Critique of BMA paper

Hot off the modem:

http://www.cyclehelmets.org/mf.html#1101

Legislation for the compulsory wearing of cycle helmets
================================================== =====

Board of Science and Education, British Medical Association, November
2004

Summary
=======
In response to correspondence from a number of its members, the BMA
has reconsidered its policy on this issue. Previous policy attached
significant emphasis on the BMA's wish not to discourage cycling by
making helmets compulsory.

BMA cites evidence that it believes shows that helmet legislation no
longer leads to less cycling, and that helmets have proven effective
in protecting against head, brain, severe brain and facial injuries,
as well as death, as a result of cycling accidents. It therefore
believes that the BMA should support the introduction of legislation
making the wearing of helmets compulsory for both children and adults.
It is important that legislation should be enforced and complemented
by educational and promotional campaigns. Other measures, such as
cycle training and the creation of a safer cycling environment, should
also be pursued.

Comment
=======
The BMA paper is not a comprehensive or balanced review of evidence.
Its references have been accepted at face value even when the subject
of published criticism or contradictory evidence. Some of the facts on
which the paper relies are simply wrong.

Legislation as a deterrent to cycle use
---------------------------------------
The BMA states that evidence from Australia that helmet laws
discourage cycling is outdated, "and contains distortions from
variables including a reduction in the legal age of driving that meant
more teenagers travelled in motor vehicles".

The driving age was lowered, from 18 to 17, only in the state of
Victoria, where pre-law 17-year olds accounted for 6% of cycle traffic
[1]. Even if every 17-year old cyclist had changed completely to
driving, that would account for only a small part of the 43% drop in
cycling by Victorian teenagers post-law. It would not account at all
for the decline of up to 60% in cycling among teenagers elsewhere in
Australia.

Evidence from Australia indicates that its helmet laws continue to
deter cycle use and that in most parts of the country cycling levels
are still well below pre-law levels. Where cycling levels have
recovered, there has been the loss of more than a decade of cycling
growth (cycling levels were generally increasing pre-law), and in some
places part of the new increase is due to population growth.
Furthermore there have been shifts from regular utility cycling (which
yields the greatest health benefits) to leisure cycling, and in the
average age of cyclists, with considerably fewer children now riding
[2].

In the Australian state of Northern Territory, the mandatory helmet
law has been partially repealed, leading to wearing rates of only 15 -
20% today. Yet this state now has the highest proportion of people who
cycle in Australia and the lowest ratio of cyclist hospital admissions
to population. [3]

In other countries, too, there is clear evidence that helmet laws have
a large and long-lasting effect on cycle use. In New Zealand, cycling
by schoolchildren remains 40% lower than before the helmet law [4]. In
Nova Scotia, Canada, cycle use fell by 40% to 60% following the
introduction of a helmet law, with the largest decrease among
teenagers [5].

The BMA bases its claim that helmet legislation does not reduce the
numbers of children cycling on a single report [6] based solely on
Ontario, Canada. However, as that report acknowledges, the helmet law
in Ontario was not enforced, which could explain why the number of
child cyclists did not reduce [7]. Yet the BMA is seeking strong
enforcement of new helmet laws. The Ontario report has also been
criticised for its limitations; for example it was based on a small
sample size and did not consider cycle use by older children who are
the most likely to give up cycling [8].

Helmet use
----------
The BMA says that cycle helmet use is rising, from 16% in 1994 to 25%
in 2002, suggesting that it would now be more acceptable to introduce
a helmet law. However, these rates only reflect use by adults on main
roads. Helmet use by children declined over the same period from 17.5%
to 15.2% (16.0% to 12.3% for boys who are 5 times more at risk than
girls), indicating that children still have no desire to wear helmets.
On minor roads, where most cycling takes place, wearing rates were
10.9% for adults, 6.5% for children in 2002 [9].

The scale of the 'problem'
--------------------------
According to the BMA, each year over 50 people aged 15 years and under
are killed by cycling accidents, of whom 70 to 80 per cent die from
traumatic brain injury.

These statistics are grossly in error. In 2002, 19 children were
killed in cycling accidents in England, of whom 10 died as a result of
head injuries [10]. In Scotland the same year, no child cyclist died
of head injury [11]. Hospital data for England shows that in 2002-3
there were just over 2,000 admissions for head injury to children when
cycling. Of these, no more than a few hundred (max 516) were serious
injuries with the potential for mitigation by cycle helmets. This is
in the context of 6 million children who cycle in England. [12]

The BMA repeats speculation that there are 90,000 cycling accidents
each year on-road, and 100,000 off-road. There is no scientific basis
to assert such figures and they are not relevant to the paper. The
vast majority of injuries to cyclists do not involve head injury and
usually amount to no more than cuts or bruises.

