Re: Comparing apples with apples? Abusive Head Trauma, Drowning and LSVROs (response to Kaltner, Kenardy, Le Brocque & Page, 2012), by Watt, Franklin, Wallis, Griffin, Leggat and Kimble (2012)
Developing the epidemiological literature base on the occurrence of all forms of childhood injury is essential to the development and promotion of injury prevention efforts. As is rightfully highlighted by Watt, Franklin, Wall...
Re: Comparing apples with apples? Abusive Head Trauma, Drowning and LSVROs (response to Kaltner, Kenardy, Le Brocque & Page, 2012), by Watt, Franklin, Wallis, Griffin, Leggat and Kimble (2012)
Developing the epidemiological literature base on the occurrence of all forms of childhood injury is essential to the development and promotion of injury prevention efforts. As is rightfully highlighted by Watt, Franklin, Wallis, Griffin, Leggat and Kimble (2012), limitations in the availability of easily accessible child injury data exist in Queensland. Within Kaltner, Kenardy, Le Brocque & Page's (2012) paper, published figures on rates of alternate forms of childhood injury were utilised to contextualise the occurrence of Abusive Head Trauma (AHT). Their selection was based on the most recent figures available to the authors following extensive literature searches; as is discussed by Watt et al., more comparable and recent figures are not accessible in the public sphere.
With the cessation of funding to the Queensland Trauma Registry, the availability of up-to-date, reliable injury data within Queensland is limited. This presents a further challenge to all injury researchers in the state, alongside the hurdle of approvals necessary to access Queensland Health data as overviewed by Watt et al. (2012). In undertaking the important work of research and prevention for all forms of childhood injury, high level support-including financial commitment- for the development and maintenance of reliable and accessible injury databases is necessary.
Hemenway (1) describes three beliefs which may jeopardize injury-
avoidance: optimistic ("it will never happen to me"), fatalistic
("accidents happen") and materialistic ("you probably deserved it"). Such
a scheme parallels well-known trait theories regarding the individual's
general personality (2); given the value of those endeavours,Hemenway's
scheme deserves serious consideration.
Hemenway (1) describes three beliefs which may jeopardize injury-
avoidance: optimistic ("it will never happen to me"), fatalistic
("accidents happen") and materialistic ("you probably deserved it"). Such
a scheme parallels well-known trait theories regarding the individual's
general personality (2); given the value of those endeavours,Hemenway's
scheme deserves serious consideration.
Nonetheless, it may be incomplete. In this note, I argue for the
inclusion of values that I label as societal - that is, they are best
understood in terms of major societal groups. Evidence supporting this
proposal resides in a comparison of road-travel and rail-travel; this
suggests that society expects higher standards of safety for rail than for
road. Two examples follow:
A. SAFETY AND VEHICLE DESIGN: Traditionally, Britain's railway
carriages were equipped with slam-doors, which could be opened by
passengers even when the train was moving. During the mid-2000s, such
stock - even if relatively new - was mostly replaced by carriages using
less reliable sliding-doors under electronic control of guard and driver.
The saving in injuries and deaths has almost certainly been miniscule: I
see no evidence against this assertion in Britain's transport data (3).
Society deemed that the relevant legislation should be enacted, despite
the heavy costs involved.
Cost can have different implications on the road: SUVs - large and
powerful four-wheel-drive automobiles - are more dangerous than smaller,
cheaper-to-buy and cheaper-to-run automobiles (4). One might suppose that
governments would seek to reduce the prevalence of SUVs, since the choice
of SUV ownership appears to be little more than an issue of perceived
prestige.
B. ATTENTION TO THE TASK: Society has long expected that train
drivers pay undivided attention to their job. Indeed, the use of a "dead-
man's-handle" or its modern developments entails the train automatically
coming to a stand if the driver diverts attention (5).
In contrast, values concerning the road imply that drivers can safely
carry out other tasks during driving. A notably transparent example
concerns the common media device of televising an inverview while the
interviewee is driving. This presents an extraordinarily inept message to
the motoring community. Inattention on the road is supposedly discouraged,
although specific legislation is limited. The banning of mobile-phone use
is a rare case, but its effectiveness must be seriously doubted (6).
CONCLUSION: Hemenway offers a useful scheme for investigating injury
prevention. I argue here that - at least regarding travel - the problems
are not simply to be understood by reference to the individual's beliefs.
The problems are also societal. The two examples above indicate greater
threat on road than on rail. There are other examples that can be
developed: the use of psychoactive drugs (7,8) and failure to observe
speed-limits (9). Paradoxically, the latter may have been exacerbated by
the legally-required use of seatbelts (10).
The imbalance in societal values is consistent with casualty
statistics (3). Until society is prepared to recognise and implement the
lessons from rail-travel, an important conduit for injury prevention in
road-travel will remain under-exploited.
