Worldwide helmet concerns
The article by Macpherson et al relies on surveys from 111 sites around East York (Toronto) and some questions remain about these surveys. Data from two reports provides confusing indications on the level of cycling. In 2001 figures were published for the hourly rate for several years and by comparison in 2003 counts for 8-years were provided based on 1 hour observation at each site. An hourly rate is calculated base on the 111 sites and 1 hour per site ,'A' divided by 111. The table below shows the data;
Table 1 * data from 2003, 568 wearing helmets from 1227 is 46%, not 45 % as quoted in ref 1.
Robinson  stated "The Canadian study had 111 pre-selected sites, each recorded for one hour, but weather conditions were not reported (though elsewhere 1999 was described as a particularly sunny summer; A K Macpherson, personal communication). Table 1 in the Macpherson et al paper shows that, in some years, some sites were recorded more than once. Moreover, observations were not at the same time of day and day of the week each year (A K Macpherson, personal communication)"
A number of aspects arise,
1) Can extra count details be added to the table, for 1999 and 2001.
2) Why the counts for years 1993 to 1997 were quite different in the published reports.
3) Why the total hours of surveys calculated should vary from 112 hours to 425 hours.
4) Why the observation hours were not a multiply of 111, as per number of sites.
5) Which survey details would be more likely to reflect the true level of cycling activity, 2001 or 2003, if either.
6) Could there have been an 17% drop in cycling, 2003 data - average count pre law 1275, post law 1059.
7) Can other data be added to the table.
8) How reliable are the surveys for indicating the overall level of cycling activity for those aged to 19 years.
9) Helmet use of 46% before legislation is identical to that in 2001 at 46%, seems like no appreciable effect from legislation.
Extra information would help provide a clearer picture to be guided by and most appreciated.
1. Macpherson AK, Macarthur C, To TM, et al. Economic disparity in bicycle helmet use by children six years after the introduction of legislation. Inj Prev 2006;12:231-235
2. Macpherson AK, Parkin PC, To TM. Mandatory helmet legislation and children’s exposure to cycling. Inj Prev 2001;7:228–30.
3. Parkin PC, Khambalia A, Kmet L, et al. Influence of socio-economic status on the effectiveness of bicycle helmet legislation for children: a prospective observational study. Pediatrics 2003;112:e192
4. Robinson DL, Helmet laws and cycle use, RESEARCH LETTER, Inj Prev 2003;9:380-381
Timely reporting, concurrent comparisons and common sense
Changes in %HI unrelated to %HW
Common sense tells us that if the reduction in head injuries were due to helmet laws, percent head injury (%HI) should decline in response to the increase in percent helmet wearing (%HW).
Fig 1 shows this was not the case either in Ontario or British Columbia (BC), two provinces containing 90% of the population of helmet-law provinces in Canada. The greatest decline for BC was a fall of 7.4 percentage points from 94/95 to 95/96 (before the law was enacted). The greatest decline for Ontario (5.4 percentage points) was from 96/97 to 97/98, when helmet wearing was also declining.
The more recent data for Ontario confirm the lack of relationship. The downward trend continues, despite a return to pre-law helmet wearing by 1999. The lowest %HI was for 01/02 when helmet wearing had returned to pre-law levels.
The lack of relationship between %HW and %HI would convince most people that Canada's helmet laws had little benefit, so it is difficult to understand why Macpherson et al. continue to claim:
a) that the data from 94/95 to 97/98 show the laws were effective and
b) we can't draw any useful conclusions from the more recent data, because there is no "concurrent comparison group".
Other road safety measures
Even with "concurrent comparison groups", common sense is needed to interpret them correctly. Fig 2 shows a greater declining trend in fatal and serious pedestrian injuries in helmet-law provinces than no-law provinces. The divergence in pedestrian trends obviously wasn't caused by helmet laws. So it seems illogical to claim the trends in %HI (which bear no relationship with the timing of the laws) demonstrate that the Canadian legislation was effective. The trends could have had similar underlying causes (e.g. safer roads) rather than those for cyclists being due simply to helmet laws.
Although bike/motor vehicle collisions (BMVC) cause only a small proportion of total injuries to cyclists, a study of all brain injuries to cyclists in an entire year in San Diego county found that BMVC caused every single fatal or seriously debilitating brain injury. Overall road safety is therefore a major determinant of the risk of debilitating head injury.
