Applying individual- and residence-based equity measures to characterize disparities in crash outcomes

Abstract

Introduction: Transportation safety priorities emphasize the importance of incorporating equity into efforts to reduce deaths and injuries. Using integrated data, we investigated relationships between individual- and residence-based measures of equity and rates of crash involvement in New Jersey, 2016–2019. Methods: We used statewide integrated data that includes linked crash reports, hospital discharge data, and residence-based equity measures. We calculated crash rates among drivers involved in and injured in a crash by residential census tract. Using generalized Poisson regression, we estimated rate ratios and 95% confidence intervals (aRR, 95% CI) in separate models for race and ethnicity categories and for six previously developed, multi-dimensional equity measures, controlling for driver sex and age. Results: We identified 1,629,219 drivers involved in crashes of whom 8.3% were injured. Hispanic and non-Hispanic Black drivers had higher rates of crash involvement than non-Hispanic White drivers (aRR, 1.67 [95% CI, 1.65–1.68] and aRR, 1.78 [95% CI, 1.77–1.80], respectively). For community equity measures, drivers who resided in census tracts with poorest equity scores had higher crash rates than those living in census tracts with most favorable equity scores (e.g., Index of Concentration at the Extremes: aRR, 2.10 [95% CI, 2.07–2.12]). We observed similar results for injury crash rates. Model fit improved for both all crashes and injury crashes models after adding each equity measure to baseline. Conclusions: Rates of all crashes and injury crashes were consistently higher among drivers of minoritized race and ethnicity groups and among those who lived in less equitable communities. Associations among crash rates and different equity measures provided similar evidence that disparities in traffic safety outcomes are related to inequity. Practical Applications: The usefulness of individual and residence-based equity measures lies in the opportunity to identify communities with higher crash risks for tailored intervention to improve traffic safety and to reduce disparities.