REFERENCES
1. Hemenway D. Three common beliefs that are impdiments to injury
prevention. Inj Prev 2012;
00:1-4. doi:10.1136/injuryprev-2012-040507
2. Hewstone M, Fincham F, Foster J. Psychology. 2005. Leicester UK:
BPS.
3. Department for Transport 2011. Transport statistics GB: 2010
Annual report. London: TSO.
4. Simms S, O'Neill D. Sports utility vehicles and older pedestrians.
BMJ 2005;331:787-8.
5. Harris M. Dead man's handle. In Simmons J, Biddle G (eds). The
Oxford campanion to British railway history. 2002. Oxford:OUP (p 125).
6. McEvoy SP, Stevenson MR, McCartt AT, Woodward M, Haworth C,
Palmara P, Cercarelli R. Role of mobile phones in motor vehicle crashes
resulting in hospital attendance: a case-crossover study. BMJ 2005;331:428
-430.
7. Perkins A. Red Queen: the authorized biography of Barbara Castle.
2003. London: Macmillan.
8. Hall W. Driving while under the influence of cannabis. BMJ
2012;344:e595 doi: 10.1136/bmj.e595.
We acknowledge that we did not control for all of the differences in
road geometry and building typologies because there are no ideal matched
streets (Re: Cooper). However, alternative research designs also have
limitation and feasibility issues. For before and after study designs,
some of the Montreal cycle tracks are 20 years old, before injury
surveillance and traffic counting data systems were available. Limiting to...
We acknowledge that we did not control for all of the differences in
road geometry and building typologies because there are no ideal matched
streets (Re: Cooper). However, alternative research designs also have
limitation and feasibility issues. For before and after study designs,
some of the Montreal cycle tracks are 20 years old, before injury
surveillance and traffic counting data systems were available. Limiting to
cycle tracks that were developed after these data were available would
limit us to a much smaller number of cycle tracks, thus reducing the
statistical power. Utilizing a multivariate analysis to account for other
factors such as road geometry, buildings types, pedestrians, trees, etc.
would answer a different research question - about the possible
independent effect of each factor - and would require many more cycle
tracks or another unit of analysis (ex. intersections). Therefore,
bicycling on cycle tracks was compared to bicycling on streets without
cycle tracks. To select the alternative reference streets without cycle
tracks, a few parallel reference streets were considered for each street
with a cycle track, The parallel street was then selected because it had,
as much as possible, the same cross streets. Recognizing no perfect
reference street existed, we also compared relative danger from vehicular
traffic by obtaining the injuries to motor vehicle occupants (EMR data).
Given these limitations, none of the 6 pairs were found to have a
statistically significant higher risk of injury on the cycle tracks. Thus,
not one of the comparisons in this research conducted in Montreal
supported the old hypothesis that bicycling on cycle tracks posed greater
risk than bicycling in the road. In fact the opposite was true as
bicycling on the cycle tracks posed less risk.
Our population-based study (1) on the effectiveness of breed-specific
legislation (BSL) targeting pit-bull (terrier) type dogs in the Canadian
province of Manitoba generated some interest in the media and among policy
-makers and the public in Canada and the United States (2-10). With this
experience of listening to different stakeholders and communicating with
some, we hope to elaborate on our findings in language that is...
Our population-based study (1) on the effectiveness of breed-specific
legislation (BSL) targeting pit-bull (terrier) type dogs in the Canadian
province of Manitoba generated some interest in the media and among policy
-makers and the public in Canada and the United States (2-10). With this
experience of listening to different stakeholders and communicating with
some, we hope to elaborate on our findings in language that is accessible
to all. The objective of the study was to determine trends in the
frequency of dog-bite injury hospitalizations (DBIH) over time for
jurisdictions with and without a ban on pit bull (terrier)-type dogs in
Manitoba (1).
We reported that at the provincial level in Manitoba, there was a
decrease in incidence of DBIH from 3.47 to 2.84 per 100,000 person-years
associated with implementation of a ban on pit-bull terrier type dogs.
That is, there was a decrease by 0.63 per 100,000 persons per year (an
18.1% decrease in DBIH rate) in 16 self-selected urban and rural
jurisdictions. Correspondingly, in people aged 0 to < 20 years, there
were 1.76 fewer DBIH per 100,000 person-years (a 25.5% decrease in DBIH
rate) in Manitoba. This decrease in rates of DBIH may be a conservative
finding because enforcement of legislation, which was not measured and is
known to have varied across the jurisdictions and over the years, is
assumed to be minimal, if at all. While the type of legislation studied
was specifically a ban, no jurisdictions were known to have outlawed pit
bulls overnight. As existing individual dogs were allowed to live out
their lifetimes, no drastic reduction in numbers of pit bulls, and by
extension, in numbers of DBIH, was expected in jurisdictions that
implemented bans only gradually since 1990.