A peer-reviewed paper in 1996 showed very strong relationships (r = 0.94, P <_0.02 between="between" hi="hi" of="of" child="child" cyclists="cyclists" and="and" pedestrians="pedestrians" in="in" victoria="victoria" australia.7="australia.7" fell="fell" from="from" _18.3="_18.3" the="the" year="year" before="before" helmet="helmet" law="law" to="to" _10.7="_10.7" second="second" legislation="legislation" compared="compared" a="a" decline="decline" _15.6="_15.6" _13.5="_13.5" for="for" cyclists.7="cyclists.7" greater="greater" strongly="strongly" suggests="suggests" main="main" cause="cause" was="was" not="not" law.="law." p="p">These results supersede those of Cameron et al. (1994). I cannot understand why Macpherson's response to Wardlaw still cites Cameron as evidence that Victoria's helmet law "was effective in reducing head injuries", instead of later research pointing out the significant effects of reduced cycling and large declines in %HI of pedestrians.Timely reporting of results
Finally, Malcolm Wardlaw is correct that timely and accurate reporting of results is important. Numbers counted in the 1999 Ontario survey were published in 2001, but helmet wearing rates for the same year (1999) were not published until August 2006. If, as Macpherson say, she agrees that timely reporting is important, why was the vitally important information that helmet wearing rates returned to pre-law levels by 1999 not mentioned earlier?
If, in 2005, the BMA had known that enforcement in Ontario was ineffective and %HW was at pre-law levels from 1999 onwards, as well as that (as Fig 1 shows) neither the timing of helmet laws nor the changes in %HW bear any relationship with the trends in %HI, their stance on helmet legislation laws might have been different.References
1. Transport Canada. Road Safety in Canada - 2003. Report prepared for the Canadian Council of Motor Transport Administrators (CCMTA) Standing Committee on Road Safety Research and Policies: Road Safety and Motor Vehicle Regulation Directorate (available at:http://www.tc.gc.ca/roadsafety/tp/tp13951/2003/pdf/tp13951%20EN-S.pdf), 2006.
2. Macpherson AK. An evaluation of the effectiveness of bicycle helmet legislation (powerpoint presentation, available at http://www.circl.pitt.edu/home/webinars/ppt/macphersonwebinar.ppt), 2006.
3. Macpherson AK, Parkin PC, To TM. Mandatory helmet legislation and children's exposure to cycling. Inj Prevent 2001;7(3):228-30.
4. CIHI. Injury Hospitalizations (includes 2000-01 and 2001-02 data): Canadian Institute for Health Information, 2003.
5. Macpherson AK, Macarthur C, To T, Wright J, Chipman M, Parkin P. Reply to Mr. Wardlaw's letter "Timely reporting of research is necessary": E-letter, Injury Prevention http://ip.bmj.com/cgi/eletters/12/4/231#1667, 2007.
6. Kraus JF, Fife D, Conroy C. Incidence, severity, and outcomes of brain injuries involving bicycles. Am J Public Health 1987;77(1):76-8.
7. Hillman M. Health benefits of cycling greatly outweigh loss of life years from deaths. BMJ 1997;314:69.
8. Cameron MH, Vulcan AP, Finch CF, Newstead SV. Mandatory bicycle helmet use following a decade of helmet promotion in Victoria, Australia--an evaluation. Accid Anal Prevent 1994;26(3):325-37.
Reply to Mr. Wardlaw's letter "Timely reporting of research is necessary"
In his letter "Timely reporting of research is necessary", Mr Wardlaw suggests that lack of enforcement of bicycle helmet legislation in Ontario is an underreported aspect of bicycle helmet research.
Although the issue of enforcement of legislation has been raised as a potentially important aspect of bicycle helmet laws, to our knowledge, no one has studied the nature of enforcement of helmet legislation in Ontario (or elsewhere). A single police force in Ontario (Toronto Police Services) has no record of charging a child for not wearing a helmet, there are many ways that the police can enforce legislation that do not include the police issuing citations. For example, the police can warn children verbally that there is a helmet law. Further, Toronto Police Services routinely work with schools to promote safe bicycling in the form of Bike Rodeos. All children must ride helmeted at these events.
Many other ways of ‘enforcing’ laws exist, particularly for laws aimed at children. Laws give parents, teachers, and other adults the authority to promote certain behaviours in children. Many parents are grateful for the helmet law, because the requirement to wear a helmet is not based on their decision, but on a societal choice. They can therefore enforce the law within their own family. Further, school principals often require that children wear helmets bicycling to school because "it is the law". These are just two examples of ways that helmet laws have been enforced in Ontario, but their measurement is beyond the scope of the published study. The unit of analysis in our study was observed children, not their parents or teachers, and we did not measure their knowledge of the law.
Mr. Wardlaw comments on the decline in hospitalizations for head injuries in Ontario <1>. Administrative data are helpful in assessing trends in hospitalizations, but they do not measure factors such as helmet use. The report cited by Mr. Wardlaw measured hospitalizations which have been declining for many reasons, including changes in practice patterns for admission of head injuries. There is no concurrent comparison group with which to compare these trends. Although evidence from systematic reviews suggests that helmets are effective in reducing head injuries <2,3>, we do not know whether children admitted to hospital for bicycle-related injuries in Ontario were helmeted or not. The distribution of helmet use among admitted children is one key (unmeasured) factor that is necessary to understand the population impact of helmet laws.
