Is cycle helmet promotion warranted? DK v NL data

[Nearholmer]

Steady Rider

I don’t want to come over as wishing to start an argument, but the problem with each of those snippets is that it begs far more questions than it answers.

The first one is particularly intriguing, because what I think it might be saying is that in areas that held cycling promotion campaigns that included promoting helmets, cycling went up, while in areas that held a helmet promotion campaign without promoting cycling, it went down. It’s really not clear at all.

TBH, some of the papers on the topic that I’ve seen simply wouldn’t survive peer review if put forward for a formal engineering journal, and wouldn’t obtain more than a bare pass if submitted as masters dissertations. Others are brilliant pieces of work, well executed and described, but focusing on tiny, very narrow sub-questions, so don’t really illuminate the big issues ….. an analogy might be presenting a paper on material loss from tungsten lightbulb filaments during use, and then trying to base a national street lighting policy on only that.

It’s an are crying out for really hard-headed(!) structuring of the research, rather than leaving individual researchers to pop up with whatever catches their interest or looks likely to garner them a qualification.

[Jdsk]

It’s an are crying out for really hard-headed(!) structuring of the research, rather than leaving individual researchers to pop up with whatever catches their interest or looks likely to garner them a qualification.

There are published systematic reviews in this field which state clearly the questions that they are trying to answer and the methods that they have used. And systematic reviews following typical guidelines should now include assessments of their own limitations.

In previous discussions in this forum they have met some responses that include dismissal because they breach dogma or on ad hominem grounds, and with whataboutery based on analogies.

But it's really important for anyone interested in this field to be familiar with all of the published systematic reviews and understand them because they affect those responsible for public health policy. As well as being the best currently available method for determining what we know and what we don't know.

Jonathan

[Steady rider]

- what affect does promoting helmet wear have on the take-up of cycling? (Possibly needing a “by sector” analysis, because it may affect sport, casual leisure, and utility cycling differently)

The paper compares two major cycling countries, Denmark that has promoted helmets and the Netherlands that has not taken the same approach. The changes in cycling levels, minus 15% v plus 19%, strongly indicates helmet promotion does in fact discourage cycling.

One major problem could be in not having sufficient discussion on the various issues and setting procedures that narrow the focus to questions not covering overall safety.

[Jdsk]

The paper compares two major cycling countries, Denmark that has promoted helmets and the Netherlands that has not taken the same approach. The changes in cycling levels, minus 15% v plus 19%, strongly indicates helmet promotion does in fact discourage cycling.

The paper does not to explain why those two countries rather than any other countries were studied. It doesn't explain why those particular time periods were selected.

These are basic requirements of any study based on time series.

As with any study based on association there should be an analysis of possible confounders. The author's wording in the paper is:

"Changes in cycling activity could also be linked to other changes apart from helmet promotion, however, helmet promotion could also be a prime reason."

but in this thread you have changed that to:

"The changes in cycling levels, minus 15% v plus 19%, strongly indicates helmet promotion does in fact discourage cycling."

Jonathan

[Steady rider]

"Changes in cycling activity could also be linked to other changes apart from helmet promotion, however, helmet promotion could also be a prime reason."

In the case of Denmark, they should fully investigate any reasons for their reduction in cycling levels. The two countries have high cycling levels, both promote cycling, both have similar road safety levels. Denmark chose to promote helmets, so comparing changes in cycling levels fitted the discussion.

"The changes in cycling levels, minus 15% v plus 19%, strongly indicates helmet promotion does in fact discourage cycling."

Most of the reduction in cycling appears to be for children/teenagers, that have been the target for increased helmet wearing, so it suggests helmet promotion does discourage cycling.

[Jdsk]

"Changes in cycling activity could also be linked to other changes apart from helmet promotion, however, helmet promotion could also be a prime reason."

In the case of Denmark, they should fully investigate any reasons for their reduction in cycling levels. The two countries have high cycling levels, both promote cycling, both have similar road safety levels. Denmark chose to promote helmets, so comparing changes in cycling levels fitted the discussion.

"The changes in cycling levels, minus 15% v plus 19%, strongly indicates helmet promotion does in fact discourage cycling."