What does the change in incidence of DBIH at the provincial level
mean? The Canadian province of Ontario, with a population about 11 times
larger than Manitoba, has a province-wide ban on pit-bull terrier type
dogs since 2005 (11). Assuming that Ontario's DBIH rate, rate of
penetration of dog population (i.e., dogs per capita of human population)
and dog-breed distributions are similar to those in Manitoba, we applied
the decrease of 0.63 DBIH per 100,000 people per year to Ontario's
population of 12.8 million in 2011 (12,13). (While Manitoba's rural
population is considered to be 28%, Ontario's rural population is reported
to be 15%.) We estimate that there may have been 81 fewer DBIH in 2011
alone in Ontario on account of the province-wide ban. As Ontario's
population of those aged < 20 years was 3 million (13), 54 (66.7%) of
the estimated decrease by 81 DBIH among all ages in 2011 would have been
in people aged < 20 years.
When considering rate differences in post-legislation period compared
with pre-legislation period in Winnipeg alone, our data do not indicate a
change in DBIH rate. Therefore, it is natural to assume that BSL does not
work. However, our study does not account for changes in overall number
of dogs over the long period under study. Based on growth in number of
pet dog populations in the United States over the last two decades
(14,15), we propose that any hypothesized decrease in the number of DBIHs
due to pit-bull attacks is likely masked, and the effect of legislation
diluted, by a simultaneous increase in DBIHs due to attacks by dogs from
other breeds or breed groups. Again, this explanation is quickly assumed
to be evidence that breed bans do not work. After all, an argument
against BSL is that breed composition in dog populations can change such
that other dangerous dogs replace dogs from banned breeds. A limitation
of the study was our inability to separate the proportion of DBIHs caused
by dogs of banned breeds from the proportion caused by dogs of other
breeds or breed groups. However, with the assumption that replacement is
necessarily different from addition of more dangerous dogs to the existing
numbers, we compared DBIH rates in jurisdictions with pit bull-specific
ban (e.g., Winnipeg) to DBIH rates in jurisdictions without such bans
(e.g., Brandon). The idea behind this analysis is that, unlike pit-bull
specific bans, voluntary changes in breed popularity have no boundaries,
and jurisdictions with bans are assumed to be similar to jurisdictions
without bans in every respect other than the existence of the ban. Such an
analytic approach is also an improvement over a pre/post analysis of data
from a single jurisdiction adopting the ban.
We adopted a generalized estimating equations (GEE) model for this
comparative analysis. This multivariate model allowed us to isolate the
effect of legislation while modeling annual DBIH counts adjusted for human
population counts, calendar year of DBIHs and baseline differences in
underlying DBIH rates across jurisdictions with and without legislation.
The model yielded an incidence rate ratio--i.e., the rate of DBIHs in
jurisdictions with a ban relative to the rate in jurisdictions without a
ban.
The results from the GEE model were not remarkable when data from all
Manitoba jurisdictions were analyzed, but as control jurisdictions were
more likely to be rural jurisdictions, there was a high inter-correlation
among variables. One way of controlling for the confounding effects of
rurality of jurisdictions is to stratify the dataset into rural and urban.
Therefore, we restricted analyses to urban jurisdictions alone. The
results indicated that for every one DBIH in Brandon, there were 1.29
DBIHs in Winnipeg before the pit-bull ban and 1.10 DBIHs after the ban.
This is a 14.7% reduction in rate of DBIH in people of all ages. In
people younger than 20 years old, for every one DBIH in Brandon, there
were 1.28 DBIHs in Winnipeg before the ban and 0.92 DBIHs after the ban.
This amounts to a 28.1% reduction in rate of DBIH. These findings were
statistically significant. Other reasons for this decrease cannot be ruled
out in this real-world, observational study which can be thought of as a
non-randomized, self-selected community trial. However as far as we can
ascertain, no other dog-control legislation is different between the two
jurisdictions.
Going forward, researchers should compare DBIH rates temporally as
well as geographically. Future (controlled) studies in other places where
pit-bull specific bans have been in effect long-term are still necessary
to conclusively understand if rates of DBIHs generally and gradually
decline when pit-bulls are removed from the population. This is because
effectiveness (or magnitude of rate decrease) may be variable depending on
local conditions, even if everyone agreed that pit-bulls caused a
disproportionate number of DBIHs. For example, if rate of pit-bull
penetration is high, then magnitude of effectiveness of a pit-bull ban
would likely be higher than observed in our study, if a cause-effect
relationship truly exists. However, if rate of pit-bull penetration is
zero (i.e., no pit bulls), then a ban that was proven to be 100% effective
elsewhere (hypothetically speaking) would bring about little change to
DBIH rate as, technically, there are no dogs to be banned. Furthermore,
pit bulls in one region of the world may be less aggressive than pit bulls
in another region owing to potentially different lineages and differences
in dog-owning cultures. While the value inherent in local data should not
be underestimated for the purposes of local policies, data from larger
jurisdictions with bigger populations of dogs, including those from the
banned breeds, and higher rates of DBIHs will further shed light on this
public health topic that appears to attract a lot of public and
stakeholder interest.
