Can There be a Definitive Study of Bicycle Helmets and Head Injury?

Can a detailed, case-control study of bicycle helmets and head injuries be accurately accomplished? In response to an article critical of research methods used to measure the effectiveness of helmets in preventing brain and head injuries? The authors of this article, are researchers at the University of Washington’s Harborview Injury Prevention and Research Center and Group the Health Cooperative of Puget Sound. The authors of this article have also authored several case-control studies that have demonstrated helmet effectiveness.

At the root of the criticism, the authors note, are several misconceptions about case-control studies and injury research. The researchers noted that case-control studies regarding traffic injuries and death rates date back to at least 1938 – and that formal studies of such issues have been plentiful since the early 1960s.

One issue, say the researchers, is how a definitive case-control study regarding bicycle helmets and head injuries would be carried out.

A randomized trial would be large and expensive, they say. There would also be the ethical issues involved in calling on bicyclists participating in such a study to wear or, more importantly, not wear protective helmets.

By observing injured cyclists who come to emergency departments, or who have been admitted to hospitals and placing these groups into case or control groups according to their injuries, it is possible to fairly represent the “helmet wearing prevalence” of all cyclists who are involved in crashes.

But they add that no matter how many variables are considered and measured, no study can be considered perfectly free of possible, “confounding” errors.

Reference: Cummings P, Rivara FP, Thompson DC, Thompson RS Accident Analysis and Prevention, 2006 (in press)

Editor’s note: This article provides an excellent discussion about injury research methods and provides an explanation justifying the use of case-control studies for injury research.

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