Teen driver risk in relation to age and number of passengers, United States, 2007-2010.

Objective: To provide updated estimates of the relationship between the number and ages of passengers present in a vehicle and the crash risk per mile driven of 16- and 17-year-old drivers.

Methods: Data on crashes that occurred in years 2007-2010 and data on the number of miles driven in years 2008-2009 were examined. Rates of crash involvement and driver death per mile driven were estimated for 16- and 17-year-old drivers with no passengers; with 1, 2, and 3 or more passengers younger than age 21 (and no older passengers); and with at least 1 passenger aged 35 or older.

Results: For 16- and 17-year-old drivers, having 1 passenger younger than age 21 (and no older passengers) was associated with 44 percent greater risk per mile driven of being killed in a crash, compared to having no passengers (relative risk [RR]: 1.44, 95% confidence interval [CI]: 1.01-2.04). Having 2 passengers younger than age 21 was associated with double the risk of being killed in a crash, compared to having no passengers (RR: 2.02, 95% CI: 1.36-2.99). Having 3 or more passengers younger than age 21 was associated with roughly quadruple the risk of being killed in a crash, compared to having no passengers (RR: 4.39, 95% CI: 1.45-13.31). The relative risk of being involved in any police-reported crash in the presence of young passengers followed a similar pattern; however, the differences in risks of being involved in any police-reported crash were smaller and were not statistically significant. Having at least 1 passenger aged 35 or older in the vehicle was associated with a 62 percent lower risk per mile driven of being killed in a crash (RR: 0.38, 95% CI: 0.24-0.60) and a 46 percent lower risk of being involved in any police-reported crash (RR: 0.54, 95% CI: 0.31-0.93) for 16- and 17-year-old drivers, compared to having no passengers.

Conclusions: These results show that although the overall number of teen driver fatalities has decreased substantially over the past several years, carrying young passengers is still a significant risk factor for young drivers. In contrast, carrying adult passengers is associated with significantly lower risk of crash involvement.