References
1. Raghavan M, Martens P, Chateau D, Burchill C. Effectiveness of
breed-specific legislation in decreasing the incidence of dog-bite injury
hospitalizations in people in the Canadian province of Manitoba. Injury
Prevention doi:10.1136/injuryprev-2012-040389. E-pub ahead of print.
2. Blackwell T. Controversial pit bull bans result in fewer dog
bites: study. National Post, July 5, 2012.
http://news.nationalpost.com/2012/07/05/controversial-pit-bull-bans-result
-in-fewer-dog-bites-study/ (accessed 9 September, 2012).
3. Kaufman B. Calgary bylaw boss dismisses pit bull breed ban study.
Calgary Sun. July 6, 2012. http://www.calgarysun.com/2012/07/06/calgary-
bylaw-boss-dismisses-pit-bull-breed-ban-study (accessed 9 September,
2012).
4. Kay B. Study proves pit bull ban is justified. National Post, July
6, 2012. http://fullcomment.nationalpost.com/2012/07/06/barbara-kay-
study-proves-pitbull-ban-is-justified/ (accessed 9 September, 2012).
5. DogsBite Blog. New Canadian study shows pit bull bans result in
fewer hospitalizations. Dogsbite.org, Austin, Texas. July 9, 2012.
http://blog.dogsbite.org/2012/07/new-canadian-study-shows-pit-bull-
bans.html (accessed 9 September, 2012).
6. Anonymous. Winnipeg, Manitoba far behind Calgary in community
safety. National Canine Research Council, LLC , Amenia, New York. July 9,
2012. http://www.nationalcanineresearchcouncil.com/blog/winnipeg-manitoba
-far-behind-calgary-in-community-safety/ (accessed 9 September, 2012).
7. Parsons L. Severe bites down after pit bull ban. Winnipeg Metro,
July 10, 2012. http://metronews.ca/news/winnipeg/291327/severe-dog-bites-
down-in-winnipeg-since-pit-bull-ban-study/ (accessed 9 September, 2012).
8. Jonas G. The state has no business in the dog houses of the
nation. National Post, July 11, 2012.
http://fullcomment.nationalpost.com/2012/07/11/george-jonas-the-state-has-
no-business-in-the-doghouses-of-the-nation/ (accessed 9 September, 2012).
9. Editorial: Pit bull bans may actually be working. The Hamilton
Spectator, July 11, 2012. Excerpt reprinted from The St. John's Telegram.
10. Raghavan M. Invited presentation: Study on the effectiveness of
breed-specific legislation in decreasing dog-bite injury hospitalizations
in Manitoba--what it means to researchers, policy-makers and the public.
Manitoba Agriculture, Food and Rural Initiatives (MAFRI) Lunch & Learn
Session. August 13, 2012, Winnipeg, Manitoba.
11. Ontario Ministry of the Attorney General. Information on the dog
owners' liability act and public safety related to dogs statute law
amendment act, 2005.
http://www.attorneygeneral.jus.gov.on.ca/english/about/pubs/dola-
pubsfty/dola-pubsfty.asp#TOC_03 (accessed 9 September, 2012).
12. Statistics Canada. Population, urban and rural, by province and
territory. http://www.statcan.gc.ca/tables-tableaux/sum-
som/l01/cst01/demo62a-eng.htm (accessed 9 September, 2012).
13. Statistics Canada. Focus on geography series, 2011 census--
province of Ontario. http://www12.statcan.gc.ca/census-recensement/2011/as
-sa/fogs-spg/Facts-pr-eng.cfm?Lang=Eng&GK=PR&GC=35 (accessed 9 September,
2012).
14. PRWeb. New survey reveals pet ownership at its highest level in
two decades and pet owners are willing to pay when it comes to pet's
health. American Pet Products Association Press Release, Greenwich, CT
(Vocus/PRWEb) April 04, 2011.
http://www.prweb.com/releases/2011/4/prweb8252684.htm (accessed 2Feb
2012).
15. Shepherd AJ. Results of the 2006 AVMA survey of companion animal
ownership in US pet-owning households. J Am Vet Med Assoc 2008;232:695-6.
Kerrianne Watt1, Richard C Franklin1, Belinda Wallis2, 3, Bronwyn
Griffin2, 3, Peter Leggat1; Roy Kimble2,3
1School of Public Health, Tropical Medicine and Rehabilitation
Sciences, James Cook University
2Queensland Children's Medical Research Institute
3Royal Children's Hospital, Centre for Burns and Trauma Research,
School of Medicine, University of Queensland
Re Infant Abusive Head Trauma incidence in Queensland, Australia
Kaltner et al doi:10.1136/injuryprev-2012-040331
Head trauma in children, particularly as a consequence of abuse, is an important issue and we support the need for interventions in this area. We would however like to clarify some potentially misleading information published in the article by Kaltner et al, regarding the incidence of abusive head trauma (AHT) in Queensland in relation to other serious childhood trauma such as drowning and low speed vehicle run-overs (LSVROs).