The evidence
------------
The BMA says that studies in a number of countries have shown that
high usage rates of helmets as a result of legislation is associated
with a reduction in cycle related deaths and head injuries.

However, large-population studies have not shown a beneficial link
between helmet use and fatalities. The largest ever survey, of over 8
million cases of injury and death to cyclists in the USA over 15
years, concluded that there was no evidence that helmets had reduced
head injury or fatality rates [13]; indeed, it suggested that helmeted
riders were more likely to be killed. Other studies from the USA [14]
and Canada [15] based on whole populations have also found no effect
on fatalities.

In New South Wales (Australia) in the 3 years following the enactment
of its helmet law, 80% of cyclists killed and 80% of those seriously
injured had worn helmets. These proportions were almost identical to
helmet wearing rates at the time [16] [17] [18]. More recent reports
from Australia suggest that increases in helmet wearing have had
little, if any, positive impact on head injuries [19] [20]. A similar
situation has been reported in New Zealand [21].

Outside the context of helmet laws, increasing helmet use does not
appear to have influenced fatal or serious injury trends in Great
Britain [22] or Germany [23]. In the USA, helmet use increased from
18% to 50% of cyclists from 1991 to 2001 whilst the absolute number of
head injuries went up 10%. Pro-rata cycle use, cyclists in 2001 were
more likely to suffer a head injury than a decade earlier [24].

One paper cited by the BMA [25] has been criticised for presenting
insufficient information by which to assess the validity of its
methodology [26]. It was funded by the Snell Foundation, whose income
is derived in part from helmet sales, and the benefits predicted are
not supported by any large population evidence. The Cochrane Review
[27] was written by the same authors and has been criticised for its
lack of impartiality. 4 of the 7 papers reviewed - representing more
than three-quarters of the cyclists studied - are by the authors
themselves and dominate the analysis. The papers suggesting the
greatest protective effects for helmets have been widely criticised
for comparing quite different groups of cyclists. Much of this
criticism has been appended to the Review in the form of criticism and
contrary evidence, but this seems not to have been taken into account
by the BMA.

The BMA cites a New Zealand study that demonstrated a 19 per cent
reduction in head injuries to cyclists following legislation. However,
further analysis of the original data for this report showed that the
reduction in head injuries after the law was the returning to normal
of cyclist injury trends that had risen immediately before the law,
during rising helmet use. Taken across the full pre/post law period,
there was no improvement in head injuries to cyclists greater than
that enjoyed by the population as a whole [28] [21]. The New Zealand
Household Travel Survey shows that cycling hours decreased by 34% from
1989 to 1997, or approximately 22% following the helmet law. This
cancels out the 19% reduction in head injuries suggested by Scuffham
et al [29].

Reference to a decrease in head injuries in Victoria, Australia is
misleading, as is the source cited. A problem is that other
legislation relating to speeding and drink-driving was introduced
around the same time as the state's helmet law. A consequence of this
is that pedestrian fatalities fell by 45% in the year following the
laws, although this clearly had nothing to do with the helmet law.
Cyclists, too, would have benefited from the other laws, so it is not
possible to determine any benefit from the helmet law in isolation.
However, the helmet law did result in a fall of 44% in cycling by
teenagers and a fall of 29% in cycling by adults, which in itself
would account for most of the 40% fall in cyclist head injuries. Some
researchers have concluded that cyclists were more likely to suffer
head injuries as a result of the helmet law [30].

Enforcement
-----------
The BMA refers to an education programme in Reading [31] that resulted
in an increase in helmet use and a concurrent decrease in
cycling-related injuries. This paper has been criticised for its poor
methodology. Helmet use was judged by self-reporting alone, with no
independent verification. The intervention town and the control town
(Basingstoke) were quite different in character and the nature of
cycling in the two towns would have been different. There was no
monitoring of cycle use against which to compare decreases in
injuries.

The conclusion of the Reading report, that an increase from 11% to 31%
in the proportion of children wearing helmets led to a 45% reduction
in head injuries, is implausible even if helmets were 100% effective.
Correlation of this report with an earlier report [32], suggests that
at least part of the decrease in head injuries occurred before the
increase in helmet wearing. Road casualty data for the Reading area
shows no benefit for child cycling casualties; indeed, there is a peak
in the (very small) number of serious injuries towards the end of the
research period.

