Report: A Word from the Cochrane Systematic Review Corner

In a recent issue of Injury Prevention, Rebecca Ivers, from the George Institute in Australia, published an important review of reports from the Cochrane Database of Systematic Reviews on bicycle helmet research(supernote 1).

The Cochrane Collaboration is a non-profit, non-governmental organization that produces and distributes systematic reviews of healthcare interventions, clinical trials, and other studies of interventions. The reviews are prepared by a group of health experts who undertake the reviews using a very specific protocol. When completed, the reviews are published and open for professional comments and criticisms by others. The reviews are available in most medical libraries, or for a fee, online. For more information, go to their website: www.cochrane.org.

There have been three reports on bicycle helmet research.

• Helmets for preventing head and facial injuries (2). In this review, the authors examined whether or not helmets reduced injuries in real-life. After examining 5 case control studies, they concluded that they were indeed effective, providing a 63-88% reduction in the risk of head, brain, and several brain injuries. They provided equal levels of protection for crashes involving motor vehicles (69% risk reduction) and from all other causes (68%).

• Non-legislative interventions (3). Even though helmets work, they are not universally used, and the authors of this review examined the effectiveness of non-legislative interventions to promote the use of helmets to school age children. Interventions such as health education programme, subsidized or free helmet distribution, media campaigns, and other kinds of interventions that included elements of all of these strategies were examined. In their review of 22 studies, there seemed to be an increase in helmet wearing that was statistically significant. Although no adverse effects were recorded from using these interventions, the authors cautioned that these interventions to promote helmet wearing may reduce cycling, and in turn result in negative health effects.

• Bicycle helmet legislation for increasing helmet use and prevention of head injuries (4).  This review examined the impact of legislation on bicycle-related head injury and helmet use. Other environmental and legislative changes like changes in cycling rates, bicycling paths, and lower motor vehicle speeding limits were taken into consideration. Only 3 of the 5 studies examined the impact legislation had on head injuries. Two of the studies showed a reduction in head injuries. One study reported a non-significant decline in the proportion of head injuries compared with other bicycle-related trauma. Helmet use did increase significantly, from 45% to 84% with the introduction or enforcement of helmet legilsation. None of these studies examined pre- and post-helmet legislation riding rates, and so the authors could not comment on the potential adverse effect of helmet legislation. The authors of the review concluded that although there was a protective effect of legislation on the reduction of head injury, more evaluation was needed, especially to measure actual helmet use and cycling rates.

In conclusion, Ivers – one of the world’s pre-eminent helmet researchers – poses a key question – “Where to from here?”

There remains socio-economic differences in injuries – poorer children have higher mortality rates, but also, what about helmet in low- and middle income countries? In places like India, bicyclists constitute 14% of the total road traffic deaths but only 5% of the riders. Intuitively, we believe that helmets could reduce head injury in low- and middle income countries as well, but we also need more evaluation to confirm this. And also we need more information of helmet design for the tropics, enforcement, and equity in helmet distribution.

• Ivers R. Cochrane Corner: Systematic reviews of bicycle helmet research. Inj Prevention 2007;13:190.
• Thompson DC, Rivara FP, Thompson R. Helmets for preventing head and facial injuries in bicyclists. Cochrane Database Syst Rev 1999;4:CD001855.
• Royal ST, Kendrick D, Coleman T. Non-legislative interventions for the promotion of cycle helmet wearing by children. Cochrane Database Syst Rev 2005;2:CD003985.
• Macpherson A, Spinks A. Bicycle helmet legislation for the uptake of helmet use and prevention of head injuries. Cochrane Database Syst Rev 2007;2:CD005401.

back to Headlines