Kaltner et al estimated that the incidence rate for AHT (as defined by death or admission to hospital for greater than 24 hours) among children aged 0-2 yrs in Queensland during 2005-2008 was 6.7 per 100 000 per annum. Kaltner argued that the incidence rate for AHT was higher than that for drowning and LSVROs. However, the references used for incidence rates related to drowning and LSVROs are not comparable in several respects. Firstly, there is a 10 year gap between the incidence rates for LSVROs and drowning referenced by Kaltner et al, and the calculated AHT incidence rates. The Mackie1 data on drowning are derived from 1992-1997, and the data on LSVROs from the Queensland Council on Paediatric Morbidity and Mortality2 relate to 1994-1996. Secondly, the incidence rates for drowning and LSVROs referred to by Kaltner relate to fatalities, whereas the incidence rates calculated for AHT relate to hospital admissions and fatalities. Thirdly, Kaltner et al used data relating to 0-4 yr old children in their incidence rate calculations, whereas the referenced incidence rates for drowning and LSVRO relate to 0-5 yr olds (drowning) and 0-4yr olds (LSVRO), respectively. We suggest that for these three reasons, it is not appropriate to compare incidence rates calculated for AHT and drowning / LSVROs.
We present for alternative consideration incidence rates calculated from two recently completed studies on drowning and LSVROs funded by the Queensland Injury Prevention Council. In these studies, data from multiple sources (death, hospital admission, Emergency Department presentation, ambulance) were linked to calculate incidence rates for fatal and nonfatal drowning (2002-2008) and LSVRO incidents (1999-2009)3-4. From data collected for these two studies, we have calculated incidence rates for drowning and LSVROs using the same definitions employed by Kaltner et al for AHT (i.e., fatalities and admission to hospital for 24hrs or more), for 0-2 yr old children in Queensland, for the same time period (2005-2008). The comparable incidence rates (IR) are as follows: drowning IR = 65.27 per 100 000 per annum; LSVRO IR = 42.06 per 100 000 per annum. These incidence rates are much higher than those referenced by Kaltner et al (drowning – 4.6; LSVRO 2.4).
This information is yet to be publicly released, and highlights the value of linked data when exploring injury issues. The difficulties associated with obtaining these data may explain why Kaltner et al reported incidence rates that were not directly comparable. This also reinforces the importance of defining serious injury to allow comparison of like with like5.
There is currently no linked health dataset in Queensland. Linked data to obtain accurate, contemporary and crucial information regarding injury are only available on a project by project basis, when specific funding, ethical approval, and access approval (via the Director General of Queensland Health), are obtained. In addition, funding for the Queensland Trauma Registry was terminated, thus losing another vital source of information about injury in Queensland. As highlighted earlier this year in this journal, reliable information about injuries fundamentally underpins good injury prevention6
There is no doubt that AHT among young children is an important issue and one that deserves increased attention and focus on prevention. However this does not diminish the importance of other causes of serious and fatal injury among young children, such as drowning and LSVROs. We advocate for urgent attention on better data collection regarding serious injury in Queensland to facilitate prevention strategies for all injury among children.
References:
1. Mackie IJ. Patterns of Drowning in Australia, 1992-1997. Medical Journal of Australia; 1999; 171:587-90.
2. Queensland Council on Obstetric and Paediatric Morbidity and Mortality. Maternal, Perinatal and Paediatric Morbidity and Mortality 1994-1996. Brisbane: Queensland Council on Obstetric and Paediatric Morbidity and Mortality. Brisbane, 1998.
3. Kimble R, Wallis B, Nixon J, Watt K, Cass D, Gillen T & Griffin B. 10 Year Review of Low Speed Vehicle Run-Overs in 0-15 years across Queensland. Injury Prevention; 2010; 16 (Suppl 1): A1-289.
4. Wallis B, Watt K, Franklin R, Nixon JA, Kimble R. Nonfatal drowning in children and young people in Queensland (Australia) 2002-2008. Injury Prevention; 2010; 16 (Suppl 1): A138
5. Langley J, Cryer C. A consideration of severity is sufficient to focus our prevention efforts. Injury Prevention; 2012; 18(2) 73-74.
6. Langley JD, Davie GS, Simpson JC. Quality of hospital discharge data for injury prevention. Injury Prevention; 2007; 13: 42-44.
When Lusk et al. submit to the editor a formal list of errata to be attached to their article, I expect they will duly correct all the errors, omissions, and false statements that have been brought to their attention, and not just the three they chose to mention here. This would include amongst other items providing a correct explanation for their choices of particular termination points (rather than the non...
