Cycle helmets: A summary of research

If you know of other research, please contact John Franklin.

References are listed by order of date, then title.

Summaries of papers marked * are based on third-party information and have not been verified by John Franklin, who is also not responsible for the content of links to third-party sources provided for reference.

Do bicycle safety helmets reduce severity of head injury in real crashes? *

Dorsch et al. Accident Analysis and Prevention Vol 19:3 pp183-90, 1987.

Predicts 90% saving in fatalities through use of hard-shell helmets.

Reducing bicycle accidents: a re-evaluation of the impacts of the CPSC bicycle standard and helmet use *

Rodgers. Journal of Product Liability 11 pp307-17, 1988

To examine claims that growth in the use of hard shell cycle helmets had been successful in reducing cycle-related injuries and death, Rodgers studied over 8 million cases of injury and death to cyclists in the USA over 15 years. He concluded: "There is no evidence that hard shell helmets have reduced the head injury and fatality rates. The most surprising finding is that the bicycle-related fatality rate is positively and significantly correlated with increased helmet use".

A case-control study of the effectiveness of bicycle safety helmets

Thompson RS, Rivara, Thompson DC. The New England Journal of Medicine Vol 320:21 pp1361-7, 1989.

A study conducted at five hospitals in Seattle between December 1986 and December 1987 of cyclists admitted to an emergency room. Of 776 cyclists admitted, 269 had head injuries. 235 of these, and 433 of the 507 cyclists who were admitted without head injuries, completed a questionnaire. The study concluded that cycle helmets reduce the risk of head injury by 85% and of brain injury by 88%. [j264]
Criticisms of this paper

Helmet protection from head injuries among recreational bicyclists *

Wasserman et al. American Journal of Sports Medicine Vol 18:1 pp 96-7, 1990.

Predicts helmets would reduce concussions by 29%, skull fractures by 82%.

Land transport fatal accident report *

Land Safety Transport Authority, New Zealand. 3 reports: 1989, 1990, 1991.
Referenced from: The cost-effectiveness of compulsory bicycle helmets in New Zealand.

Of 42 cyclists over 3 years not wearing helmets who were killed (all causes, not just head injuries), 6 may have survived if they had been wearing a helmet. For 21 of the cyclists a helmet would probably have made no difference.

A prospective analysis of injury severity among helmeted and non-helmeted bicyclists involved in collisions with motor vehicles *

Spaite et al. Journal of Trauma Vol 31:11 pp1510-6, 1991.

Helmet non-use in this study is strongly associated with severe injuries. However, this is true even when cyclists without major head injuries are analysed as a group. The implication is that people who do not use helmets tend to be in higher impact collisions that helmet users, since the injuries suffered in body areas other than the head also tend to be more severe.

Evaluation of the bicycle helmet wearing law in Victoria during its first 12 months

Cameron, Heiman, Neiger. Monash University Accident Research Centre Report 32, 1992.
Abstract available on-line

see: Evaluation of the bicycle helmet wearing law in Victoria during its furst four years.

Cycle helmets: the case for and against

Hillman. Policy Studies Institute ISBN 0 85374 602 8, 1993
Contents and short summary available on-line

32-page analysis of pros and cons of cycle helmets with extensive references. Wearing a helmet only marginally reduces the extent of head injury following collision with a motor vehicle, but can affect behaviour so that wearers cycle less cautiously. Mandatory helmets would reinforce public perceptions that cycling is dangerous and encourage the view that cyclists are responsible for their own injury. Life years gained through cycling outweigh life years lost in cycling fatalities by a factor of 20:1. Encouraging helmets leads to fewer people cycling and a net health loss. [j511]

Head injury reductions in Victoria two years after introduction of mandatory bicycle helmet use

Finch, Newstead, Cameron, Vulcan. Monash University Accident Research Centre Report 51, 1993.

see: Evaluation of the bicycle helmet wearing law in Victoria during its furst four years.

The effectiveness of bicyclist helmets: a study of 1,710 casualties *

McDermott et al. Journal of Trauma Vol 11:6 pp834-45, 1993.

Study copying techniques of Thompson 1989 research but yielding less favourable results. Own data suggests helmets give 25% reduction in risk of head injury for adults, but no reduction for serious injuries. Adjusting Thompson results to eliminate forehead lacerations, re-calculated benefit is 61% (instead of 85%). Also noted small sample size in Thompson data.

