Hair trumps helmet

By John Pickering 21/07/2012

Christchurch city councilor and Canterbury Health Board member Aaron Keown is on another crusade.  This time he wants the bicycle helmet law repealed because “Putting a lid on your head messes up your hair, and for a lot of people that is an issue,”  (see here ).
“Vanity, vanity, everything is vanity”
and that should be the end of it, if he wasn’t serious.  He is.  He thinks the look of a helmet and the cost is stopping Christchurch become the Amsterdam of the South Pacific.  Having lived and worked in Amsterdam, I can think of many reasons, not least being driver behavior, why we won’t emulate that city. As for being put off cycling, nothing is morre disturbing than having fat bottomed cyclist zooming past you on the cycle path in skin tight lycra.  Ban lycra I say…thousands more will dust off the old treadly and all will be well.
Having said all that, Mark #18, commenting on the Press web said states “Aaron Keown has some good science to support his case: But never let science and logic get in the way of so-called “common sense” – especially when “common sense” is supported by anecdotes.”   OK then, let’s see what that “good science” is.  The web page quoted has No science whatsoever on it.  It links to one and one only paper from a science journal, namely the NZ Medical Journal of February 2012 . That sounds promising, so let us look at that article. I regularly get to referee articles for inclusion in medical journals, so I shall apply the same scrutiny to this one.
Evaluation of New Zealand’s bicycle helmet law
Colin F Clarke
NZMJ 10 February 2012, Vol 125 No 1349
The first thing that strikes me is that it is an “evaluation” rather than trial or systemic review.  That is, it is some word of (expert) opinion.  Fine, journals have those kinds of articles all the time.  They are worth reading if the person writing them really has expertise (see the end of the article and judge for yourself if Colin Clarke is really expert or not). They should not be talked about, though, in the same breath as a clinical trial or systemic review or metaanalysis.
The second thing that strikes me as I read through is that is is full of numbers used to support the author’s opinions, but there are no statistics at all to back this up.  My PhD students would get a flea in the ear if they tried to present a differrence in means to me as meaningful without backing it up by the appropriate statistical test which tells me how likely the difference is to be real rather than random variation.  I would not agree to publication of any article that looks at relative risk, as Colin Clarke does without presenting 95% confidence intervals so that I could see if a relative risk of, say, 2.4 was really differnt from 1.  ie was the risk of death by cycling really 2.4 times that of walking? If the 95% confidence interval straddles zero (eg 95%CI -0.6 to 5.4) then the answer is “probably not.” Without that information,
“Meaningless, meaningless, everything is meaningless.”
Mr Clarke’s conclusions are just that. Furthermore, he makes the mistake of assuming that changes in incidences of death or injury since the advent of the helmet are because of the helmet.  He does not account for other changes including the lightness and speed of bikes, the greater density of cars on NZ roads etc etc etc.
Sorry Mark #18, this is defininetly NOT good scientific evidence.  As a scientists in a university Department of Medicine in New Zealand, I am ashamed that the NZ Medical Journal should allow such poor science to be published.
I am aware there is some research on the issue in other jurisdictions.  It is not so overwhelming as to have resulted in comissioned studies in NZ, let alone a change of law. Certainly vanity is not a reason to trump safety.  In the meantime, Cr Keown, I expect better of someone on the CDHB health board.  We have many issues on this city that are much more important. Drop this one and get on with your job

Tagged: bicycle, helmet, Risk