When Lusk et al. submit to the editor a formal list of errata to be attached to their article, I expect they will duly correct all the errors, omissions, and false statements that have been brought to their attention, and not just the three they chose to mention here. This would include amongst other items providing a correct explanation for their choices of particular termination points (rather than the nonsensical one found in footnote 2 to their Table 1), and retracting their false statement that the path and comparison streets have similar cross traffic and numbers of intersections. And as I also already objected, the authors need to explain how they got the usage data for the year 2000 they claim to have for the de Maisonneuve path segment. Considering that no municipality maintains automatic counters there, and that the authors' study was not underway in 2000, contrary to their claim it would seem they do not have data as they describe for that year.
Since I expect the authors will do their duty and correct these faults, I use the space remaining to correct two new errors they have introduced, and to object further.
(1) The path segment they claimed to have studied from 1999 to 2008 but that did not exist for almost the entirety of that period was created in 2007, not 1997.
(2) The corresponding length correction would have been approximately 180 metres, if they had gotten the extra length right to begin with. They did not, and so the correction should be instead approximately 350 metres. The authors are yet to explain how they got their lengths.
(3) The authors tell us not to worry about their selections of comparison streets: these were done "a priori, without knowledge of their safety record, in consultation with local cycling advocates". In fact the biases are so extreme that they are obvious without any measurement. Who were these sight, smell, and hearing impaired local advocates? Their contribution is not identified in either the contributorship statement or the acknowledgements, and the genesis of the study's path and comparison samples remains as mysterious as ever.
(4) The authors say their failures to describe the radical divergences between their path and comparison streets "do not affect the study results." They need to be reminded that without appropriate comparisons, their study lacks validity. Indeed, showing that a comparison is preposterous does not change the results so calculated: instead, it discredits them.
(5) I object to the authors' claim that "not even one comparison pair showed significantly greater risk" for the path. Let us be clear: even with the biased nature of the comparisons, over the near decade of the study period, according to their methods the actual injury rates on the paths were in three cases respectively 21%, 18%, and 1% worse than on the comparison streets. That none of these were found statistically significant is an indictment of the imprecision of the authors' methods, not an endorsement of the paths. I particularly object to this exploitation of the confusion between statistical and public health significance because I already called the authors on it in my previous criticism.
The authors bemoan the fact that on-street path construction has been "hampered" by the AASHTO guidelines, and present their own results as enough against them that it should no longer be discouraged. This summer a cyclist riding on the Christophe Colomb path segment studied by the authors-- a cyclist who did everything right by the rules of the path, and therefore much wrong by the ordinary rules of the road-- was killed by a truck [1] in circumstances exactly as warned about on page 34 of the AASHTO guidelines [2].
References
1. http://www.cbc.ca/news/canada/montreal/story/2012/07/24/montreal-cyclist-hit-24-07-2012.html?cmp=rss, accessed Aug 26 2012.
2. AASHTO Task Force on Geometric Design (1999). Guide for the development of bicycle facilities. Washington, DC: American Association of State Highway and Transportation Officials.
We regret the two errors that Kary identified. "What this study adds"
should read published crash [not injury] rates (the article body states it
correctly), and the Rachel length is 1.7 km [not 3.5]. In Table 1,
correcting for 1.7 doubles Rachel's absolute incident rates; however, it
raises overall crash and injury rates by only 10% to 9.6 and 11.5,
respectively. In Table 2, the relative risk comparison is unaffected sinc...
We regret the two errors that Kary identified. "What this study adds"
should read published crash [not injury] rates (the article body states it
correctly), and the Rachel length is 1.7 km [not 3.5]. In Table 1,
correcting for 1.7 doubles Rachel's absolute incident rates; however, it
raises overall crash and injury rates by only 10% to 9.6 and 11.5,
respectively. In Table 2, the relative risk comparison is unaffected since
the comparison street has the same length as Rachel. Thus, the study
conclusions remain intact.
Exclusion of the 180-m Maisonneuve extension completed in 1997 should
slightly lower its incident rates, and could not raise them by more than
10%, and would therefore not affect the overall results.
Kary's extensive criticisms focus on differences between the cycle
track and comparison streets that do not affect the study results. Readers
may be assured that all comparison segments were selected a priori,
without knowledge of their safety record, in consultation with local
cycling advocates (some of whom prefer mixed traffic over cycle tracks) as
the most similar yet realistic alternative routes. St. Denis, 10 blocks
but only 700 m from Brebeuf, was Brebeuf's comparison because, although
different in geometry, it was the main parallel alternative route for
cyclists crossing the area. Comparisons of MVO injuries demonstrate that
in the aggregate, cycle track and comparison streets revealed similar
environmental danger. Because differences are unavoidable when comparing
streets, we provide results for each comparison pair.