In conclusion, we agree that timely reporting of results is necessary. We also believe that research results reported in the peer reviewed literature must be based on scientific evaluation of risk factors considered within the study design. Helmet laws have been shown to be effective in reducing head injuries in published studies from around the world <4,5,6,7,8>. Our study did not measure enforcement of the helmet law in Ontario.
1. "Bicycle-related injuries among Ontario children declining". Canadian Institute for Health Information. http://secure.cihi.ca/cihiweb/dispPage.jsp?cw_page=media_19mar2003_e
2. Thompson DC, Rivara FP, Thompson R. Helmets for preventing head and facial injuries in bicyclists (Cochrane Review). In The Cochrane Library, Issue 3, 2000. Oxford: Update Software
3. Attewell RG, Glase K, McFadden M. Bicycle helmet efficacy: a meta -analysis. Accident Analysis & Prevention 2001;33:345-52.
4. Scuffham P, Alsop J, Cryer C, Langley JD. Head injuries to bicyclists and the New Zealand bicycle helmet law. Accident Analysis & Prevention 2000; 32:565-73.
5. Macpherson AK, To TM, Macarthur C, Chipman ML, Wright JG, Parkin PC. Impact of mandatory helmet legislation on bicycle-related head injuries in children: a population-based study. Pediatric 2000; 110:e60.
6. Cameron MH, Vulcan AP., Finch CF, Newstead SV. Mandatory bicycle helmet use following a decade of helmet promotion in Victoria, Australia-- an evaluation. Accident Analysis & Prevention 1994; 26:325-37.
7. Leblanc JC, Beattie TL, Culligan C. Effect of legislation on the use of bicycle helmets. CMAJ Canadian Medical Association Journal 2002; 166:592-5.
8. Shafi S, Gilbert J, Loghmanee F, Allen JE, Caty MG, Glick PL, Carden S, Azizkhan RG. Impact of bicycle helmet safety legislation on children admitted to a regional pediatric trauma centre. J Pediatr Surg 1998;33:317-321.
Re: Re: Timely release of information is important.
In his zeal to defend bicycle helmet laws, Editor Barry Pless ignored two important issues identified by Malcom Wardlaw and in doing so raises one of even more vital importance.
First, child cyclist head injuries declined in Ontario while data from Macpherson showed a declining rate of bicycle helmet use. This suggests a factor other than helmet use and helmet laws was responsible for the decline in head injuries. Second, the authors of the 2001 Injury Prevention study which concluded that Ontario's helmet law had not negatively impacted levels of cycling, however they were aware but failed to mention two critical factors in evaluating the effect of helmet laws - (a) within four years the law had reached a null impact on helmet use, and (b) the lack of police enforcement.
In an editorial, Pless has admitted his own biases and sensitivities in dealing with issues concerning bicycle helmets and Macpherson recently appeared in the Ontario Legislature in support of a motion to impose a helmet law on adults. Such activism raises questions about whether personal biases are taking priority ahead of scientific findings and criticisms.
Pless says that he struggles to understand why Wardlaw and others work so consistently to oppose helmet legislation. This is an astonishing statement given Wardlaw along with Robinson, myself and others restrict ourselves to questioning the science upon which helmet laws are based. If Pless doesn't understand the fundamental objection to having the state unjustifiably impose a requirement on its citizens, then what he's really saying is that he struggles to understand human nature.
Please, let's restrict ourselves to facts. Political activism doesn't belong in a scientific journal.
1. Pless B, Are Editors free from bias? The special case of Letters to the Editor, Inj Prev 2006 12: 353-354. doi:10.1136/ip.2006.014472
2. Hansard, Legislative Assembly of Ontario, 14 December 2006
Re: Timely release of information is important.
Malcom Wardlaw asks if a serious head injury rate of 1 per 7,000 capita per year is great enough to warrant enforced use of protective headgear. My view is that there is no magic number; even 1 per 70,000 would be too many if the injury had serious sequelae, as undoubtedly many do. I am certain most sensible parents and most pediatricians who treat these children would agree. The opinions of the City of Toronto Police Service and even that of "most of Ontario society" (which, apparently Wardlaw has knowledge of) is entirely irrelevant. Police in my city fail to enforce speeding, red light, and stop sign violations. Why safety is not their priority remains one of life's great mysteries. It is hardly surprising then that the authors did not discuss other reasons for lack of enforcement. If Wardlaw cares to speculate on what he believes these reasons to be, he should do so.
