Medics focusing on helmets is a distraction to injury prevention and population health

COMMENT & ANALYSIS: St Vincent’s University Hospital in Dublin are treating us to more of the same weak research on the relationship between helmet wearing and head injury… and then dressing it up as the solution to injury reduction.

The Irish Examiner quoted Dr John Cronin, a consultant at St Vincent’s, as stating: “We found that those who did not have a helmet had a significantly higher incidence of head injury.”

Dr Cronin was challenged on Twitter by a few people, but the best question came from @clicky_here, who said: “Are raw data from this research available? Correlation is one thing, but drawing conclusions is questionable – not least since we know that cycle helmets are not designed or tested to withstand road traffic collisions involving motor vehicles. What were the circumstances in each case?”

Dr Cronin replied: “Yes this is just an association with retrospective data and that was highlighted at the presentation. Cannot prove causation. In depth details on all the circumstances of the accidents not available. Unfortunately the tweets don’t draw out all the new nuances.”

Following up, @clicky_here said: “Thank you, John, for your considered reply. In light of that would you have any comment about this article in the Examiner – it doesn’t seem to capture the nuance you’ve mentioned here.”

No reply yet from Dr Cronin. What seem to be the print version of the article has an even wider claim in its headline: “Helmets cut cyclist head injuries by half” — which is clearly unsupported nonsense.

The Irish Times also covered it. “Twelve of the cyclists died, all of whom had head injuries, according to Dr John Cronin, emergency medicine consultant at St Vincent’s University Hospital in Dublin,” the Irish Times reported. Adding: “Wearing a helmet was associated with a significantly reduced rate of head injury, he said.”

The reporting of “Twelve of the cyclists died, all of whom had head injuries” by The Irish Times is even stranger when confronted by the Examiner’s line that: “There were 12 fatalities. Of those admitted to intensive care, five were wearing a helmet.”

This type of reporting in any case is worrying — most fatal collisions in recent years (looking at all collisions, not just those who made it to hospital and were counted in the above mentioned research) seem to be at speeds where helmets would not protect people. Out of context

This isn’t just the word of cycling advocates and a cycling-focused journalist. As many readers will know, the website’s favorite article on helmets was published in the British Medical Journal and penned by Ben Goldacre, Wellcome, research fellow in epidemiology and author of Bad Science, and David Spiegelhalter, Winton professor for the public understanding of risk.

Their article is worth reading but the key bit in relation to what Dr Cronin has made public is:

“These [pro-helmet] 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.”

The Irish researchers are also dealing with mixing all types of cycling, including off-road cycling and road racing with commuting on an upright bicycle — this is like mixing motorsports with driving to the shop.

The large “unspecified” interactions is also a worry — reported hints at claiming most or all of these are cyclists falling off their bicycles without detailed further research makes it worse.

Meanwhile, 1,000km away from Ireland, the Dutch have build cycling into their daily routine. Their roads and streets used to looks like ours. The health benefits are clear, all age groups do it because it’s safe and attractive and 0-1% helmet wearing rate. We can do the same by following and related measures.

In fairness to Dr Cronin he is quoted by The Irish Times as saying: “Examining the injury characteristics suggests preventative strategies such as improved cycling infrastructure may be required.” But as our headline states: Medics focusing on helmets is a distraction to injury prevention and population health. The cycling infrastructure mention was all but lost among the coverage and the debate online.

There’s always somebody who pipes up and says something like “but sure people can go do something safer like go for a run or join a gym” — however, the health experts dealing with inactivity are clear: Building activity into people’s daily routine is far better, wider ranging, and more sustainable (in the longer-lasting sense). There’s also feedback loops too — reduction in car space and use also has the benefit of imp

Then there’s another one saying it’ll take too long to change our built environment — there’s no time like the present to start and it would happen faster if more people got behind it (for example, asking politicians to sign up to or asking their employers to sign up to CyclingWorks Dublin or Cork) rather than continuing with distractions.


  1. Thanks for that analysis Cian. On Twitter I asked Dr. Cronin to disaggregate the serious injuries obtained from everyday cycling as opposed to participating in sports cycling (racing, out on club runs, sportives, MTB, etc.).
    We need clarity on what proportion are a result of RTCs or impacts with road furniture, potholes, etc. happening to ordinary folks pootling along to work, school, college, shopping, etc.
    And how many result from the rider having a medical condition causing a fall off the bike?

  2. * In Boxing head-guards have been scrapped because the most serious issue is the rotating of the brain inside the skull and boxing head gear (and cycling helmets also) do nothing to protect us from that aspect of a head injury.

    * Anecdotally, I believe that the increasing emphasis (driven by jeep drivers in the media) on pressurizing cyclists instead of drivers has caused a surge in almost psychopathic careless driving towards cyclists.

    *Media continue to refer to cars hitting cyclists as “Collisions” and peiopl;e who are klilled as having “passed away”. I am not religious and people are dying. Being killed , and will not be passing to anywhere at all. Just dying dead and gone forever.

    * We are expected to illuminate with high-viz now in the daytime also? I have been lit up like a Christmas tree and still been run into by car driverrs on four occasions (BTW I have not made claims either- another insult drivers and nmedia throw at cyclists- but I definitely should have)

    *We have to keep the emphasis on drivers NOT HITTING CYCLISTS, not allow this sinister anti-cyclist trend to go unchecked.

    Great article, as usual. Well done,Thanks..

  3. I’d also be interested to know about how they dealt with response bias, if many of the patients reported helmet use themselves, rather than it being observed. People without head injuries may claim to have been wearing them to avoid guaranteed disapproval from medical staff, since they can assume they’ll be believed.

    Also, the association is claimed for “head injuries”, and by “significant” it seems to be implied that it’s statistically significant. If so, does the significance also hold up for the much small subset of head injuries that are serious (usually much smaller anyway).

  4. As mentioned previously, I’d like to see the data related just to people commuting on bikes on public roads, and separated from people on bikes doing road-racing, CX, or mountain biking. I’d further like to see the data separated between those people who are involved in collisions with cars and have that compared to pedestrians who are hit by cars. I will bet right now, that there is no meaningful difference between people on bikes hit by cars and people walking hit by cars.


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