Most of the reduction in cycling appears to be for children/teenagers, that have been the target for increased helmet wearing, so it suggests helmet promotion does discourage cycling.

Are you saying that there are no possible confounders in the reported association? That's not what the author of the paper said, as quoted above... "other changes apart from helmet promotion"... and those cautious uses of "could". You've used completely different levels of certainty in this thread, eg "strongly indicates".

Jonathan

[Steady rider]

The paper provides the opportunity for anyone from Denmark to explain why any other factors could have discouraged cycling. It shows cycling levels in some main cities increasing and I gather they have invested in cycling infrastructure. The info from Cycling Embassy details a 17% reduction at a national level. The accident data for the younger age groups suggest their cycling reduced. Denmark should publish the average hours or km cycled by age group to cover the period of the past 20 years to compare with helmet promotion.
My view is helmet promotion has discouraged cycling and extra details may be helpful.

[Mike Sales]

Changes in cycle use in Australia
Summary

The enactment of helmet laws in Australia in the early 1990s had a major impact on cycle use. Whereas cycle use prior to the laws had been generally increasing, as soon as laws were passed and enforced cycle use fell sharply.

This page looks at the evidence that is available, nationally and state by state, on trends in cycle use since the passing of helmet laws.

There were early signs that helmet compulsion might cause some people to give up cycling, such as when many students at schools in Victoria chose to give up cycling when they were required to wear helmets pre-law (AHoR, 1985b). It would therefore have been sensible for governments to ensure that the effect of compulsory wearing on numbers of cyclists was monitored accurately. This was not done, but some measurements of numbers were made, most being incidental to surveys of helmet wearing.

https://www.cyclehelmets.org/1194.html

[Steady rider]

According to household travel surveys, the numbers of person trips per day in Adelaide were 3.4 million in 1986 and also 3.4 million in 1999, the numbers as car driver being 1.8 and 2.0 million, and the numbers by bicycle being 0.089 and 0.040 million.
The Census data for South Australia shows bicycle, 2.27% v 1.27%, 1986 to 1996, a reduction of 44%, The 0.04 v 0.089 million relates to a 55% reduction, 1986 to 1999.

[Nearholmer]

Compulsion.

That I can definitely imagine putting people off.

But, compulsion and advocacy done well, are very different things.

[Steady rider]

Just to clarify some of the method issues.
The general risk assessment provides all the references needed to check and provides an indication of the risk of hospital admission for head injury.
Comparing helmeted to non-helmeted, mainly relates to the 40 studies included by Olivier and Creighton. Zeegers stated

‘It must be concluded that any case-control study in which the control is formed by hospitalized bicyclists is unreliable and likely to overestimate the effectiveness of the bicycle helmet. As a direct consequence, also meta-analyses based on these case-control studies overestimate the effectiveness of the bicycle helmet. Claims on the effectiveness of the bicycle helmet can no longer be supported by these kind of studies. This might explain the discrepancy between case-control studies and other studies, such as time-analysis. It is recommended to use other methods to estimate the risk ratio for the bicycle helmet, along the lines described in this article.’

-
Zeegers could only find 3 of the 40 studies where a risk evaluation could be made and these were mentioned in the paper.
In considering if helmet promotion is warranted, any issues reported of concern have to be mentioned, so extra impacts and increased risk are referred to. A number of concerns relating to helmet promotion and helmet laws are mentioned. Changes in cycling levels for Denmark that has promoted helmets and the Netherlands are compared. A cost effectiveness calculation of helmet promotion based on DK and NL is provided, showing a major loss for DK.
Concerns about the Highway Code and it being used to unfairly reduce accident compensation for cyclists, who have not been wearing helmets and suffered head injuries, due to motorists being at fault are detailed.
The outcome from countries with helmet legislation and indication of cycling levels, such as New Zealand and in NSW, are provided. Both again raising concerns, with increased risk levels.
With limitations on space, 12 pages, and focusing on the main issues, the method was a practical approach to addressing the concerns.
Other methods may be no more effective and potentially more confusing to the reader.

[Steady rider]

y Nearholmer » 9 Jul 2022, 3:59pm wrote

Compulsion.

That I can definitely imagine putting people off.

