Female vs. male relative fatality risk in fatal motor vehicle crashes in the US, 1975-2020

Abstract

Motor vehicle accidents are the leading cause of death for young adults 18-29 years old worldwide, resulting in nearly 1 million years of life lost annually in the United States. Despite improvements in vehicle safety technologies, young women are at higher risk of dying in car crashes compared with men in matched scenarios. Vehicle crash testing primarily revolves around test dummies representative of the 50th percentile adult male, potentially resulting in these differences in fatality risk for female occupants compared to males. Vehicle occupants involved in fatal car crashes were matched using seating location, vehicle type, airbag deployment, seatbelt usage, and age. The relative risk for fatality (R) between males and females was calculated using a Double Pair Comparison. Young women (20s-40s) are at approximately 20% higher risk of dying in car crashes compared with men of the same age in matched scenarios. In passenger cars, 25-year-old female occupants in passenger car crashes from 1975-2020 exhibit R = 1.201 (95% CI 1.160-1.250) compared to 25-year-old males, and R-1.117 (95% CI 1.040-1.207) for passenger car crashes from 2010-2020. This trend persists across vehicle type, airbag deployment, seatbelt use, and number of vehicles involved in a crash. Known sex-based differences do not explain this large risk differential, suggesting a need for expanded test methodologies and research strategies to address as-yet unexplored sex differences in crash fatalities. These differences should be further investigated to ensure equitable crash protection.

Fig 1. Trends in annual vehicle fatality rates.

(A) Annual vehicle occupant fatalities involving vehicles manufactured in the prior five or 10 years. Annual fatalities for occupants in “recent-model” vehicles manufactured in the last five or 10 years have been generally declining as vehicle safety technologies have improved. (B) Annual vehicle occupant fatalities have decreased overall since 1975, yet fatalities among females have remained largely the same year-to-year.

Fig 2. Relative fatality risk, females vs. males, passenger car fatalities 2010–2020.

Relative fatality risk for all female occupants compared to males (n = 25,480; 2010–2020) under matched airbag deployment condition. Young female vehicle occupants are at an increased risk of fatality compared to males until ~40 years old.

Fig 3. Relative fatality risk, females vs. males, passenger car fatalities 1975–2020.

Relative fatality risk for female occupants compared to males (n = 249,160; 1975–2020) under matched airbag deployment condition. Young female vehicle occupants (driver, front right passenger, left and right second row passengers) in passenger cars are at an approximately 20% increased risk of fatality compared to males until ~40 years old.

Fig 4. Bootstrap estimates, females vs. males, passenger car fatalities 1975–2020.

Bootstrap estimates for relative fatality risk for female occupants compared to males under matched airbag deployment condition. 95% confidence intervals are derived from the middle 95% of these estimates.

Fig 5. Relative fatality risk, females vs. males, light truck fatalities 1975–2020.

Relative fatality risk for female occupants in light trucks compared to males (n = 92,826; 1975–2020) under matched airbag deployment condition. Young female vehicle occupants in light trucks (driver, front right passenger, left and right second row passenger) are at an approximately 20% increased risk of fatality compared to males until ~40 years old.