Once a week.
Subscribe to our weekly newsletter.
The Bike Helmet Paradox
Recently a good friend told me over a pint in our local pub that he hadn't been able to sleep a wink for two nights. He'd been left traumatised by the sound of a skull cracking and the sight of brains spread over concrete. No, he hadn't just returned from fighting in Afghanistan, he'd witnessed one of the many cycling deaths that occur on the roads every year. We all have stories to tell about the wearing or not wearing of helmets and this is what makes the wearing of helmets such an emotive issue, which can blind us to the facts on both sides of the debate. I was subsequently intrigued to read a viral post on a friend's Facebook wall titled: "Why It Makes Sense To Bike Without A Helmet". The post currently has over 91,000 likes on Facebook, which I thought warranted it some investigation.
The author begins, like any good debater by outlining the very strong case for helmets:
"Let’s first get one thing out of the way: if you get into a serious accident, wearing a helmet will probably save your life. According to a 1989 study in the New England Journal of Medicine, riders with helmets had an 85% reduction in their risk of head injury and an 88% reduction in their risk of brain injury. That’s an overwhelming number that’s backed up study after study. Nearly every study of hospital admission rates, helmeted cyclists are far less likely to receive serious head and brain injuries. These studies confirm what we feel when we’re out for a spin on our bikes: We are exposed. Vulnerable. Needing of some level of protection."
After this good start, the author decides to take a "broader look at the statistics" by zoning in on one study of head injuries in San Diego in 1978. The author points out that only six percent of head injuries were amongst cyclists compared to 53% amongst drivers - seemingly oblivious to the fact that there would have been far more daily drivers than cyclists in San Diego in 1978, making the statistic more than a little misrepresentative. The author provides the pie chart on the left, which is considerably less impressive when placed alongside the pie chart on the right showing the rate at which American commuters actually cycle (the data on the right is from 2005 but the proportion of commuters cycling in the US has remained below 1% since the 70's).
Next the author points out that in the San Diego study and in another French study that was also not weighted for population: "more people were hospitalized after walking down the street than riding on a bicycle", a statistic that can likely be explained by the fact that while more or less everyone walks to some extent, relatively few people regularly cycle and old people tend to hurt themselves falling over a lot.
This is where things begin to get messy. The author cites a 1996 study which looks at injuries per hour travelled and suggests that motor vehicle occupants are actually slightly more likely to suffer head injury than cyclists. On the face of it, this is a shocking statistic, but considering the speed that cars travel, it is should perhaps not actually be surprising that cars may even be more dangerous to their occupants (and to others) than push bikes - and the suggestion that car drivers should wear helmets is certainly a compelling thought to say the least. Whether or not this is relevant information to whether cyclists should be singled out for wearing helmets is certainly an interesting topic for debate. In this respect, it is difficult to argue with the author who writes:
"In other words, if the reason we are supposed to wear helmets while biking is to prevent serious head injury on the off-chance we get into an accident, then why is it socially acceptable for pedestrians and drivers to go about bare-headed? Why has cycling been singled out as an activity in need of head protection?"
Things become yet more interesting when we scratch further beneath the surface. The author of the blog post writes:
"There's an important caveat to the results of that 1989 New England medical study: Bike helmets may reduce the risk of head and brain injury by 85-88%—but only for those who get into accidents.
If we take a closer look at the article we see that both the experiment and the control groups studied are those who have already been hospitalized for bike injuries. If one were to examine the medical and epidemiological literature on bike helmet effectiveness, you'll find the exact same condition over and over: Studies show that helmeted cyclists who are hospitalized are far less likely to have serious head trauma than bare-headed cyclists that have been hospitalized.
But wouldn't this be true, regardless of the activity? Logically, helmeted drivers should also receive significantly fewer head injuries than bare-headed drivers. Similarly, helmeted pedestrians should be less likely to receive serious head trauma than bare-headed ones. But such studies don't exist because there aren't enough helmeted drivers or pedestrians to make a comparison. In other words, one of the reasons we think helmeted cyclists are safer than unhelmeted ones may be due to availability of information more than actual levels of head safety.
Maybe that explains why there's no comparable fear of driving or walking without a helmet."