References
----------
[1] Day to day travel in Australia 1985-6. Federal Department of Road
Safety, 1989.
[2] The West Australia. 10th March 2004.
[3] Australia Cycling: Bicycle ownership, use and demographics. Draft
report, 2004.
[4] New Zealand Travel Survey 2004, Land Transport Safety Authority.
[5] Hats off (or not?) to helmet legislation, Chipman R. Canadian
Medical Association Journal 2002, 166(5).
[6] Mandatory helmet legislation and children's exposure to cycling,
Macpherson AK et al. Inj Prev 2001;7(3):228-230
[7] Butting heads over bicycle helmets, Avery AJ, CMAJ,
www.cmaj.ca/cgi/eletters/167/4/338
[8] Helmet laws and cycle use, Robinson DL. Injury Prevention
2003;9:380–383.
[9] Cycle helmet wearing in 2002, Gregory K, Inwood C, Sexton B.
Transport Research Laboratory Report 578, 2003.
[10] Parliamentary Question by Brian Jenkins MP, answered by Dr
Ladyman, Department of Health. Hansard Written Answers, 10th November
2003.
[11] Data from General Register Office, Scotland.
[12] Analysis of hospital admissions data for England 1995/6 - 2002/3.
Awaiting publication.
[13] Reducing Bicycle Accidents: A re-evaluation of the impacts of the
CPSC bicycle standard and helmet use, Rodgers. Journal of Product
Liability, Vol 11 pp 307-317, 1988.
[14] Latest CPSC helmet standard and US fatality trends, Kunich, 2002.
[15] Cyclist fatalities in Canada 1975 to 2002, Burdett, 2003.
[16] Head injuries and bicycle helmet laws. Robinson DL. Accident
Analysis and Prevention, 1996 Jul;28(4):463-7.
[17] Road Traffic Accidents in New South Wales, 1992, 1993, 1994.
Roads and Traffic Authority of New South Wales.
[18] An observational study of law compliance and helmet wearing by
bicyclists in New South Wales 1993. Smith NC, Milthorpe FW. Roads and
Traffic Authority NSW, 1993.
[19] Head injuries and bicycle helmet laws, Robinson DL, Accident
Analysis & Prevention, 1996 Jul;28(4):463-75
[20] An Economic Evaluation of the Mandatory Bicycle Helmet
Legislation in Western Australia. Hendrie D, Legge M, Rosman D, Kirov
C. 1999. Road Accident Prevention Research Unit, University of Western
Australia
[21] Changes in head injury with the New Zealand bicycle helmet law.
Robinson DL. 2001. Accident Analysis & Prevention: 2001
Sep;33(5):687-91
[22] Trends in cyclist casualties in Britain with increasing cycle
helmet use. Franklin JA, 2000.
[23] Specific patterns of bicycle accident injuries - An analysis of
correlation between level of head trauma and trauma mechanism. Möllman
FT, Rieger B, Wassmann H. DGNC Köln, 2004.
[24] Data from Consumer Product Safety Commission. Report in New York
Times, 29th July 2001.
[25] Circumstances and severity of bicycle injuries, Thompson DC,
Rivara FP, Thompson RS. 1996. Snell Memorial Foundation.
[26] Bicycle helmets - a review of their effectiveness. Department for
Transport Road Safety Research Report No 30, 2002.
[27] Helmets for preventing head and facial injuries in bicyclists,
Thompson et al. Cochrane Database Syst Rev. 2000;2:CD001855
[28] The bicycle helmet legislation, curse or cure?, Perry N.
University of Canterbury, 2001.
[29] Land Transport Safety Authority.
ww.ltsa.govt.nz/research/travel_survey/research/travel_survey.html
[30] Helmet laws, numbers of cyclists and accident rates, Robinson DL.
[31] A hospital led promotion campaign aimed to increase bicycle
helmet wearing among children aged 11-15 living in West Berkshire
1992-1998, Lee et al. Injury Prevention 2000, 6:151-153.
[32] A bicycle helmet promotion campaign for the under 16 year olds in
West Berkshire, England 1992-1995, Lee & Smyth. Pro Velo Australis
International Bicycle Conference, Freemantle, Western Australia, 1996.



Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

Just zis Guy, you know? wrote:
Hot off the modem:

http://www.cyclehelmets.org/mf.html#1101

Legislation for the compulsory wearing of cycle helmets
================================================== =====


Excellent critique - just needs a few references filling in e.g. 14, 15
have no reference to where they were published.

Otherwise can we get the CTC to send a personal copy to every member of
the Science & Education Board. Helen, can you, as a member get hold of
a list of the Board members?

Tony

On 11 Nov 2004 10:19:11 -0800, "Tony Raven"
wrote in message
.com:

Excellent critique - just needs a few references filling in e.g. 14, 15
have no reference to where they were published.

Still a bit of a work in progress, but the cabal (TINC) are honing it
as we speak.

Otherwise can we get the CTC to send a personal copy to every member of
the Science & Education Board. Helen, can you, as a member get hold of
a list of the Board members?

Without wishing to make any suggestion which could be construed as
implying anything regarding membership of the cabal (TINC), or indeed
the secret society which is behind the site, I think it is safe to say
we have that angle covered :-)

This could be read as implying that I am in some way connected with
cyclehelmets.org. This would be entirely correct.

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University