A CRITICAL EXAMINATION OF THE HAGEL REPORT ON HELMET USE
Hagel BE, Rizkallah JW, Lamy A, Belton KL, Jhangri GS, Cherry N, et al.
Bicycle helmet prevalence two years after the introduction of mandatory
use legislation for under 18 year olds in Alberta, Canada.
Inj Prev 2006;12(4):262-265. Abstract
The report compares two separate sets of data from observations in years 2000 and 2004 to determine changes in helmet wearing rates before and after Alberta's child helmet law which was implemented in May 2002. Using a project co-ordinator to direct two observers in 2004, the study method differed from year 2000 in that not all cyclists passing observation check points were counted. It is not clear why Hagel et al didn't use the same method as it has prevented a direct evaluation of the law's effect on cycling participation. Instead, they compared proportions of cyclists wearing helmets for the two years. Based on the results, the authors recommended that Alberta extend it's current child-only helmet legislation to cover adults.
This critique of the report examined the breakdowns of cyclists affected by the law (children under 18 years of age) and those not affected (adults) and found a strong indicator that child cycling declined significantly.
In year 2000, 164 (26%) of the 638 cyclists observed were children. At the same sites at the same time of the year in 2004, only 41 (15%) of 271 cyclists observed were children. Applying the authors' own statistical technique, it can be concluded there has been a drop of 42% in the proportion of children cycling. The question arises from this is "did the authors knowingly overlook this indication of a decline in child cycling because their case for extending the law to adults was already weak?"
Another disturbing aspect of this report is the authors' choice, and selective use, of comparative data to justify extending the helmet law to adults. They used Toronto's experience of child cycling mostly during the 1990's rather than Alberta's more current experience. Toronto's result was based on data concerning children under 15 years of age - not children under 18 years of age that are covered by Alberta's law. Added to these limitations, was an irrelevant group comparison.
Hagel et al say "considering that children riding with helmeted adults are almost 10 times more likely to be wearing a helmet than children riding with nonhelmeted child companions, policy makers should consider extending current children-only helmet legislation in Alberta and other locations". There is a problem with this logic. In considering such an extension, the relevant helmet use comparison is not with non-helmeted child companions, after all they are already subject to Alberta's law. The correct comparison is with non-helmeted adult companions. While these data were available in the cited Toronto report and produce a figure of just under 2.5 times more likely, more recent and pertinent companion data were available to the authors from a chart in the year 2000 observations in Alberta. It shows that the helmet wearing rate of children riding with non-helmeted adults was 84%, whereas when riding with helmeted adults it was 99%. Thus children were only 0.15 times less likely to wear helmets when riding with non-helmeted adults. The significant difference of this likelihood compared to the authors' "10 times more likely" from an irrelevant comparison is a serious error. This reinforces the argument that the case for adding coverage of the law to adults is weak.
The authors also claim that the police used minimal enforcement. They say that 48 helmet infraction tickets were issued in 2004. Since children under age 16 cannot be charged in Canada, the tickets must have been issued to 16 and 17 year olds, (assuming they were not wrongly issued to younger children). According to recent correspondence between the Vehicular Cyclist and the Edmonton Police Service, two additional tickets were issued to parents for knowingly allowing their children to ride without helmets. Fifty tickets is an insignificant number given that observers in 2004 counted only 7 non-helmeted children at 22 separate locations! Since Edmonton police officers have discretion in writing tickets, what likely happened was that ticketing was combined with an educational approach. Knowing that they couldn't charge non-helmeted children, officers gave them stern verbal warnings. This would have the same effect as enforcement. The author's conclusion that the increase in the rate of helmet use is not due to enforcement cannot be substantiated. A non-ticketing form of enforcement cannot be ruled out and could be responsible for the 42% drop in proportion of child cyclists.
Given the strong indications of a decline in child cycling following introduction of Alberta's helmet law and given the irrelevance of the authors' companion cyclist comparison, the report cannot be considered a credible basis for arguing the extension of helmet laws to adults. On the contrary, the probable decline in child cycling (partly from some police enforcement) casts doubt on the legitimacy of Alberta's law. Since evidence of reduced rates of head injury have yet to be attributed to Alberta's law, and the only data published since the law was implemented showed an increase in the child head injury rate, there is a strong case for repealing Alberta's existing child helmet law.