We welcome other studies that better control for the road
environment, including before-after studies. For now, Montreal is North
America's only long-standing, multi-route experiment with cycle tracks.
And while the comparisons in our study are not ideal case-controls, the
findings are strong, as not even one comparison pair showed significantly
greater risk for the cycle track.
1. Rue de Brebeuf Cycle Track vs. Rue St. Denis between Rachel and
Laurier.
These streets are not comparable.
Brebeuf (which has a cycle track) is a narrow 40kph slow-moving one-
way residential street with one traffic lane and one parking lane.
Rue St. Denis (which has no cycle track) is a six-lane (two lanes
often taken up by parking) 50kph limit two-way highway in a commercial
area with lot...
1. Rue de Brebeuf Cycle Track vs. Rue St. Denis between Rachel and
Laurier.
These streets are not comparable.
Brebeuf (which has a cycle track) is a narrow 40kph slow-moving one-
way residential street with one traffic lane and one parking lane.
Rue St. Denis (which has no cycle track) is a six-lane (two lanes
often taken up by parking) 50kph limit two-way highway in a commercial
area with lots of stores and distractions.
It seems to me that more accidents will naturally occur on the six-
lane highway with a faster speed limit. It's unsurprising then that the
study did indeed find a statistically significant advantage in terms of
safety for Rue de Brebeuf. However, I would argue that this has nothing to
do with the safety of the cycle track and everything to do with the very
different nature of the roads compared.
2. Rue Berri Cycle Track vs. Rue St. Denis between Cherrier and
Viger.
These streets are not comparable.
Rue Berri (which has a cycle track) is a 50kph limit divided highway
along 1/3rd of its length with the cycle track removed from busy
intersections by an underpass, so cyclists are naturally removed from the
possibility of intersection accidents.
Along this stretch of Rue St. Denis, the road (which has no cycle
track) is a one-way street with a 50kph speed limit. However it is a much
busier road than Rue Berri in terms of people doing their business
somewhere along that stretch, with a relatively narrow street and lots of
intersections and distractions in the form of little shops and cafes along
the whole route.
Rue Berri showed a statistically significant reduction in injuries
compared with its reference street. However, more accidents are bound to
occur where there are lots of intersections and where drivers are likely
to be distracted. It seems reasonable that the advantage in terms of
reduced injury results on Rue Berri derive from the very different nature
of the roads compared and not from the presence of a cycle track.
3. Boulevard de Maisonneuve Cycle Track vs. Rue Sherbrooke and Rue
Ste. Catherine between Claremont and Wood.
Boulevard de Maisonneuve (which has a cycle track) is a quiet 30kph
one-way two lane residential street along much of its length. The bike
track goes through a park for 1/5th of its length, thus removing any
possibility of intersection conflicts in that area. The presence of the
park effectively reduces the chance of traffic collisions by 20%.
Sherbrooke (which has no cycle track) is a downtown 40kph commercial
street with four lanes of moving traffic and parking on both sides. It has
numerous business distractions along its length. It should be noted that a
recent study found that Sherbrooke is the single most dangerous route in
Montreal for cyclists. Ste. Catherine (which also has no cycle track) is a
similar downtown street, but with a 30kph limit and just two lanes of
moving traffic and a lane for parking on both sides.
The idea that these streets are comparable on anything but the most
superficial level (i.e. they are streets) is a joke. It is ridiculous, in
my view, to attribute a reduction of injuries on Boulevard de Maisonneuve
to the presence of a cycle track, when the streets being compared are not
at all similar - and when the street with the cycle track has obvious and
significant advantages in terms of safety that are unrelated to the
bicycle track itself.
-----------------------
Here we have what seems to me to be a clear case of selection bias.
Note: Even though the three other street comparisons show similar
bias, the remaining street comparisons showed statistically insignificant
results.
The Results of this study are interesting, particularly comparisons
to other countries. I'd be also interested in looking into driver license
test standards. Having worked as an expat in the UK 1999-2005, I knew many
who have tried unsuccessfully to obtain a driver's license because of the
high test standards. You must pass a written test, video response test and
the road test. Only 30% successfully complete all three on t...
The Results of this study are interesting, particularly comparisons
to other countries. I'd be also interested in looking into driver license
test standards. Having worked as an expat in the UK 1999-2005, I knew many
who have tried unsuccessfully to obtain a driver's license because of the
high test standards. You must pass a written test, video response test and
the road test. Only 30% successfully complete all three on the first
attempt. I'm sure the USA pass rate is much higher. It's not unusual for
Brits to repeat the tests 3 or more times and practice intensively
between tries. Several experienced American drivers have had great
difficulty in meeting the test standards, also.
Injury Prevention asks that responses to articles be kept to less than about 300 words. The volume of errors and omissions in this article by Lusk et al. is so excessive that it took me rather more than that-- including photographs of the actual streets-- just to document them. The result is now hosted on John S. Allen's bicycle pages and can be directly found by searching the internet for e.g. these terms:...
