Do Bicycle Helmets Protect, and Should They Be Mandatory?-Reply

Abstract

In Reply. —Drs Bayliss and Goldman express philosophical positions against mandatory helmet laws. Their arguments do not stand up to scientific scrutiny. Furthermore, they both demonstrate a misunderstanding of the validity of well-conducted case-control studies. 1 All the cyclists in our studies had experienced a bicycle crash, thus all could potentially have sustained a head injury. Therefore, the major potential confounding factors to be evaluated are the crash forces experienced by both case and control groups (speed, surface, motor vehicle involvement) so that the protective effect of helmets can be estimated. Our study took such an approach. We agree that bicycling is beneficial to the environment and to personal physical health. This is all the more reason to publish studies that offer bicyclists a way to avoid their most serious hazard, head injury. Contrary to Bayliss' statement, fatality risk studies that compare bicycle travel with motor vehicle and motorcycle travel using the