The decline in head injury admissions noted by Wardlaw only serves to reinforce the need to enforce helmet legislation, not, as he implies, to abandon it. The BMA's reversal of its position indicates that it agrees with this reasoning. Moreover, to suggest that without enforcement laws are "at best, ineffective..." flies in the face of much evidence to the contrary. Laws work even when unenforced; they work better when enforced. It is as simple as that.
How it is possible for Wardlaw to know what the BMA assumed is beyond my comprehension, as is the confused logic in the sentence in which this assertion appears. Nonetheless, I continue to struggle to understand why Wardlaw and others work so consistently to oppose helmet legislation. And, by the way, I struggle to understand how or why "timely release" figures into the argument.
Timely release of information is important.
Macperson et al. present valuable findings  on rates of helmet use by Toronto children of different income groups; and how these rates varied across a period in which a helmet law was passed. The wearing rates rise to a peak after the law of 1995, followed by a decline back to roughly pre-law levels by 1999. This profile occurred because the law was not enforced. The City of Toronto Police Service confirmed in 2004 that no child cyclist had been ticketed for not wearing a cycle helmet in that city.
This history raises two issues that warrant further discussion:
1) Risk in cycling:
The principal cause of head injuries to Canadian children is falls, followed by pedestrian road accidents. There are about six million Canadians aged 5-19, amongst which an average of 2,200 were admitted to hospital annually between 1994 and 1998 following a cycling crash. 35% had head injuries. This is a (serious) head injury rate of 1 per 7,000 capita per year. Is this injury rate great enough to warrant enforced use of protective headgear? The City of Toronto Police Service, and most of Ontario society, apparently thought not.
The authors did not discuss reasons for the absence of enforcement. Their commentary is limited to: “Finally, the role of law enforcement was not studied; therefore its impact could not be assessed”. Their data make it clear that enforcement is required to sustain helmet use above what is found in voluntary jurisdictions. This is a useful piece of knowledge in the debate on helmet legislation.
A report issued by the Canadian Institute for Health Information revealed that between 1997/98 and 2001/2, Ontario child cyclist hospital admissions declined by 12.5%, but head injury admissions specifically declined by 26%. This advantageous outcome occurred in a period in which, the authors report, helmet use declined from a peak in 1996/97 to pre-law levels by 1999. Other evidence reveals that large changes in helmet use have not noticeably improved serious head injury trends at the population level.
2)Timely release of data is important:
In a previous paper of 2001, based on the same dataset, Macpherson et al reported that the introduction of helmet legislation in Ontario had not deterred children from cycling. The authors reported numbers of cyclists counted, rather than the extent of enforcement or helmet wearing rates. However, the conclusion was cited (and still is cited) by influential bodies in support of the introduction of enforced helmet legislation. For instance, the British Medical Association reversed its long opposition to helmet laws and cited the 2001 paper alone in its change of stance:
“In our 1999 report, significant emphasis was placed on the BMA's wish not to discourage cycling by making helmets compulsory. The advice was based on evidence from Australia indicating that cycling levels decreased following the introduction of legislation. The evidence is now outdated ... A study from Ontario, Canada has demonstrated that introduction of helmet legislation did not reduce numbers of children cycling [referenced to Macpherson et al 2001].
“As with any other legislation, enforcement is as important as the law itself. Without compliance, the law is at best ineffective...”
The BMA assumed the research referred to an enforced law, when in fact it referred to an unenforced law, which of course the BMA explicitly did not wish to see. Such confusion would likely have been avoided had the 2001 paper mentioned that the helmet law was not enforced and helmet wearing rates returned to pre-law levels by 1999.
1.Macpherson A, Macarthur C, To T, Chipman M, Wright J, Parkin P. Economic disparity in bicycle helmet use by children six years after the introduction of legislation. Injury Prevention 2006;12:231-35.
2.Personal correspondence with City of Toronto Police Service by A. Macpherson.
3.Canadian Institute for Public Health data, presented at: http://secure.cihi.ca/cihiweb/en/media_30aug2006_tab3_e.html
4.Macpherson A, Teresa M, Macarthur C, Chipman M, Wright J, Parkin P. Impact of mandatory helmet legislation on bicycle-related head injuries in children; a population-based study. Pediatrics 2002;110:60.
5.“Bicycle-related injuries among Ontario children declining”. Canadian Institute for Health Information. http://secure.cihi.ca/cihiweb/dispPage.jsp?cw_page=media_19mar2003_e
6.Robinson DL, No clear evidence from countries that have enforced the wearing of helmets. BMJ 2006;332:722-25.
7.Macpherson A, Parkin P, To T. Mandatory helmet legislation and children's exposure to cycling. Injury Prevention 2001;7:228-30.
8.“Legislation for the Compulsory Wearing of Cycle Helmets”. The British Medical Association 2005. http://www.bma.org.uk/ap.nsf/Content/cyclehelmetslegis
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