So the evidence remains clear that cyclists who wear helmets who have accidents are less likely to suffer brain injuries than cyclists that don't wear helmets that have accidents - which in my mind is evidence enough to more than justify wearing a helmet. The obvious next question is - are cyclists who wear helmets somehow more likely to get into accidents than cyclists who do not wear helmets - this is a complicated and fascinating debate, which we'll come back to later in this post. But this is not the case the author makes. The author takes the cognitive leap to suggesting that helmets in and of themselves might actually be harmful.
The author cites a New York Times article which reports an increase in bicycle head injuries during a time when helmet use became widespread which coincided with an overall decrease in cycling. There is an obvious correlation ≠ causation issue here which we could talk about all day from a great many different angles, so we'll begin by looking at the author's arguments one by one.
First, the author argues that "wearing a helmet changes how drivers perceive the cyclist" citing a study that suggests drivers pass closer to a cyclist wearing a helmet. The naturalistic study involving only one participant (who was also the experimenter) is interesting, but obviously potentially vulnerable to the same kind of conscious or unconscious bias that might lead a driver to drive closer to a cyclist. On its own it is not compelling evidence for the argument that one should not wear a helmet.
Next the author argues that "the design of the helmets themselves may increase the chance of some types of injuries when incidents do occur" linking to a meta-analysis but conveniently failing to mention what the meta-analysis actually found overall:
"In conclusion, the evidence is clear that bicycle helmets prevent serious injury and even death"
The author also failed to mention that the meta-analysis concluded that the supposed increase in (neck) injuries was found in old data and may not be applicable to the lighter helmets now in use. So that argument is also null and void - and a textbook example of cherry-picked data amongst a sea of data showing the precise opposite.
The author ends their case for the argument that helmets may be harmful with a crucial point which is worth thinking long and hard about if you are a cyclist:
"Finally, wearing a helmet may create a false sense of security and induce risk-taking that cyclists without head protection might not make. Those wearing helmets may take risks that they wouldn't otherwise take without head protection."
Due to the ethical problems that prevent researchers asking cyclists to ride with or without a helmet, this is a difficult hypothesis to test - but it certainly seems likely that wearing a helmet might lead cyclists to overcompensate by taking greater risks. It is worth reminding yourself that a helmet only provides limited protection even though it might lead some people to behave like they are invincible. If helmets really do make cyclists take greater risks then making their use obligatory presents an interesting public health conundrum. Is it possible that helmets could make people safer if they have an accident whilst simultaneously making them behave even more dangerously? It is next to impossible for us to know for sure if this is occurring due to the immense amount of additional uncontrollable variables in the equation.
The author of the blog post makes a number of good points but seems to have overstated the case. These arguments highlight the fact that when it comes to human behaviour, epidemiological data gets incredibly messy and it is can be all too easy to intentionally or not, make whatever argument we want based on what data we look for. We've not even touched on the possibility that the type of casual cyclist who chooses not to wear a helmet may already behave very differently to the type of cyclist who does choose to wear a helmet. As Ben Goldacre explained in an editorial on bike helmets in the British Medical Journal, we are dealing with "confounding variables that are generally unmeasured and perhaps even unmeasurable."
What we are left with is a paradox. On an individual level it is clear that helmets can and do save cyclists from serious head injury and death provided that cyclists and the drivers around them don't overcompensate by taking greater risks. On a societal level, it seems that laws enforcing helmet use have done nothing to make cyclists safer and have driven a great many casual cyclists off the road - which as the author of the post rightly points out, indirectly increases the danger to cyclists in the long run, as cyclists are protected by strength in numbers. Furthermore, in places where helmet requirements have driven cyclists off the road it has been argued that the negative effects on public health outweigh any possible benefits in prevented injuries. In Australia, when a helmet law was introduced at a time when the popularity of cycling was on the rise, a 44% decrease in children cycling was observed, which was five times the size of the increase in children wearing helmets. According to a paper published in the BMJ, it would take "at least 8000 years of average cycling to produce one clinically severe head injury and 22,000 years for one death". It has also been estimated that the health benefits of cycling outweigh the life-years lost by a factor of twenty to one.
