AA13.
The final report of the inquiry was released recently, and it includes a number of recommendations covering cycling accident data collection, improvements to cycling infrastructure, and better driver education and training about cyclists and their safety. Regarding cycling helmets, the report noted that “…although there are divergent positions on this issue, the majority of submissions and the bulk of evidence received by the Committee support the current mandatory use of helmets for bicycle riders”.
• Tim Churches is a medical epidemiologist with two decades of experience in the use of routinely-collected health data to evaluate public health issues. He has been an enthusiastic, although rather slow, cyclist for most of his life.
It is clear that there were basic arithmetic and data plotting errors in the original paper, and obviously this is embarrassing, but the new graph by Mr Churches uses these erroneous data. The main conclusion that there was a consistent reduction in cyclist head injuries in the 1980s and early 1990s before helmet legislation is still valid, although the revised NSW data will not show it as clearly as data from other states because they don’t go back far enough. These figures will be posted separately in a fuller response (because this comment section does not allow graphs).
I’m glad to see this article clarify these results.
For years I’ve heard this debate rattle around and experts debate the data, but as a cyclist who once bounced my scone off a kerb, I don’t need data to tell me that wearing a helmet is far safer than not.
On moving from rural Victoria to NSW 7 years ago I was amazed how few cyclists wear helmets. Any day I would see loads of kids and adults not wearing helmets – the cops don’t seem to care. In one Victorian rural city I lived in, at least two teenaged kids at the school had their lives saved (without doubt) by wearing helmets when they were dragged under trucks. In our last Victorian town the cops used to visit from some distance to do random checks on kids wearing helmets. It was a different culture. Because of the ‘non-wearing’ culture up here, I think that NSW is perhaps the wrong state to be using to draw any strong conclusions on research into the efficacy of bike helmets. I would like to see the results from a helmet wearing state like Victoria before I drew any conclusions.
Thank you Tim Churches. When seat belts and crumple zones were introduced in cars you could easily find people who, apparently without any basis in physics, believed both to be more dangerous than the alternative.
Bicycle Victoria website also has links to a Canadian study of some 44 thousand hospitalisations which, in short, says wearing helmets reduces injury.
About time this nonsense about helmets being unsafe or less safe was put to bed.
I don’t have any problem with the idea that in an accident, helmets can reduce head injuries. What I do have a problem with is the claim that helmet laws don’t discourage cycling.
The Canadian study Tim links to shows conflicting data about cycling use after helmet laws. The data in the study shows that in Prince Edward Island (where the before & after law effect was being examined), while recreational cycling increased from 16% to 24%, the number of adult trips by bike decreased by over 25%, as did children commuting. The same study also recognises that cycling in NSW and VIC decrease by over 40% in the years after mandatory helmet laws were introduced.
Mandatory helmet laws are a failure. It is an indisputable fact that the safest places to ride (Netherlands, Denmark, Germany etc) are the places with very low levels of helmet use, and that no region with mandatory helmet laws has a high cycling modal share.
Cycling safety is best served by reducing collisions with motor vehicles, not forcing people to wear styrofoam hats. Lets deal with the real problem and give people the freedom to wear helmets if they feel the need.
@SBH – it seems you may have missed the point. The original article by Rissel didn’t claim that helmets are unsafe, it claimed that mandatory helmet laws were ineffective public policy for cycling safety.
This blog post discrediting mandatory helmet law research refers to already discredited canadian figures.
In some places the laws are only for children and the general canadian public aren’t aware of mandatory helmet laws. The canadian studies are floored because helmet laws aren’t enforced and barely any canadians wear helmets.
Also there was not a decline in cycling in “All” developed “countries”. “Places” that actively encouraged cycling and better cycling infastructure did not experience unhealthy declines in cycling.
Any analysis combining data for adults and children is less powerful than the separate analyses of each reported on the BMJ website – http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1410838/bin/bmj_332_7543_722_a_index.html#fb
Although there may have been a small change in the trend for children, no effect of the law can be seen for adults. Similarly, little or no effect of the law can be seen in any other Australian state, or NZ.
However, accident rates, defined as numbers of hospital admissions divided by numbers of cyclists tell a different story – in many cases they increased. Recent research explains why.
First, A study measured cycling speed of riders who regularly wear helmets – suprise, surprise, they cycled faster wearing helmets than without.