Injury Prevention asks that responses to articles be kept to less than about 300 words. The volume of errors and omissions in this article by Lusk et al. is so excessive that it took me rather more than that-- including photographs of the actual streets-- just to document them. The result is now hosted on John S. Allen's bicycle pages and can be directly found by searching the internet for e.g. these terms: compendium errors Lusk.
A very small sample:
-Authors report results for a path section that did not exist for almost the entirety of their claimed study period.
-Errors of up to 100% in the claimed lengths of path segments, and thus corresponding errors in the reported rates of incidents per kilometre.
-Biased selection of comparison streets, such as comparing a path on a one-way, one or two traffic lane, lightly trafficked residential street having a 30 km/hr speed limit, with cycling on a two-way, 4 traffic lane numbered provincial highway having a 50 km/hr speed limit, located in a heavily trafficked commercial district, with numerous alcohol-serving establishments.
The authors went 10 blocks out of the way to find this comparison street, even though the path-adjacent streets are nearly identical in character to the path street.
-False claim of similar numbers of intersections on path and comparison streets.
-Complete reliance on an untested, illogical, ad hoc indicator of danger to cyclists (contrary to the authors' description as if it were routinely used for this purpose), one whose usefulness is refuted by the authors' own data.
-Here and elsewhere, the authors applaud bicycle paths for substantially skewing the character of the user base, from young athletic males to women, children and seniors. Thus even if the authors did their study properly and reported their results correctly-- they did not-- would their conclusion that cycle paths at least do not increase the injury rates really be an endorsement of the cycle paths, or an indictment of them?
Developing the epidemiological literature base on the occurrence of all forms of childhood injury is essential to the development and promotion of injury prevention efforts. As is rightfully highlighted by Watt, Franklin, Wall...
Hemenway (1) describes three beliefs which may jeopardize injury- avoidance: optimistic ("it will never happen to me"), fatalistic ("accidents happen") and materialistic ("you probably deserved it"). Such a scheme parallels well-known trait theories regarding the individual's general personality (2); given the value of those endeavours,Hemenway's scheme deserves serious consideration.
Nonetheless, it may be inco...
We acknowledge that we did not control for all of the differences in road geometry and building typologies because there are no ideal matched streets (Re: Cooper). However, alternative research designs also have limitation and feasibility issues. For before and after study designs, some of the Montreal cycle tracks are 20 years old, before injury surveillance and traffic counting data systems were available. Limiting to...
Our population-based study (1) on the effectiveness of breed-specific legislation (BSL) targeting pit-bull (terrier) type dogs in the Canadian province of Manitoba generated some interest in the media and among policy -makers and the public in Canada and the United States (2-10). With this experience of listening to different stakeholders and communicating with some, we hope to elaborate on our findings in language that is...
Kerrianne Watt1, Richard C Franklin1, Belinda Wallis2, 3, Bronwyn Griffin2, 3, Peter Leggat1; Roy Kimble2,3
1School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University
2Queensland Children's Medical Research Institute
3Royal Children's Hospital, Centre for Burns and Trauma Research, School of Medicine, University of Queensland
Re Infant Abusive H...
When Lusk et al. submit to the editor a formal list of errata to be attached to their article, I expect they will duly correct all the errors, omissions, and false statements that have been brought to their attention, and not just the three they chose to mention here. This would include amongst other items providing a correct explanation for their choices of particular termination points (rather than the non...
We regret the two errors that Kary identified. "What this study adds" should read published crash [not injury] rates (the article body states it correctly), and the Rachel length is 1.7 km [not 3.5]. In Table 1, correcting for 1.7 doubles Rachel's absolute incident rates; however, it raises overall crash and injury rates by only 10% to 9.6 and 11.5, respectively. In Table 2, the relative risk comparison is unaffected sinc...
1. Rue de Brebeuf Cycle Track vs. Rue St. Denis between Rachel and Laurier.
These streets are not comparable.
Brebeuf (which has a cycle track) is a narrow 40kph slow-moving one- way residential street with one traffic lane and one parking lane.
Rue St. Denis (which has no cycle track) is a six-lane (two lanes often taken up by parking) 50kph limit two-way highway in a commercial area with lot...
The Results of this study are interesting, particularly comparisons to other countries. I'd be also interested in looking into driver license test standards. Having worked as an expat in the UK 1999-2005, I knew many who have tried unsuccessfully to obtain a driver's license because of the high test standards. You must pass a written test, video response test and the road test. Only 30% successfully complete all three on t...
Injury Prevention asks that responses to articles be kept to less than about 300 words. The volume of errors and omissions in this article by Lusk et al. is so excessive that it took me rather more than that-- including photographs of the actual streets-- just to document them. The result is now hosted on John S. Allen's bicycle pages and can be directly found by searching the internet for e.g. these terms:...
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