The whole argument reminded me of an anecdote regarding the introduction of helmets for soldiers in WW1 and the supposed consequent increase in recorded head injuries. As the story goes, generals nearly recalled the helmets before it was realised that the rise in head injuries could be explained by injuries that before the introduction of helmets would have been recorded as deaths. I've been unable to track down a bona fide citation for this anecdote amongst the many repetitions of it online (but I've not found any attempts to disconfirm it either). In any case, this has certainly not been true for bike helmets - where deaths still make up a tiny fraction of outcomes from bike accidents, but it is an interesting demonstration of how statistics can mislead - something that seems to be going on left, right and centre in the bike helmet debate.
After looking at the evidence, I'm happy to conclude that I'll choose to wear a helmet, but I'll not be beating the drum that cyclists should be forced to wear helmets - as the health benefits of cycling with or without a helmet are so great, that the risks of riding with or without a helmet pale in comparison. The evidence paradoxically seems to show that while wearing helmets does make cyclists safer, helmet laws don't make cyclists safer and actually harm public health in the long run.
Attewell R.G., Glase K. & McFadden M. Bicycle helmet efficacy: a meta-analysis., Accident; analysis and prevention, PMID: 11235796
Goldacre B. & Spiegelhalter D. (2013). Bicycle helmets and the law., BMJ (Clinical research ed.), PMID: 23760970
Robinson D. (1996). Head injuries and bicycle helmet laws, Accident Analysis & Prevention, 28 (4) 463-475. (PDF)
Walker I. (2006). Drivers overtaking bicyclists: objective data on the effects of riding position, helmet use, vehicle type and apparent gender., Accident; analysis and prevention, PMID: 17064655
Wardlaw M.J. Three lessons for a better cycling future., BMJ (Clinical research ed.), PMID: 11124188
Northwell Health is using insights from website traffic to forecast COVID-19 hospitalizations two weeks in the future.
- The machine-learning algorithm works by analyzing the online behavior of visitors to the Northwell Health website and comparing that data to future COVID-19 hospitalizations.
- The tool, which uses anonymized data, has so far predicted hospitalizations with an accuracy rate of 80 percent.
- Machine-learning tools are helping health-care professionals worldwide better constrain and treat COVID-19.
The value of forecasting<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTA0Njk2OC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyMzM2NDQzOH0.rid9regiDaKczCCKBsu7wrHkNQ64Vz_XcOEZIzAhzgM/img.jpg?width=980" id="2bb93" class="rm-shortcode" data-rm-shortcode-id="31345afbdf2bd408fd3e9f31520c445a" data-rm-shortcode-name="rebelmouse-image" data-width="1546" data-height="1056" />
Northwell emergency departments use the dashboard to monitor in real time.
Credit: Northwell Health<p>One unique benefit of forecasting COVID-19 hospitalizations is that it allows health systems to better prepare, manage and allocate resources. For example, if the tool forecasted a surge in COVID-19 hospitalizations in two weeks, Northwell Health could begin:</p><ul><li>Making space for an influx of patients</li><li>Moving personal protective equipment to where it's most needed</li><li>Strategically allocating staff during the predicted surge</li><li>Increasing the number of tests offered to asymptomatic patients</li></ul><p>The health-care field is increasingly using machine learning. It's already helping doctors develop <a href="https://care.diabetesjournals.org/content/early/2020/06/09/dc19-1870" target="_blank">personalized care plans for diabetes patients</a>, improving cancer screening techniques, and enabling mental health professionals to better predict which patients are at <a href="https://healthitanalytics.com/news/ehr-data-fuels-accurate-predictive-analytics-for-suicide-risk" target="_blank" rel="noopener noreferrer">elevated risk of suicide</a>, to name a few applications.</p><p>Health systems around the world have already begun exploring how <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7315944/" target="_blank" rel="noopener noreferrer">machine learning can help battle the pandemic</a>, including better COVID-19 screening, diagnosis, contact tracing, and drug and vaccine development.</p><p>Cruzen said these kinds of tools represent a shift in how health systems can tackle a wide variety of problems.</p><p>"Health care has always used the past to predict the future, but not in this mathematical way," Cruzen said. "I think [Northwell Health's new predictive tool] really is a great first example of how we should be attacking a lot of things as we go forward."</p>
Making machine-learning tools openly accessible<p>Northwell Health has made its predictive tool <a href="https://github.com/northwell-health/covid-web-data-predictor" target="_blank">available for free</a> to any health system that wishes to utilize it.</p><p>"COVID is everybody's problem, and I think developing tools that can be used to help others is sort of why people go into health care," Dr. Cruzen said. "It was really consistent with our mission."</p><p>Open collaboration is something the world's governments and health systems should be striving for during the pandemic, said Michael Dowling, Northwell Health's president and CEO.</p><p>"Whenever you develop anything and somebody else gets it, they improve it and they continue to make it better," Dowling said. "As a country, we lack data. I believe very, very strongly that we should have been and should be now working with other countries, including China, including the European Union, including England and others to figure out how to develop a health surveillance system so you can anticipate way in advance when these things are going to occur."</p><p>In all, Northwell Health has treated more than 112,000 COVID patients. During the pandemic, Dowling said he's seen an outpouring of goodwill, collaboration, and sacrifice from the community and the tens of thousands of staff who work across Northwell.</p><p>"COVID has changed our perspective on everything—and not just those of us in health care, because it has disrupted everybody's life," Dowling said. "It has demonstrated the value of community, how we help one another."</p>
"You dream about these kinds of moments when you're a kid," said lead paleontologist David Schmidt.