Second, a study measured the amount of room left when motor vehicles overtook cyclists – suprise, surprise, non-helmeted cyclists were given more room, presumably because the drivers considered them more vulnerable.
The Bicycle Victoria website reports a very interesting study showing that
Any analysis combining data for adults and children is less powerful than the separate analyses of each reported on the BMJ website – http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1410838/bin/bmj_332_7543_722_a_index.html#fb
Although there might have been a small change in the trend for children, no effect of the law can be seen for adults. The same research showed there was little or no effect of the law can be seen in any other Australian state, or NZ.
In fact, accident rates, defined as numbers of hospital admissions divided by numbers of cyclists tell a different story. In many cases they increased. Recent research explains why.
First, a study measured cycling speed of riders who regularly wear helmets – surprise, surprise, they cycled faster wearing helmets than without.
Second, a study measured the amount of room left when motor vehicles overtook cyclists – surprise, surprise, non-helmeted cyclists were given more room, presumably because the drivers considered them more vulnerable. The cyclist who measured passing distances was hit twice by motor vehicles, both times when wearing a helmet.
Third, reduced cycling means reduced safety in numbers. Bicycle Victoria’s website reports a very interesting research project that fitted cameras to bike helmets to observe traffic. It confirmed what riders have long suspected—drivers are not paying attention. Of all the incidents recorded by the cameras drivers were at fault 87 per cent of the time, and in 83 per cent of those cases the drivers appeared oblivious of their errors – http://www.bv.com.au/bikes-&-riding/10218/
These factors – risk compensation by cyclists and vehicle drivers and reduced safety in numbers – mean that the average helmeted Australian cyclist has a much higher risk of being killed on the roads than a non-helmeted cyclist in other countries where more people cycle. It seems insane to defend a law that was intended to reduce the risk of head injury, when the data show that the law actually increased head injury rates per cyclist.
Claims that “the popularity of cycling has increased dramatically over the last decade, and can now be described as positively booming, helmet laws notwithstanding” are based on wishful thinking, not real data, such as the census stats that show the percentage of Australians cycling to work is still much lower than before helmet laws – see http://www.cyclehelmets.org/1194.html
Anyone who doesn’t believe that enforced laws deter cycling should compare the popularity of the City Bike schemes in Dublin and Melbourne – http://www.cyclehelmets.org
I would like to live in a country where ‘Safety in Numbers’ makes cycling, where people ride bicycles for transport and this helps keep people fit and healthy, reducing health costs and greenhouse gas emissions. We now know helmet laws increase injury rates because of risk compensation and reduced safety in numbers. Wouldn’t we all be better off without this stupid law?
I have not studied the data in either case.
However the analysis of the revised graph is incorrect.
What it actually shows is the trend in decreasing injuries reduces slightly at the point of heavy helmet promotion prior to the law being introduced, and then resuming its downward trend. I.e. no benefit from the law – as is to be expected given similar results in other jurisdictions.
One thing that is missing in this re-examination is any analysis of the correlation between the injury rate and helmet wearing rate. Such an analysis allows for the normal fluctuations and provides a measure of how closely changes in one quantity (e.g. injuries) is effected by changes to another (helmet wearing). E.g. that hiccup in the rate dropping might be due to the helmet promotion but could easily just be a normal fluctuation so one cannot blame the helmets without further analysis.
Correlation analysis done for other jurisdictions show no drop in head injuries due to the law. The revised graph suggests exactly the same result would occur here.
Conclusion: there may well be an error in the original graph. The revised graph does not prove what it claims and lacks the analysis needed to do so. Indeed the differences between the two graphs do not appear to be statistical significant and in failing to provide proper evidence of his claims Tim Church as undoubtedly strengthened the argument he is trying to negate.
Disclaimer: I am a mathematician but am working only from the two graphs shown.
Tim Churches’s criticism of Voukelatos and Rissel is a valuable contribution to knowledge of effects of compulsory wearing of bicycle helmets upon head injury. But effect on head injury is not suitable for evaluating helmets because for cyclists 95% of it is minor, such as abrasions and contusions to the scalp and cracked skull. The NHMRC has stated that helmets might provide some protection against this, but at the risk of the added weight increasing rotation of the head and fatal and chronically disabling injury to the brain. As fear of these dire results is the focus of official propaganda for compulsory wearing, helmets should be evaluated against brain injury.