Bicyclist head injuries in Victoria three years after the introduction of mandatory helmet use

Newstead, Cameron, Gantzer, Finch. Monash University Accident Research Centre Report 75, 1994.
Abstract available on-line

see: Evaluation of the bicycle helmet wearing law in Victoria during its furst four years

Effectiveness of bicycle helmets in preventing head injury in children *

Thomas et al. British Medical Journal Vol 308 pp173-6, 1994.

Potential of 63% reduction in all head injuries to children under 14 years.

Injury patterns in cyclists attending an accident and emergency department: a comparison of helmet wearers and non-wearers

Maimaris, Summers, Browning, Palmer. British Medical Journal Vol 308 pp 1537-40, 1994.

One-year (1992) study at Addenbrooke's hospital based on 1,040 cycle casualties, 114 of whom had worn helmets. No difference between helmet wearers and non-wearers with respect to type of accident and nature of non-head injuries. Head injury sustained by 4% of helmet wearers against 11% of non-wearers. 18% of accidents with motor vehicles involved head injury; 7% when no motor vehicle involved. Deduced increased risk factor of 2.95 if motor vehicle involved, and 3.25 protection factor for wearing a helmet. Advocates compulsory use of helmets. [j986]

Evaluation of the bicycle helmet law in Victoria during its first four years

Carr, Skalova, Cameron. Monash University Accident Research Centre Report 76, 1995.
Abstract available on-line

Together with Evaluation of the bicycle helmet wearing law in Victoria during its first 12 months, Head injury reductions in Victoria two years after introduction of mandatory bicycle helmet use, and Bicyclist head injuries in Victoria three years after the introduction of mandatry helmet use, comprises a year-on-year evaluation of head injuries following the introduction of the Victoria helmet law.

Hospital data did not show relationship between helmet wearing and head injury in immediate pre-law years for crashes not involving a motor vehicle. However, head injury rates for cyclists in these crashes were significantly lower post-law. A significant inverse relationship between helmet use and head injury was found for cyclists involved in crashes with motor vehicles. Accident claims showed head injury rates significantly below pre-law predictions in second post-law year, but benefit appeared to have been lost in third year. Hospital records failed to show any additional benefit of law over pre-law trends in the 3 post-law years.

1995 report found biases in injury data used in previous reports, affecting analysis and results, and suggested that hospital admissions for head injury in first 4 years was 40% below pre-law trends and that severity of injuries had declined.

Report abstracts make no reference to trends in the number of people cycling or relative risk.

The cost-effectiveness of compulsory bicycle helmets in New Zealand

Hansen, Scuffham. Australian Journal of Public Health Vol 19:5 pp450-4, 1995

Efficacy of helmets in protecting cyclists in New Zealand may be considerably less than predicted by other studies.Cost of helmets per life saved varies from $88,379 for primary school children to $1,014,850 for adults. By comparison, avoided hospital costs range from $3,304 to $56,035. [j984]

The effectiveness of bicycle helmets: a review

Henderson. Motor Accidents Authority of New South Wales, 1995.

Bicycle helmets substantially reduce risk of head injury in a crash. Cyclists deaths in Australia have fallen by one half in ten years, most in the years since 1989 (mandatory helmet laws were introduced 1990 to 1992). In Victoria head injuries decreased 48% and 70% in two years after law. In Queensland cyclist head injuries fell by more than half following the law, whilst other bicycle-related injuries remained the same. Old-style (not Standards approved) helmets ineffective. All helmets less effective if wrongly placed or without straps tightened. [j997]
Criticisms of this paper

Bicycle helmets – are they up to standard?

Pedder. Injury Prevention Vol 2:4 pp250-251, 1996

Helmets must be fitted and worn properly to be fully effective. Even if used properly, a helmet certified to a recognised standard has limited protective capabilities. The design of current helmets reflects the minimum performance requirements of helmet standards, so that it is often inadequate in several respects. Modern helmets protect too small an area of the head. They are not tested for the ability to reduce rotational acceleration. They sometimes fail to provide optimal protection against the more common lesser impacts because they are tested only against severe impacts. Straps and buckles are often not strong enough. Shapes are designed for the heads of adults, not children. Mandatory helmet legislation should only be with reference to adequate helmet standards. [j1002s]

Cycle helmet laws - facts, figures and consequences

Robinson D. Paper presented at Velo Australis, 1996.
Full paper available on-line [j987]

Similar content to author's Head injuries and bicycle helmet laws.

