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A research paper in todays BMJ states that cycle helmets are of benefit both to children and, contrary to popular belief, to adults.
The reason that people most frequently cite for not cycling, says the paper, is risk of injury.
Measures to increase cycle use must therefore address safety. Local publicity campaigns encouraging the voluntary wearing of helmets have been effective and should accompany national drives to promote cycling.
An editorial in the same issue written by three US academics who have long ben vehemently pro-helmet claims something all manufacturers never have, that cycle helmets are effective in reducing injuries in crashes involving motor vehicles.
And both the editorial and the research paper claim that a reduction in hospitalised head injuries is a result of greater helmet use. The possibility that less people may be cycling in a certain area is not entertained.
This is criticised by Dr. Meyer Hillman, author of Cycle Helmets: the case for an against (Policy Studies Institute).
[The three US academics] wont give up!
Hillman is mentioned in the BMJ editorial, and his idea that people take greater risks when they are wearing more protection is disparaged. He says one of the three US authors of the editorial has previously misrepresemted his views in a paper and could be the subject of future legal action.
But what is the impact on helmet and bike sales? Media horror stories of cycle-related head injuries may put people off cycling, rather than lead to an uplift in helmet purchases, says Hillman.
However, ‘Scoop’, a freelance contributor to bikemagic.com, believes the report should encourage "bare-headed" cyclists to go out immediately and buy bonce-protection: "Get yourself into a shop this weekend, and get yourself a lid now. With no exaggeration, everyone on bikemagic has had their lives saved by helmets and they’re the most essential piece of equipment you can own."
Press Association article:
CYCLE HELMETS `CAUSED DROP IN HEAD INJURIES’
By Tony Jones, PA News
The number of cyclists suffering serious head injuries in accidents has fallen by 12% over four years, mainly because more people now wear safety helmets, according to research published today.
Researchers from the Imperial College of Science, Technology and Medicine in London studied the different injuries caused to cyclists taken to casualty departments in English hospitals between 1991 and 1995.
The number of emergency admissions changed little over the four years, with 8,678 incidents in 1991, compared with 8,781 in the year 1994-95.
But the number of emergency admissions involving serious head injuries fell from 3,393 to 2,571 in the same period.
That represented a 12% fall in the proportion of cycling accidents involving head injuries, from 40% in 1991 to 28% in 1994.
Head injury cases fell by 9% among children aged six to ten, by 11% among the 11-15 age group and by 13% in cyclists aged over 16.
Previous research has shown that during that four-year period, more people, especially adults, began to wear cycling helmets.
The Royal Society for the Prevention of Accidents said that 173 cyclists were killed in road accidents in the UK last year.
A report produced for the European Commission and published earlier this year revealed the proportion of pedestrians and cyclists killed on UK roads is higher than anywhere else in the European Union.
The study found that, in 1996, 1,247 of Britain’s 3,740 road deaths involved cyclists and pedestrians.
But in the same year in France only one in six fatal road accidents involved bikers and walkers.
Extracts from the research paper in todays British Medical Journal.
Trends in serious head injuries among cyclists in England: analysis of routinely collected data
Adrian Cook, statistician, Aziz Sheikh, NHS R&D training fellow.
Department of Primary Health Care and General Practice, Imperial College School of Medicine, London W2 1PG
As the health and environmental benefits of cycling have become better appreciated, successive governments in the United Kingdom have encouraged cycle use. Cyclists, however, face considerable risk of injury, of which head injuries most commonly result in serious adverse outcomes. Despite evidence from case-control and time trend studies, 1 2 questions remain about the effectiveness of helmets, particularly for adults. We examined trends in emergency admissions for cycle injuries to English hospitals between 1991 and 1995, during which time the wearing of helmets increased (Research International Ltd, personal communication).3
Methods and results
All data on admissions to NHS hospitals are entered into the hospital episode statistics database. We studied the data for the period 1 April 1991 to 31 March 1995, at which time diagnoses were classified according to ICD-9 (international classification of diseases, ninth revision), and extracted all records concerning cyclists, whether their injuries resulted from bicycle accidents or motor vehicle accidents (codes E8261, E810-E825 fourth digit=6). From information in the primary diagnosis field, we identified head injuries as either "fracture of vault or base of skull" (ICD-9 800, 801) or "intracranial injury" (ICD-9 850-4). We used only data concerning emergency admissions and completed first episodes.
We used monthly counts to calculate the number of cyclists admitted with head injuries as a percentage of the total number of cyclists admitted and divided the patients into three age categories: junior (6-10 years), secondary (11-15 years), and adult (16 years and over). Using the percentage of head injuries per month as the outcome variable, we assessed trends over time for significance by fitting four linear regression modelsone to the complete dataset (figure) and one to each of the three age categories.