For evidence of the efficacy of bicycle helmets, Australian authorities rely upon a meta-analysis of 16 case-control studies, which claims that helmets reduce brain injury. The Australian Transport Safety Bureau (ATSB) published it in Accident in the journal Analysis and Prevention in 2001.
In an article in AA&P in 2003, I showed that the meta-analysis does not provide scientific evidence that helmets reduce brain injury and, indeed, they have potential to aggravate it. I supplemented that with another article in 2005, which makes a similar criticism of the Cochrane review of bicycle helmets, written by Thompson, Rivara and Thompson (TR&T).
In response in 2006, Hagel and Pless from Canada criticised my 2005 article and I rebutted them. Then, T,R&T plus Cummings criticised me and I replied, having the last word in that debate. The references are as follows:
Attewell, R., Glase, K., McFadden, M., 2001. Bicycle helmet efficacy: a meta-analysis. Accid. Anal. Prev. 33, 345-352.
Curnow, W.J., 2003. The efficacy of bicycle helmets against brain injury. Accid. Anal. Prev. 35, 287 292.
Curnow, W.J., 2005. The Cochrane Collaboration and bicycle helmets. Accid. Anal. Prev. 37, 569 573.
Hagel,B.E., Pless, I.B.,2006. A critical examination of arguments against bicycle helmet use and legislation. Accid. Anal. Prev. 38 (2), 277-278.
Curnow, W.J., 2006. Bicycle helmets: lack of efficacy against brain injury. Accid. Anal. Prev. 38, 833-834.
Cummings, P., Rivara, F.P., Thompson, D.C., Thompson, R.S., 2006. Accid. Anal. Prev. 38, 636-643.
Curnow, W.J., 2007. Bicycle helmets and brain injury. Accid. Anal. Prev. 39, 433-436.
ATSB declined to defend its meta-analysis. It thereby relinquished any claim to scientific validity, yet it continues to advise transport ministers that bicycle helmets reduce the risk of death or brain injury for cyclists, and that use of them should increase. When challenged, ATSB disclaimed all responsibility for the advice, but Victoria, for one, and now, apparently, NSW rely on the meta-analysis for the continuing claim that helmets save lives.
By contrast with the honesty of Voukelatos and Rissel, who admitted to error and accepted correction, authorities stubbornly maintain their position against scientific evidence.
Bill
No Dave I got the point I just think that we would be better off spending time focusing on increasing cycling safety rather than removing a proven safety measure.
But can I just get some clarification? The logic from the anti camp seems to be that more people will use bikes for short slow rides if they don’t have to wear a helmet and somehow this minimal level of exertion will have an health benefit. I’m buggered if I can see how but that’s what you’re arguing? Additionally, the removal of a compulsion will not also result in many more head injuries to people who now choose not to wear helmets but previously did?
Ridestowork you should delve more deeply into the BV website and find the bit where they say helmets are a good thing that significantly reduce head injury and ponder on the effect allowing people ride fast or in traffic without helmets.
Disclosure – I didn’t wear a helmet when I rode to the IGA for milk this morning and I would have had more exercise had I walked.
it’s always good to examine the methodology of studies like this. Tim Churches makes some very interesting observations on some of the assertions Chris Rissel makes regarding the arm injuries. I was a bit doubtful of the validity of those claims right from the start. But let’s not get away from the main thrust of Chris Rissel’s paper. His point that we’ve not had a net benefit from the compulsion to wear helmets is no less valid. This law was introduced without any research or consultation at all. There has been precious little since then. There has been no convincingly demonstrated benefit to the community. You can put up all the anecdotes you like about helmets supposedly saving someone’s life. The data do not support the claim that forcing all cyclists to wear helmets has a net benefit to the community. And a very merry Christmas to all you safety-zealots who have completely failed to comprehend the very plain English I have written here.
@SBH happy to clarify
I’m not arguing that removal of helmet laws will have a positive heath effect because more people will ride to the shops and therefore get fitter (but I do think that will happen – every substitution of sedentary transport with active transport has a positive health effect and half of all car journeys in Oz are under 5km).
What I’m arguing is that removing helmet laws won’t have any negative impact on cycling safety, and will actually make cycling more safer. To explain….
Helmet laws, for a variety of reasons, act as a disincentive to cycling. Perceived danger, inconvenience, comfort, helmet hair, what ever. There is plenty of evidence to support the claim that helmet laws are a disincentive cycling (primarily for utility cycling), and very little to dispute this.
