Using trauma center data to identify missed bicycle injuries and their associated costs.

BACKGROUND: Recently, there has been a 58% increase in the number of observed cyclists in San Francisco. In 2009, 3.2% of commuters were traveling by bicycle in this city, which is well above the national average of less than 1%. Police reports are the industry standard for assessing transportation-related collisions and informing policies and interventions that address the issue. Previous studies have suggested that police reports miss a substantial portion of bicycle crashes not involving motor vehicles. No study to date has explored the health and economic impact of cyclist-only (CO) injuries for adults in the United States. Our objective was to use trauma registry data to investigate possible underrepresentation of certain cyclist injuries and characterize cost.

METHODS: We reviewed hospital and police records for 2,504 patients treated for bicycle-related injuries at San Francisco General Hospital (SFGH). We compared incidence, injury severity, admission rate, and cost of injury for CO and auto-versus-bicycle (AVB) injuries treated at SFGH. We then calculated the cost of injury.

RESULTS: Of all bicycle-related injuries at SFGH, 41.5% were CO injuries and 58.5% were AVB injuries. Those with CO injuries were more than four times as likely to be required of hospital admission compared with those with AVB injuries (odds ratio, 4.76; 95% confidence interval, 3.93-5.76; p < 0.0001). From 2000 to 2009, 54.5% of bicycle injuries treated at SFGH were not associated with a police report, revealing that bicycle crashes and injuries are underrecognized in San Francisco. Costs for care were significantly higher for AVB injuries and increased dramatically over time; total cost for CO and AVB injuries were $12.6 and $17.8 million.

CONCLUSION: Based on this study, we conclude that trauma centers can play a key role in future collaborations to define issues and develop prevention strategies for CO crashes.

LEVEL OF EVIDENCE: Epidemiologic study, level II.