Cycle helmets - when is legislation justified? *

Unwin. Journal of Medical Ethics Vol22 pp41-5, 1996.

Aim of paper is not to argue for or against compulsory helmets, but to suggest criteria on which the debate should focus. Author provides four criteria that should be met before legislation:

Circumstances and severity of bicycle injuries

Thompson DC, Rivara, Thompson RS. 1996
Full paper available on-line

Summary report of the Harborview Helmet Studies.
Study at 7 Seattle hospitals involving 3,390 cyclists who were injured or died 1992-4. Individuals with head or brain injuries compared to those involved in crashes but who did not suffere such injuries. 50.6% had worn helmets at time of crash. Concluded that helmets decrease risk of head injury by 69%, brain injury by 65% and severe brain injury by 74%. Helmets work equally well for all age groups, and in crashes with and without motor vehicles (which are most important risk factor for serious injury). Substantial protection provided against lacerations and fractures to upper and mid-face, but not to lower face. Hard shell helmets may offer greatest protection against severe brain injury. [j977]

Head injuries and bicycle helmet laws

Robinson DL. Accident Analysis and Prevention Vol 28 No 4 pp463-75, 1996.
Abstract available on-line

Review of mandatory helmet laws in Australia. Greatest effect of law was to discourage cycling. Increase to at least 75% helmet wearing resulted in decline of only 13% in head injuries, less than decline in cycling. Reduction in head injuries very similar for pedestrians, and possibly due more to speed and drink-driving initiatives than helmets. Helmets for motor vehicle occupants have potential to save 17 times as many deaths as cyclists, without adverse effects of discouraging a heathy mode of transport. [j982]

Is there any reliable evidence that Australian helmet legislation works?

Bruce Robinson, Bicycle Federation of Australia. Velo Australis conference, 1996.
Full paper available on-line

The author is a long-time advocate of cycle helmets and did not oppose Australian legislation. The evidence so far indicates that our initial belief in the effectiveness of the legislation may well have been ill-founded, and our hopes for road safety and equity improvements as a result of the Federal funding package naive. So far there is no convincing evidence that Australian helmet legislation has reduced the risk of head injury in bicycle crashes. It is not clear why the legislation has not been more effective. [j993]

The pattern of injury in fatal pedal cycle accidents and the possible benefits of cycle helmets

Kennedy. British Journal of Sports Medicine Vol 30 pp130-3, 1996.

Examination of 28 cyclists deaths over 15 years in Sheffield and Barnsley. Over 80% of both cases and controls had severe head injuries, but controls (an equal number of pedestrians and motor vehicle occupant fatalities) suffered more fatal injuries to other parts of the body. If helmets had saved all those who only had head injuries, at best 14 (50%) of cyclist deaths would have been prevented. On the other hand, if pedestrians and vehicle occupants had worn helmets, 175 lives may have been saved in the same period. No justification for compelling cyclists to wear helmets without taking steps to improve safety of all road users. [j983]

Trends in cycle injury in New Zealand under voluntary helmet use

Scuffham, Langley. Accident Analysis and Prevention, Vol 29:1, 1997
Abstract available on-line

An ecological analysis of serious head and non-head injuries to cyclists, and helmet wearing survey data, 1989 to 1992 (prior to introduction of NZ manadatory helmet law). Helmet wearing rates increased over period from 46% to 84% for primary schoolchildren, 23% to 62% for secondary schoolchildren, and 21% to 39% for adults. All serious injuries to cyclists decreased substantially for children, but not for adults. Serious head injuries as a percentage of all serious injuries remained constant for all groups, with no apparent difference between bicycle-only and motor vehicle related crashes. However, percentages of mild concussions and lacerations to the scalp decreased more than other cyclist head injuries. The failure to achieve the expected decline in serious head injury could be attributable to a variety of factors, including the incorrect fitting and wearing of the helmet. Cycle use declined over the study period by 19%. [j985s]

Get a head start

Which?, journal of The Consumers' Association, pp 28 - 31, October 1998.