More people cycling equals safer cycling because there will be fewer drivers, and remaining drivers adjust their behaviour to the increasing number of cyclists. Again, there is plenty of evidence to support the claim of the safety-in-numbers effect with numerous studies showing a 1/3 – 1/2 inverse relationship – doubling the number of cyclists improves individual safety 30%-50%.
I agree that there are other more important safety issues for cycling than helmets. Lower car speeds, separated infrastructure, more respect between all road users would do far more than helmet laws. Approx 80% of cycling fatalities involve collision with a motor vehicle and a bike helmet won’t do much in a 60kph+ collision.
Having the freedom, as opposed to coercion, to wear a helmet means people can choose to do so when they perceive it needed. I would argue that most cyclists are acutely aware of the likely outcome of a collision with a motor vehicle and act accordingly (just like the rest of the world does – and you did yesterday to the IGA).
No anecdotes Michael Fanning, a peer reviewed study of 44,000 hospitalisations perhaps but ,well, you know, moses and the prophets……
Dave you’ve got some studies that show how helmets stop people riding? Please spread the word
Mandatory helmet laws are hardly a “road to serfdom,” but from reading all the above it seems helmets are probably good, mandatory helmets may be good, but we’re not sure. In situations like this, another option is to let riders choose, but make it mandatory for cycling shops to display information on helmets and to draw customers’ attention to it.
Chris Rissel maintains (comment #1) that head injuries started dropping in the 1980s, before the promotion of helmets. That’s probably true, I’d be surprised if that wasn’t the case given all the other safety reforms including RBTs, speed radar, and the visibility revolution in reflective clothing and electric lights. It’s hard to imagine now what a bloodbath the roads were in the 1970s and how many of the people you knew would not make it home.
Thanks Tim for pointing out the silly mistakes made in the data I calculated. My original intention in the method I employed was to try to suggest an alternative way of looking at cycling data that avoids the denominator problem. I’d like to point out that using hospital records to try to evaluate the effectiveness of mandatory helmet legislation is not ideal. ICD codes were not developed for such purposes. However, in the absence of other routinely collected data is this the only way we have of assessing the impact of this legislation in the community? As we can’t go back in time to introduce a better surveillance system, perhaps this issue will never have a definitive answer.
I suggest that the debate on the effectiveness of mandatory cycling legislation is a side issue in light of other strategies, such as teaching more kids about safe cycling, which would in time produce more aware cyclists and drivers
Alex Voukelatos
Sadly FC there is one part of the country where you can still experience a 1970’s road trauma experience. The NT where rates of death and injury are still frighteningly high.
It’s amazing that there are still people that believe that helmet laws have any effect on cycling levels, despite mountains of evidence to the contrary. Whether one believes in helmet laws or not, the fact is that they have never been shown to have any effect on cycling levels one way or the other.
It’s also amazing that after all this time we still see attempts to correlate bicycle safety with low helmet usage. Surely no one believes that the reason for high levels of cycling in the Netherlands is caused by low helmet usage. Correlation does not equal causation.
And of course we still see the smarmy references to “styrofoam hats” a sure sign the the writer knows not of what they speak.
Most of the comments here are missing the basic premise of the argument, which is that it is up to the proposers of a law to demonstrate that it is socially beneficial. No-one, despite all the hyperbole, anecdote and sheer invented statistics, has been able to do so, therefore cycle helmet laws must be deemed to be an expensive failure. Just imagine all the muggings and murders the police would have been able to prevent if they weren’t hunting down those ruthless, society wrecking criminals, helmetless cyclists. The whole point of cycle helmet laws was to reduce the head injury rate of cyclists, but there is no reliable evidence to support that. It doesn’t matter that some people who question the validity of imposing unproven laws may have got some data wrong, it is up to the helmet law true believers to prove their case, which, despite more than twenty years of helmet laws, they still can’t do.
Typical of the helmet propaganda is John Kerr’s assertion “In one Victorian rural city I lived in, at least two teenaged kids at the school had their lives saved (without doubt) by wearing helmets when they were dragged under trucks.” In the first place, anyone who feels the need to use the phrase “without doubt” is obviously not sure of their facts, and anyone who believes that a cycle helmet could save your life if you were dragged under a truck is mistaken enough to be described as delusional. Cycle helmets are designed to mitigate the effects of a single vehicle accident ie when the cyclist falls off. They are not designed for collisions with motor vehicles, and no-one in their right mind contends that they are – certainly the manufacturers and testers don’t.