Effectiveness of bicycle safety helmets in preventing head injuries: a case-control study

Bicycle helmets can substantially reduce the risk of head and brain injury during accidents. Researchers analyzed the medical records of 3,390 injured bicyclists who were treated at 7 Seattle emergency departments. Half of those who suffered non-head injuries were wearing helmets compared to only 29% of those who sustained head injuries. Helmets reduced the risk of head and brain injury by approximately 65% to 70%. Hard-shell, thin-shell and no-shell helmets were equally protective. Both children and adults benefitted from the protection offered by a bicycle helmet.
Objectives.--To examine the protective effectiveness of bicycle helmets in 4 different age groups of bicyclists, in crashes involving motor vehicles, and by helmet type and certification standards. Research Design.--Prospective case-control study Setting.--Emergency departments (EDs) in 7 Seattle, Wash, area hospitals between March 1, 1992, and August 31, 1994. Participants.--- Case subjects were all bicyclists treated in EDs for head injuries, all who were hospitalized, and all who died at the scene. Control subjects were bicyclists treated for nonhead injuries. Main Results.--There were 3390 injured bicyclists in the study; 29% of cases and 56% of controls were helmeted. Risk of head injury in helmeted vs unhelmeted cyclists adjusted for age and motor vehicle involvement indicate a protective effect of 69% to 74% for helmets for 3 different categories of head injury: any head injury (odds ratio [OR], 0.31; 95% confidence interval [CI], 0.26-0.37), brain injury (OR, 0.35; 95% CI, 0.25-0.48), or severe brain injury (OR, 0.26; 95% CI, 0.14-0,48). Adjusted ORs for each of 4 age groups ( Conclusions.--Bicycle helmets, regardless of type, provide substantial protection against head injuries for cyclists of all ages involved in crashes, including crashes involving motor vehicles. JAMA. 1996;276:1968-1973