Performance tests of cycle helmets, all produced to meet international standards. 14 of the 24 helmets failed the test criteria for shock absorption, and two of the remainder failed tests related to retention and strap strength. Only two of the 24 helmets met the more demanding Snell standard, and one of those caused some impairment of a cyclist's vision. [j980]

Helmet laws and health

Robinson. Injury Prevention, pp 170-172, September 1998.
Also Australian Doctor, 27 February 1998.
Available on line

Uses data from Australia to suggest that cycle helmet laws have done more harm than good. They have not produced any noticeable reduction in head injury rates. However, by discouraging cycling, they have deprived many of healthy exercise and pollution-free transport. [j1023]

Prevention of head injuries to car occupants: an investigation of interior padding options

McLean et al, Federal Office of Road Safety Australia, Report CR160, 1998
Summary on line

Head injuries to car occupants are a major cause of death and permanent brain damage. Evaluates benefits for motorists of interior padding and the use of headwear, such as a soft shell bicycle helmet. It is concluded that helmets would offer by far the best form of protection, with or without car air bags. Total benefits are estimated to be AUD380 million, compared with AUD123 million for car padding.

Latest CPSC helmet standard and US fatality trends

Kunich, 1998
Available on line

Comments on shortcomings of helmet standards, and analyses US cyclist and pedestrian fatalities from 1986 to 1996. During this period cycle helmet use grew from close to zero to 30% or more. There is no reflection of this in the fatality statistics; indeed cyclist deaths have declined less rapidly than those of pedestrians. [j979]

Cyclist fatalities in Canada 1975 to 1997

Burdett, 1999
Available on line

Fatality trends have been similar for cyclists and pedestrians over 22 years of study; both have fallen. Although helmet use grew from virtually zero in 1988 to over 30% in 1995 and up to 50% in 1997, there is no detectable change in the fatality trends attributable to this. Programs aimed at motorists have been effective at reducing fatalities to all road users, including pedestrians and cyclists. Measures are needed to improve cyclists' skills and to increase use of lights by cyclists at night. [j994]

An Economic Evaluation of the Mandatory Bicycle Helmet Legislation in Western Australia

Hendrie, Legge, Rosman & Kirov, Road Accident Prevention Research Unit, WA, 1999
Available on line

Acknowledges criticisms of earlier studies of effectiveness of helmet legislation. Makes new assessment of head injury reduction by two methods, taking into account trends affecting all road users. These give absolute reductions in head injuries of 20% and 11% respectively, less than the decrease in cycle use. Also assesses cost effectiveness of the legislation. Depending upon assumed level of injury reduction, cost benefit is +$AUS 2m to - $AUS 10.6m. Many costs excluded, included those associated with reduced cycling activity.[j]

Cycle helmets

Report by the Board of Science and Education, British Medical Association, June 1999.
ISBN 0 7279 1430 8

Looks at cycling crashes and injuries in the UK; cycle helmet design, standards and benefits; health benefits of cycling; international evidence from countries where cycle helmets are compulsory; and makes recommendations for BMA policy.

The report recognises the limitations of helmets and research, and the negative health effects of discouraging people from cycling through helmet promotion. It would be of concern to the BMA if people stopped cycling or transferred more to cars. Notes that helmet legislation would only cover on-highway cycling where helmet benefits are least, and not off-road where they may have a more useful role to play.

Recommends against the compulsory use of helmets and in favour of promotion. Helmets should be only one part of a much broader strategy to promote cycling.

Estudio sobre accidentes de ciclistas en carretera

Ministerio del Interior, Spain, March 1999
PDF file

Spanish Government investigation of non-fatal cycle accidents on road, which concludes that no advantages of helmet wearing have been found in the data set.

Trends in cyclist casualties in Britain with increasing cycle helmet use

Franklin, 2000
Available on line

Examines cyclist casualties in Britain as a whole, Greater London and Cambridge, over the period when helmet use has risen from virtually zero to over 40 per cent of cyclists in some parts of the country. There is no detectable change in trends for fatalities, serious injuries or severity ratio in any of these data sets to match the increase in use of cycle helmets. Indeed, in some cases the average seriousness of cyclist casualties increased duirng the period of greatest helmet take-up.