But, compulsion and advocacy done well, are very different things.

Denmark could see the problems with legislation but the results show even helmet promotion can also have serious negative consequences.

[Jdsk]

Just to clarify some of the method issues.
The general risk assessment provides all the references needed to check and provides an indication of the risk of hospital admission for head injury.
Comparing helmeted to non-helmeted, mainly relates to the 40 studies included by Olivier and Creighton. Zeegers stated

‘It must be concluded that any case-control study in which the control is formed by hospitalized bicyclists is unreliable and likely to overestimate the effectiveness of the bicycle helmet. As a direct consequence, also meta-analyses based on these case-control studies overestimate the effectiveness of the bicycle helmet. Claims on the effectiveness of the bicycle helmet can no longer be supported by these kind of studies. This might explain the discrepancy between case-control studies and other studies, such as time-analysis. It is recommended to use other methods to estimate the risk ratio for the bicycle helmet, along the lines described in this article.’

-
Zeegers could only find 3 of the 40 studies where a risk evaluation could be made and these were mentioned in the paper.
In considering if helmet promotion is warranted, any issues reported of concern have to be mentioned, so extra impacts and increased risk are referred to. A number of concerns relating to helmet promotion and helmet laws are mentioned. Changes in cycling levels for Denmark that has promoted helmets and the Netherlands are compared. A cost effectiveness calculation of helmet promotion based on DK and NL is provided, showing a major loss for DK.
Concerns about the Highway Code and it being used to unfairly reduce accident compensation for cyclists, who have not been wearing helmets and suffered head injuries, due to motorists being at fault are detailed.
The outcome from countries with helmet legislation and indication of cycling levels, such as New Zealand and in NSW, are provided. Both again raising concerns, with increased risk levels.
With limitations on space, 12 pages, and focusing on the main issues, the method was a practical approach to addressing the concerns.
Other methods may have no more effective and potentially more confusing to the reader.

Is this about:

The Universities Transport Study Group 54th Annual Conference was held 4-6 July at Edinburgh Napier University and included a paper by Colin Clarke, ‘Is cycle helmet promotion warranted?’.
...
https://www.researchgate.net/publicatio ... _warranted

You've already told us that the author made subjective choices about which studies to include and which not and that the criteria for that decision aren't available.

Once that has been established the paper has no value as a fair summary of the available evidence.

If I submitted a review with a Methods section like that I'd expect it to be rejected. If I was asked to comment on it I'd recommend rewriting it with a Methods section that described what was done. If was an editor I wouldn't publish it.

Of course campaigning journalism, unlike scientific publication, isn't subject to these controls.

Jonathan

[Jdsk]

https://www.cyclehelmets.org/1194.html

No author. No affiliation. No date. No methods.

As above: may be OK for campaigning journalism but no use as a scientific contribution.

Jonathan

[Stevek76]

The paper provides the opportunity for anyone from Denmark to explain why any other factors could have discouraged cycling. It shows cycling levels in some main cities increasing and I gather they have invested in cycling infrastructure. .

I think there is another clear factor here. Denmark has been doing infrastructure but simply not as fast nor as well as the Dutch. Regardless of whatever Colville-Andersen likes to claim via his blatantly rigged Copenhagenize index, Danish provision isn't a patch on the Dutch and this is reflected in the demographics seen cycling as with fewer very young, very old etc Danes getting about on bikes.

Both countries have seen, much as any country, a continuing shift to cars in more rural areas due to ever cheaper real terms costs of motoring, increasing disposable incomes, lack of safe cycle infra and inevitably poorer PT provision. The Dutch however have continued to really squeeze motoring in urban areas and have better junction designs where drivers and cyclists do need to interact, hence the national mode share has remained stable with urban increases offsetting the rural drop. Danish urban shares have been rather more stable at best with failures to really capitalise on earlier gains.

I'd be surprised if stupid helmet campaigns haven't harmed things, I recall cycling uk has a reasonable summary of the evidence on this point and as they point out even though it's hard to quantify any such effect, the health benefits of cycling are so vast and the chance of incurring a serious head injury so low that you only need to put off a tiny amount of cycling to make it entirely impossible to have a net public health gain.