The paper Trends in serious head injuries among cyclists in England: analysis of routinely collected data, by Adrian Cook and Aziz Sheikh (BMJ 2000; 321: p.1055), and the accompanying editorial by three American doctors, has been slammed as bad science by all of the letter writers so far published on www.bmj.com. A selection of these letters will make it onto the BMJs letters page in the next week or so.
Dr Conor Linstead, a researcher from London, said: From the data presented by Cook and Sheik, it cannot be inferred that the reduction in head injuries over the study period relative to the total number of cyclist injuries indicates a correlation between wearing cycle helmets and a reduced incidence of head injuries. The data are insufficient to draw this conclusion.
Avery Burdett, a researcher into cycling accidents, said: The authors refer to lack of controls in other studies but it appears their own study lacked a few of its own. He went on to list three very useful websites with lots of helmets stats:
This showscyclists in Western Australia over a two decade period experienced declining head injury percentages similar to other road users, substantially because of a series of driver behaviour modification measures imposed by the government.
More such effects of Australian bicycle helmet legislation can be found at:
Additional sources are on The Bicycle Helmet FAQ at:
Aedan McGhie, a biology teacher, from Glasgow, warns researchers not to be too reliant on helmet statistics: Four years ago I was cycling to work and was hit by a car coming out of a side road. I of course leapt off the road and inspected my mount for damage. I then noticed blood pouring onto the road so I went to Monklands hospital to get stitched up.
In the admissions area I was asked if I was wearing a helmet. It so happend that I was but only because it was February and polystyrene is decent insulation. I told them that yes, I had been wearing one but as I had landed on my chin it wasn't important. I told them this several times. Nonetheless, if stats were kept of this admission it will be recorded as one where a cyclist was hit by a car and survived while wearing a helmet.
The segregate cyclists from motorists tack was taken by Glenn Stewart, a health promotion advisor, from London:
In Odense (Denmark) approximately 45% of 25 year olds cycle to work everyday and 70% do so in the summer. Almost no-one wears a helmet. Instead they have built a comprehensive system of segregated cycle lanes through which the whole population can undertake the levels of physical activity recommended for good health.
Regardless of the debatable effects of helmets would it not be more useful to focus on changing the environment that makes people feel that they need to protect themselves whilst engaging in healthy behaviour?
Richard Keatinge, a GP trainee rom Wales, was scathing of the papers conclusions:
The simplistic supposition that helmets are responsible for the reduction is quantitatively absurd; among secondary schoolchildren the reduction of head injuries is given as 12%, while the increase in helmet wearing is only 10%. Do Cook and Sheikh really wish to suggest that helmets give protection even when they are not being worn?
It is clearly ridiculous to suggest that Cook and Sheikh have demonstrated any causal relationship. Whatever the time trends in either helmet use or head injury may be, this paper does nothing to illuminate their relationship. I cannot even suggest that the paper is interesting; Cook and Sheikh have presented some extraordinarily dull data, from which no useful conclusions at all can be drawn.
[The authors of the BMJ editorial] have written an editorial marked more by enthusiasm than by a spirit of scientific inquiry. It is not clear that they have checked the arithmetic of Cook and Sheikh.
Keatinge is no fan of cycle helmets:
Helmets are also expensive and uncomfortable; it is hardly surprising that they seem to reduce healthy exercise. Cycle helmets seem to offer no advantages to the public health.
The real issue is the dangerous state of the roads, almost entirely due to the ill-managed use of cars. This is a problem of systems not of individuals; the system includes the majority of doctors (and, sadly, myself) who drive cars regularly, but might like to be fitter and healthier. Blaming individual victims by asking them to wear helmets is not a useful answer to a serious problem. Perhaps the BMJ should invite experts such as Mayer Hillman, Robert Davis, or John Adams to review the evidence and suggest editorial conclusions?
Colin Guthrie, the cycling GP who gets around Glasgow on a trike (see Bike Culture), thinks motorists should be forced to wear helmets and believes in the risk homeostasis theory:
Why are helmets not compulsory for drivers of motor vehicles? I believe that cyclists would be at far less risk if seat belts were illegal and every car had a dagger placed strategically at the centre of the steering wheel and pointing at the driver's chest.
When you are being bombed you don't hide in air raid shelters, you stop the bombing.
He then, colourfully, provided a cycling rap.
Put plenty of whooomph into the YAH...HOOO bit, he advises.
Yah..HOO The time is right.
Im on the bike , Im moving well
Im really in charge, the cars can tell
These days in the saddle are such a treat
Im buzzing from my head to the tips of my feet
Yah ---Hooo ! The energy's flowing
It feels so good, dont care where Im going
Yah---- Hoo ! Get outta my way!
Now just you listen to what I have to say
The time has come , the time is right
Its time for us to stand and fight
Our streets destroyed , so many taken
Its time for us to really shake 'em
Yah---Hoo! Cmon and shout
Its time to get the heavy metal out
Yahhoo! We must be free
From all this vile machinery
Nought to sixty, it makes me sick
Why does size matter to a driver's dick?
If you buy a Peugeot, watch your back
Your woman can expect a shark attack?
Yahhoo! Car culture crap!
A culture that we need to scrap
Yahhoo! We should be free
From all this vehicular insanity.
Keep on cycling..without it you're dead.... helmets would really.....
'knock it on the head.'
Let the red lights roll! Yah...Hooo!