Question:
I live in the U.S. The major increase in helmet use roughly coincided with a huge increase in the number of SUVs and vans on the roads. In a collision, a cyclist stands a much higher chance in an accident of hitting his or her head in the primary impact with a motor vehicle than when vehicles were smaller. And your citation for this is? Bearing in mind that there is a similar growth in the number of SUVs in the UK, albeit delayed by a couple of years, and no such increase is visible here... Let me take a stab at this--can you reject as clearly wrong either or both of the following formulations: helmets cause an "85% reduction in _fatal_ head and/or brain injuries"? or helmets cause an "85% reduction in bicycling _fatalities_"?

Answer: I don't think anyone seriously claims an 85% reduction in fatalities, nor in fatal head injuries - that is mostly a strawman Krygowski et al. like to bring up. If you see something in an advertising blurb, that is almost by definition not a serious claim - they'll say anything that helps sell their wares as long as they won't go to jail or be fined too much for it. We are not, however, discussing advertising. Overall, helmets were found to prevent 69 percent of head injuries, 65 percent of brain injuries, and 74 percent of severe brain injuries" *but* these authors use the following definitions: Head injury: All injuries to the forehead, scalp, ears, skull and brain, including superficial lacerations, abrasions and bruises on the scalp, forehead and ears, as well as skull fractures, concussion, cerebral contusions and lacerations and all intracranial hemorrhages (subarachnoid, subdural, epidural Brain injury: A diagnosis of concussion or more serious intracranial injury, excluding skull fractures without accompanying brain injury. Severe brain injury: An intracranial injury or hemorrhage, including all cerebral lacerations/contusions, and subarachnoid, subdural and extradural hemorrhages.

Clearly the definition of a severe brain injury includes injuries far less severe than what a casual reader would think of as severe (which might require a bit of the brain squirting out through the skull, or something equally grizly.) These authors, who include Frederick Rivara, state that their results are consistent with their 1989 results. Obviously even their earlier work is being misrepresented by allowing readers to imagine injuries far different than what they were actually talking about..