The 1989 case/control study by Thompson, Rivara and Thompson is the most widely quoted 'helmets save lives' claim, citing a 85 percent reduction in head injuries and 88 percent in brain injuries. Such claims have never been confirmed in studies of large populations and have long been lambasted by those opposed to compulsory helmet laws.
Now there's a review in an influential journal to back up those who pour scorn on Thompson, Rivara and Thompson, said Avery Burdett, chairman of the Ontario Coalition for Better Cycling.
"In the past, Thompson, Rivara and Thompson have rejected all criticisms of their review and simply re-stated their claims. They might find it more difficult to do the same to criticisms in a refereed article in a reputable journal," said Burdett.
Australian academic W.J Curnow wrote the report and is scathing of Thompson, Rivara and Thompson's methodolgy and the helmet compulsion laws based on their much criticised findings:
"The study concludes that the association between wearing helmets and reduced head injury is compelling and legislation is likely to help, but this is hardly credible because it also admits to not answering the crucial question of cause and effect.
"Demand for protection of the head stems from fear of fatal and disabling injury to it. A public accustomed to soldiers, miners and construction workers wearing protective helmets naturally looked to the similar products on offer for cyclists, not realising the critical difference between protecting the brain within a stationary head struck by a fast-moving object and that of a moving person in collision. Due to their evolution, bicycle helmets are more suited to the former purpose than what they are used for. This undesirable result has come about because the design of helmets has not been guided by research on mechanisms of brain injury. Consequently, bicycle helmets have been a controversial issue for 20 years or more."
And Thompson, Rivara and Thompson's work was based on heavy, hardshell helmets, no longer produced:
"Due to the decline in use of hard-shell helmets, past findings of their efficacy are not applicable to most helmets now used."
Curnow said Thompson, Rivara and Thompson's studies did not possess "scientific rigour."
And this is the point that has been raised with the British Medical Association. Last year it changed its stance on helmet compulsion: the BMA went from pro-helmet, anti-compulsion (based on its own 1999 report) to a stance of helmet compulsion for all adult and child cyclists.
The BMA has promised to review this decision. The report in Accident Analysis & Prevention will be used by anti-compulsionists to show that the BMA did not use "scientific rigour" when it over-turned the advice of its own 1999 report, using erroneous death stats provided by the Bicycle Helmet Initiative Trust, a political lobbying organisation funded by the Freemasons.
The full reference is: Curnow, W.J., 2005. The Cochrane Collaboration and bicycle helmets. Accid. Anal. Prev. 37 (3) 569-574.
Ontario Coalition for Better Cycling: http://www.magma.ca/~ocbc
There are 46 articles on helmet compulsion in the link below. BikeBiz.com is fiercely pro-helmet but anti-compulsion.