Of the 12.6 million emergency admissions in the study period, 35 056 (2.8%) were for injuries sustained while cycling. The average length of stay was 3.3 days. `Head injuries’ was the primary diagnosis in 34% (n=11 985) of these admissions, over half of which (n=7531) were among children aged <16 years. One per cent of cyclists (n=121) admitted with head injuries died as a result of their injuries.
Numbers of emergency admissions among cyclists changed little over the four years of the study period: from 8678 in 1991-2 to 8781 in 1994-5. However, the number with head injuries as the primary diagnosis fell from 3393 to 2571. The regression models showed a 12% reduction (95% confidence interval 10% to 15%)from 40% to 28%in the number of cyclists admitted with head injuries as a percentage of total monthly admissions. A reduction occurred in each age group during the study period. As a percentage of total admissions the reductions were estimated as: junior, 9% (95% confidence interval 3% to 16%); secondary, 11% (7% to 16%); and adult, 13% (11% to 16%).
Comment
The number of serious head injuries among cyclists fell markedly during a period of increasing helmet use, suggesting that helmets offer protection. Case-control studies have shown the benefit of wearing helmets,1 though inadequate control for possible confounding factors means that this conclusion is uncertain.4 Analysis of injury trends in Australia has also shown benefits,2 but these results were affected by a reduction in bicycle use when helmet wearing became compulsory. We accounted for any change in cycle use by using the total number of cyclists admitted as the denominator.
Our findings indicate that cycle helmets are of benefit both to children and, contrary to popular belief, to adults. The reason that people most frequently cite for not cycling is risk of injury; measures to increase cycle use must therefore address safety. Local publicity campaigns encouraging the voluntary wearing of helmets have been effective and should accompany national drives to promote cycling.
References
1. Thomspon RS, Rivara FP, Thompson DC. A case-control study of the effectiveness of bicycle safety helmets. N Engl J Med 1989; 320: 1361-1367
2. Cameron MH, Vulcan AP, Finch CF, Newstead SV. Mandatory bicycle helmet use following a decade of helmet promotion in Victoria, Australiaan evaluation. Accid Anal Prev 1994; 26: 325-327.
3. Wardle S, Iqbal Z. Cycle helmet ownership and wearing; results of a survey in South Staffordshire. J Public Health Med 1998; 20: 70-77.
4. McCarthy M. Do cycle helmets prevent serious head injury? BMJ 1992; 305: 881-882.
Editorial in BMJ:
Bicycle helmets: it’s time to use them
The evidence that they reduce head injuries is too strong to ignore
Bicycling is a worldwide activity. In both developed and developing countries it serves as an important means of transportation as well as an enjoyable recreational activity for adults and children. Thus, injuries related to bicycling are comparatively common, and head injuries account for one third of visits to emergency departments, up to two thirds of hospitalisations, and three quarters of deaths.1 Head injuries also carry a substantial risk of long term disability. Thus, preventing head injuries associated with this common, worldwide activity is important.
Safety helmets for bicycling have been available for at least 20 years. Although randomised controlled trials have become the gold standard for providing evidence of the effectiveness of clinical interventions, these trials are not feasible for examining whether helmets prevent head injuries. Given that the rate of head injury is about 20 injuries per 100 000 people, a randomised controlled trial would need to involve tens of thousands of people.2 Evidence for the effectiveness of helmets has come from two other types of studies: case-control studies, in which the proportion of people wearing helmets among cyclists with head injuries is compared with that of cyclists without head injuries, and ecological studies examining changes in the rate of head injury over time among populations wearing helmets and those not wearing helmets.
The strongest evidence for the effectiveness of helmets comes from case-control studies; this design is one of the cornerstones of modern epidemiology. A systematic review of five case-control studies, published in the Cochrane Library, found that helmets reduced the risk by 63-88% for head, brain, and severe brain injury among cyclists of all ages.1 Four of the studies controlled for a series of important covariates.3-6 Helmets seemed equally effective in reducing injuries in crashes involving motor vehicles and in accidents associated with falls and other causes.
In this week’s journal Cook and Shiekh (p 1055) describe a study that used an ecological time series analysis.7 Examining all admissions to NHS hospitals in England over a four year period, the authors found that head injuries as a proportion of monthly admissions for trauma related to bicycles fell from 40% in 1991-2 to 28% in 1994-5 while total emergency admissions for trauma related to bicycles did not change. These changes showed a consistent year to year trend in which the proportion of head injuries related to trauma from bicycles became lower in each successive year. Changes occurred in all age groups and are ascribed by the authors to an increase in the use of helmets. Similar findings from ecological studies have also been reported in the United States, New Zealand, and Australia 8 9 10 ; these findings were associated with an increased use of helmets occurring as a result of educational and legislative initiatives.
