Epidemiology of bicycle injuries and risk factors for serious injury. 1997

Objective: To determine the risk factors for serious injury to bicyclists, aside from helmet use.

Design: Prospective case-control study.

Setting: Seven Seattle area hospital emergency departments and two county medical examiner's offices.

Patients: Individuals treated in the emergency department or dying from bicycle related injuries.

Measurements: Information collected from injured bicyclists or their parents by questionnaire on circumstances of the crash; abstract of medical records for injury data. Serious injury defined as an injury severity score>8.

Analysis: Odd ratios computed using the maximum likelihood method, and adjusted using unconditional logistic regression.

Results: There were 3854 injured cyclists in the three year period; 3390 (88%) completed questionnaires were returned. 51% wore helmets at the time of crash. Only 22.3% of patients had head injuries and 34% had facial injuries. Risk of serious injury was increased by collision with a motor vehicle (odds ratio (OR)=4.6), self reported speed >15 mph (OR=1.2), young age (<6 years), and age >39 years (OR=2.1 and 2.2 respectively, compared with adults 20-39 years). Risk for serious injury was not affected by helmet use (OR=0.9). Risk of neck injury was increased in those struck by motor vehicles (OR=4.0), hospitalized for any injury (OR=2.0), and those who died (OR=15.1), but neck injury was not affected by helmet use.

Conclusions: Prevention of serious bicycle injuries cannot be accomplished through helmet use alone, and may require separation of cyclists from motor vehicles, and delaying cycling until children are developmentally ready.