The paper also looks at findings from research in the USA, Canada, Australia and New Zealand that have also failed to find real-world evidence of any significant reduction in cyclist head injuries in large population samples. [j]

Helmets for preventing head and facial injuries in bicyclists

Thompson DC, Rivara, Thompson R, The Cochrane Library, issue 3, 2000, Oxford.

Analysis of five studies into head injury (including two by the review authors) and three into facial injury (including two by review authors), considered to be best to meet selection criteria. Considers these provide clear evidence that helmets reduce head and facial injuries for cyclists of all ages in all types of crashes.

Head injuries to bicyclists and the New Zealand Bicycle Helmet Law

Scuffham, Alsop, Cryer & Langley, University of Otago, 2000

Examined injuries to three age groups of cyclists admitted to hospitals in New Zealand between 1988 and 1996. Results indicate a positive effect of helmet wearing on head injury, which was relatively consistent acorss age groups and injury types. Admits results inconsistent with research by Scuffham and Langley in 1997 but offers no clear explanation for this.

Trends in serious head injuries among cyclists in England: analysis of routinely collected data

Cook, Sheikh, BMJ 28th October 2000
Available on line

For 4 years from 1 April 1991, using NHS records of emergency admissions, calculated number of cyclists admitted with head injuries as percentage of total number of cyclists admitted, subdivided into 3 age ranges. Total emergency admissions changed little over period, but number with head injuries fell from 3393 to 2571. As helmet use had risen over this period, concludes that decrease in head injuries due to increased helmet use.

This article has been much criticised for being over-simplistic and not considering any other possible influences or long-term trends. Calculation in results in error by a factor of 10. Many criticisms are referenced from the article on the BMJ website.

Bicycle helmet efficacy: a meta-analysis

Attewell, Glase & McFadden, Accident Analysis and Prevention, 2001 pp 345-352

Analysis of peer-reviewed studies which include individual injury and helmet use data, published 1987-98. Overall risk reduction 45% for head injury, 33% for brain injury, 27% for facial injury, 29% for fatal injury. Some evidence of increased neck injury. Authors plead for greater acceptance of helmet use.

Comment: Most studies used have very small samples, sometimes only 3 to 10 injured cyclists. Largest sample is 757.

A bicycling mystery: head injuries piling up

Barnes, 2001
Report in New York Times, 29th July 2001

According to data from the US Consumer Product Safety Commission, the number of head injuries to cyclists has increased 10 per cent since 1991 despite a sharp rise in cycle helmet use. But ridership over the same period has declined, so that the rate of head injuries per active cyclist over the decade has increased 51 per cent.

Experts are mystified as to why injuries are on the rise. According to CPSC assistant executive director Ronald L. Medford, "It's puzzling to me that we can't find the benefit of bike helmets here".

The article floats several possible reasons for the discrepancy, such as an increase in aggressive driving, the improper wearing of helmets and a shift to off-road riding, but emphasises most the possibility of risk compensation. Almost no-one, says the article, suggests that cyclists should stop wearing helmets, accepting the unsubstantiated Thompson, Rivara & Thompson statistic that helmets reduce the severity of brain injuries by 88 per cent.

Effect of legislation on the use of bicycle helmets

LeBlanc, Beattie, Culligan. Canadian Medical Association Journal, 5th March 2002.

Also: Hats off (or not?) to helmet legislation
Chipman. In same issue of Journal.

Main article on-line
Supplementary article.

In 1997 legislation made the use of helmets mandatory for cyclists in Nova Scotia. In 3 years the proportion of cyclists wearing helmets rose from 36% to 86% and the proportion of head injuries to cyclists halved. However, there was also a drop of 40% to 60% in the number of people who cycle, with the greatest decrease amongst adolescents. In the context of reduced cycle use, those who continue to cycle but now wear helmets are no less likely to suffer a head injury than before. The number of head injuries has fallen only in line with cycle use.

However, the number of non-head injuries to cyclists over the 3 years increased by 6% in absolute terms. Relative to cycle use, those who continue to cycle are now 87% more likely to suffer injury than prior to helmet legislation.

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