Despite this large body of evidence on the effectiveness of helmets in preventing head injuries in cyclists and their beneficial effects for populations of cyclists, critics, especially in the United Kingdom, continue to question the usefulness of helmets. Their criticisms fall into two main categories: "risk homeostasis" and lack of adjustment for other confounders. Hillman has argued that while helmets may offer some inherent protection to cyclists there is no overall benefit because cyclists who wear helmets ride in a less cautious manner so that their overall risk of injury is unchanged.11 This theory of risk homeostasis has been discussed for decades, but the evidence that it applies to helmet use and bicycling is non-existent.12 The other criticism is that case-control studies on helmets have not adequately controlled for all potential confounders, especially unmeasured factors such as differential risk taking behaviour in cases and controls. Adequate adjustment for differences between cases and controls is important for the validity of any case-control study. Four of the five studies in the Cochrane review controlled for potential differences between cases and controls, such as age and severity of the crash. 3 4 5 6 Crash severity can be used as a proxy for the hypothesised effects of risk taking behaviour. The magnitude of the protective effect of helmets found by these studies (threefold to eightfold ) makes it clear that unmeasured confounders cannot explain the differences in the risk of injury between cyclists who wear helmets and those who do not.
Healthcare providers and public policy makers have a duty to promote the health of the public and to base their recommendations on evidence of effectiveness. The evidence that bicycle helmets prevent head injuries is as strong as that for any injury prevention programme. While many programmes have their critics, the weight of the evidence for the effectiveness of helmets is strong; the evidence for a lack of protection is weak, circumstantial, and largely based on rhetoric. Further delays in promoting the use of helmets will be measured in the number of lives ruined by the devastating consequences of preventable brain injury.
Frederick P Rivara, professor of paediatrics.
Diane C Thompson, research scientist.
Harborview Injury Prevention and Research Center, Departments of Pediatrics and Epidemiology, Box 359960, 325 Ninth Avenue, Seattle, WA 98104, USA
Robert S Thompson, director.
Department of Preventive Care, Group Health Cooperative of Puget Sound, 1730 Minor Avenue, Suite 1600, Seattle, WA 98101, USA
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1. Thompson DC, Rivara FP, Thompson RS. Helmets for preventing head and facial injuries in bicycling. In: Cochrane Collaboration,ed. Cochrane Library. Issue 4. Oxford: Update Software, 1999.
2. Pitt WR, Thomas S, Nixon J, Clark R, Battistutta D, Acton C. Trends in head injuries among child bicyclists. BMJ 1994; 308: 177.
3. Thompson DC, Rivara FP, Thompson RS. Effectiveness of bicycle safety helmets in preventing head injuries: a case-control study. JAMA 1996; 276: 1968-1973[Medline].
4. Thompson RS, Rivara FP, Thompson DC. A case-control study on the effectiveness of bicycle safety helmets. N Engl J Med 1989; 320: 1361-1367[Medline].
5. Thomas S, Acton C, Nixon J, Battistutta D, Pitt WR, Clark R. Effectiveness of bicycle helmets in preventing head injuries in children. BMJ 1994; 308: 173-176[Abstract/Full Text].
6. Maimaris C, Summers CL, Browning C, Palmer CR. Injury patterns in cyclists attending an accident and emergency department: a comparison of helmet wearers and non-wearers. BMJ 1994; 308: 1537-1540[Abstract/Full Text].
7. Cook A, Sheikh A. Trends in serious head injuries among cyclists in England: analysis of routinely collected data. BMJ 2000; 321: 1055[Full Text].
8. Rivara FP, Thompson DC, Thompson RS, Rogers LW, Alexander B, Felix D, et al. The Seattle children’s bicycle helmet campaign: changes in helmet use and head injury admissions. Pediatrics 1994; 93: 567-569[Abstract].
9. Scuffham P, Alsop J, Cryer C, Langley JD. Head injuries to bicyclists and the New Zealand bicycle helmet law. Accid Anal Prev 2000; 32: 565-573[Medline].
10. Carr D, Skalova M, Cameron M. Evaluation of the bicycle helmet wearing law in Victoria during its first four years. In: Melbourne: Monash University Accident Research Centre, 1995. (No. 76.)
11. Hillman M. Cycle helmets: the case for and against. London: Policy Studies Institute, 1993.
12. Hedlund J. Risky business: safety regulation, risk compensation, and individual behavior. Injury Prev 2000; 6: 82-90[Medline].
