Introduction
Community-level factors, including environmental characteristics, are known to influence traumatic injury severity, but their role in motor vehicle collision (MVC) outcomes remains poorly understood. Understanding how environmental conditions contribute to injury patterns may help inform community-based prevention strategies. We used a systems-level approach to examine the impact of environmental justice and urbanicity on injury severity following MVCs.
Methods
We conducted a retrospective cohort study of adult patients presenting to the emergency department after MVCs between 2012 and 2024, using data from the Michigan Trauma Quality Improvement Program (MTQIP), representing 12 hospitals. Crash-site ZIP codes were linked with external datasets capturing environmental exposures. Urbanicity was classified using the 2020 Rural–Urban Commuting Area (RUCA) codes, and environmental burden was assessed using the Environmental Justice Index (EJI). The primary outcome was Injury Severity Score (ISS), with mortality as the secondary outcome. We developed multivariable logistic regression models adjusting for patient demographics and MVC characteristics.
Results
Among 23,309 MVC patients (mean age 42.6 ± 21.1 years; 52.9% male; 64.9% White), 18.2% had an ISS >15. Crashes occurred in locations with a mean EJI of 0.58 ± 0.29, and 68% occurred in metropolitan areas. Greater injury severity (ISS >15) was significantly associated with higher rurality (RUCA 9: OR 1.37, 95% CI 1.35–1.59, p=0.04), older vehicle age (1970–1989: OR 2.41, 95% CI 1.62–3.58, p<0.001), and airbag deployment (OR 1.47, 95% CI 1.35–1.59, p<0.001). Injury severity was lower but borderline significant with higher EJI (OR 0.87, 95% CI 0.77–1.00, p=0.05) and significantly lower with seatbelt use (OR 0.32, 95% CI 0.29–0.36, p<0.001). Neither EJI nor RUCA predicted mortality.
Conclusion
In this multicenter cohort, low urbanicity was associated with higher MVC injury severity, whereas higher environmental justice scores correlated with lower severity. Known modifiers, including vehicle age, airbag deployment, and seatbelt use, also influenced outcomes. These findings highlight the role of community-level environmental factors in MVC-related trauma and suggest opportunities to target high-risk geographic regions for injury prevention.