- The triceratops skull was first discovered in 2019, but was excavated over the summer of 2020.
- It was discovered in the South Dakota Badlands, an area where the Triceratops roamed some 66 million years ago.
- Studying dinosaurs helps scientists better understand the evolution of all life on Earth.
Credit: David Schmidt / Westminster College<p style="margin-left: 20px;">"We had to be really careful," Schmidt told St. Louis Public Radio. "We couldn't disturb anything at all, because at that point, it was under law enforcement investigation. They were telling us, 'Don't even make footprints,' and I was thinking, 'How are we supposed to do that?'"</p><p>Another difficulty was the mammoth size of the skull: about 7 feet long and more than 3,000 pounds. (For context, the largest triceratops skull ever unearthed was about <a href="https://www.tandfonline.com/doi/abs/10.1080/02724634.2010.483632" target="_blank">8.2 feet long</a>.) The skull of Schmidt's dinosaur was likely a <em>Triceratops prorsus, </em>one of two species of triceratops that roamed what's now North America about 66 million years ago.</p>
Credit: David Schmidt / Westminster College<p>The triceratops was an herbivore, but it was also a favorite meal of the T<em>yrannosaurus rex</em>. That probably explains why the Dakotas contain many scattered triceratops bone fragments, and, less commonly, complete bones and skulls. In summer 2019, for example, a separate team on a dig in North Dakota made <a href="https://www.nytimes.com/2019/07/26/science/triceratops-skull-65-million-years-old.html" target="_blank">headlines</a> after unearthing a complete triceratops skull that measured five feet in length.</p><p>Michael Kjelland, a biology professor who participated in that excavation, said digging up the dinosaur was like completing a "multi-piece, 3-D jigsaw puzzle" that required "engineering that rivaled SpaceX," he jokingly told the <a href="https://www.nytimes.com/2019/07/26/science/triceratops-skull-65-million-years-old.html" target="_blank">New York Times</a>.</p>
Morrison Formation in Colorado
James St. John via Flickr
|Credit: Nobu Tamura/Wikimedia Commons|
The Persian polymath and philosopher of the Islamic Golden Age teaches us about self-awareness.
Can computers do calculations in multiple universes? Scientists are working on it. Step into the world of quantum computing.
- While today's computers—referred to as classical computers—continue to become more and more powerful, there is a ceiling to their advancement due to the physical limits of the materials used to make them. Quantum computing allows physicists and researchers to exponentially increase computation power, harnessing potential parallel realities to do so.
- Quantum computer chips are astoundingly small, about the size of a fingernail. Scientists have to not only build the computer itself but also the ultra-protected environment in which they operate. Total isolation is required to eliminate vibrations and other external influences on synchronized atoms; if the atoms become 'decoherent' the quantum computer cannot function.
- "You need to create a very quiet, clean, cold environment for these chips to work in," says quantum computing expert Vern Brownell. The coldest temperature possible in physics is -273.15 degrees C. The rooms required for quantum computing are -273.14 degrees C, which is 150 times colder than outer space. It is complex and mind-boggling work, but the potential for computation that harnesses the power of parallel universes is worth the chase.