Bicycle helmet use by children

''Bicycle helmet use by children. Evaluation of a community-wide helmet campaign'', DiGuiseppi CG, Rivara FP, Koepsell TD, Polissar L. 1989. J Amer Med Assoc: 262:2256-61

Background
Bicycle helmet use by children is a paper by a team including Frederick P Rivara evaluating a helmet promotion scheme in Seattle, WA.

It is significant for two reasons:


 * It shows that Rivara and his Harborview team were already engaged in promoting helmets when the influential 1989 study was being prepared.
 * It includes a figure for helmet wearing rates in the community which is substantially different from the value used in the 1989 study; substituting this (measured) value for the estimated value in the 1989 study gives a result for helmet efficacy which is below the level of statistical significance and invalidates the major result of the 1989 study. As a co-author of the 1989 study, Rivara should have known and corrected this error.

Abstract
C. G. DiGuiseppi, F. P. Rivara, T. D. Koepsell and L. Polissar Children's National Medical Center, George Washington University School of Medicine and Health Sciences, Washington, DC.

To assess the effect of a community-wide bicycle helmet campaign on helmet use, we observed 9827 children riding bicycles at sites in high-, middle-, and low-income census tracts in Seattle, Wash (intervention city), and Portland, Ore (control city); observations were made during 2-week intervals before and 4, 12, and 16 months after the campaign's start. Helmet use increased from 5.5% before the campaign to 15.7% afterward in Seattle and from 1.0% to 2.9% in Portland. Strong associations were found between helmet use and white compared with black or other race; riding geared vs nongeared bicycles; riding at playgrounds, in parks, or on bicycle paths vs on city streets; and riding with adults or other children compared with riding alone. The proportions of helmet wearers, adjusted for these variables, increased from 4.6% to 14.0% in Seattle and from 1.0% to 3.6% in Portland, a significantly greater increase in use in Seattle compared with Portland. We conclude that a community-wide bicycle helmet campaign can increase helmet use among children.

Critique
Beyond the fact that Rivara's figures invalidate his own contemporaneous work, the premise of this study surely begs the question. Sure, promotion might increase helmet use. Does it also scare people off cycling, and does it result in lower head injury rates? These questions are not even considered.

To be fair, though, at this early date it is probably forgivable to believe that more helmet wearing is an unequivocal good. Later studies on a similar patter, such as those be Lee and Mann, are harder to forgive, because by then it should have been clear that simply increasing wearing rates in isolation is not a sufficient measure of the utility of any programme even tangentially related to cycle safety.