Re: Rise in injury rates for older male motorcyclists

The article “Rise in injury rates for older male motorcyclists: An emerging medical and public health concern” in the October issue (BCMJ 2014;56:386-390) raises many interesting points, and I applaud [the editor] and the authors for drawing attention to some of the issues involved.

However, although I am neither a mathematician nor statistician, I believe that the title is fundamentally misleading. In order to calculate a rate, two items must be compared. In this case, one is the number of motorcyclists on the road and the other is the number of these motorcyclists who are involved in accidents. The article deals with the second of these numbers, but does not address the first. To illustrate my point, consider the following hypothetical example. If, between 2001 and 2010, the number of motorcyclists on the road between the ages of 45 and 74 had doubled, the 2013 motorcycle-related injuries mentioned in the article would in fact represent a decrease in the rate at which those riders were involved in injuries, not an increase, as the article claims.

Without data referring to the actual number of riders between the ages of 45 and 74 (demographic data which, perhaps, is readily available from ICBC files, as all of us have to buy licence plates at some time), I do not understand how the authors can conclude that there has been a rise in injury rates. Raw numbers, yes, but rates, no.

In addition, while the hospitalization cost of these accidents is said to have increased by 61% in the same period, the figure is meaningless unless compared with increased hospitalization costs in general.

Much still needs to be done to educate riders about motorcycle safety and, incidentally, to educate car drivers about turning left in the path of an oncoming motorcycle, which is where a large proportion of motorcyclists come to grief. But before we decide where to invest our efforts in this direction, we need a more careful look at the data.
—Barry Munn, MD
Nanoose Bay