(Update 12/2/2022. The skeptical cardiologist now wears a bike helmet.)
Several weeks after the skeptical cardiologist crashed his bicycle riding in Forest Park and experienced non-cardiac chest pain, he climbed back in the saddle again and rode the route that had resulted in his calamitous fall.
This time, I avoided the mysterious path less traveled.
As I approached Washington University an elderly man riding a bike and wearing a bike helmet came up beside me. He was clearly very irritated by the fact that I was not wearing a bike helmet and kept gesticulating at his helmet to indicate that this was the proper choice of headgear.
I had, as is my usual practice, chosen not to wear a helmet and this man had taken it upon himself to nonverbally lecture me on what he perceived was inappropriately risky behavior.
As I continued my ride I began ruminating on my decision to engage in bike riding without a helmet and wondering if I was being like my patients who continue to smoke cigarettes despite my warnings of the health consequences of that behavior.
There can only be two reasons for an educated person not to wear a helmet:
1. S/he believes there is no or insufficient evidence that wearing a bike helmet will reduce their risk of serious head injury while riding.
2. S/he accepts that helmet-wearing reduces injury but is willing to accept this risk because not wearing the helmet is more pleasurable or convenient.
Similarly, my cigarette-smoking patients may either reject the (overwhelming) evidence of the dangers of this behavior or they may believe it is dangerous but feel that smoking is so pleasurable they decide to continue.
Not wearing a bike helmet lacks the addictive element that cigarette smoking contains but otherwise I think it is a reasonable analogy.
Do Bike Helmets Reduce Injury ?
Despite widespread public health advice to wear bike helmets, I have maintained that evidence for bike helmets reducing injury is lacking.
I’ve spent a fair amount of time since this gentleman upbraided me for being helmet-less reviewing the data again. I was prepared to regularly wear one if the data supported it. But it doesn’t.
A commonly cited statistic is that bike helmets reduce serious head injuries by 85% and brain injuries by 88%. This comes from an observational study published in 1989 which has serious limitations and has never been reproduced. For an exhaustive critique of these data see here.
Cowritten by David Spiegelhalter, the Winton professor for the public understanding of risk at the London School of Hygiene, the editorial was commenting on a paper in the same issue which reported that a Canadian mandatory bike helmet law had minimal effect on cycling-related head injuries.
The writers note that this contradicts previous observational studies which have suggested a benefit from helmet wearing. Like all observational studies, these bike helmet studies 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
- Observational studies cannot account for confounding variables that are unmeasured. For example, people who choose to wear bike helmets may be more cautious than those who don’t and so less likely to have a serious head injury regardless of wearing a helmet. (A 1997 study found that adolescents who smoked cigarettes were more likely to use smokeless tobacco, have multiple sexual partners, and not use bicycle helmets)
Many states and countries have passed laws mandating helmet-wearing but people who are forced by legislation to wear a bike helmet may wear it in a sloppy, ineffective manner. Their behavior may also change through “risk compensation” wherein they behave more irresponsibly in the belief that they are protected from injury.
A single study has also reported that car drivers give a larger clearance to cyclists without a helmet.
I have concluded that my not wearing a bike helmet is due to a lack of evidence to support the health consequences of that behavior. This happens to perfectly align with my disdain for bike helmets which chafe my forehead, make my head sweat and reduce my ability to hear (both charming and lethal) things.
Do Cigarettes Cause Death?
Cigarette smokers, on the other hand, can find no serious scientist or physician who is not convinced of the danger of this lethal habit because the scientific data are overwhelming. The CDC estimates cigarette smoking is responsible for 480,000 deaths per year and that it causes 90% of lung cancers and 80% of chronic obstructive lung disease. The only possible explanation for continuing is the element of addiction combined with the pleasure obtained from smoking.
Public Health Laws: Bike Helmets and Cigarette smoking
Australia and New Zealand are the only countries to have mandatory helmet laws. In the US, according to helmets.org, bike helmets for youths are mandatory in 22 states.
In St. Louis County, they are mandatory for children under the age of 17. In some St. Louis municipalities (Creve Couer for one) they are mandatory for all age groups.
To date, there is no evidence that mandatory bike helmet laws reduce head injuries so why are they being passed?
On the other hand, the dangers of cigarette smoking are clear and there are no countries or states which make it illegal.
To those who would shame we non helmet wearers, I say: “Spend your time shaming those who smoke cigarettes.”
By the way, whenever public policy doesn’t seem to correspond to the evidence, we should look for bias and special interests.
It’s obvious in the world of tobacco that the bias and special interest toward allowing smoking comes from the tobacco industry.
In the cycling world, the bias and influence comes from the manufacturers of bike helmets.
Helmet free and loving it
N.B. As mentioned in the update of this 2017 post, the skeptical cardiologist has caved and wore a bike helmet on a regular bike yesterday (12/1/2022)