Vehicle Model Year and Crash Outcomes: A CIREN Study

Abstract

Objective: To quantify the effect of model year (MY) on the occurrence of severe injuries and death after involvement in motor vehicle crashes.

Methods: Cases involving adult front seat occupants of vehicles MY ≥ 1994 equipped with frontal airbags were selected from the Crash Injury Research and Engineering Network (CIREN) database. Cases were grouped by MY: 1994–1997, 1998–2004, and 2005–2007 (MY groups [MYG] 1, 2, and 3, respectively. MYGs were compared in relation to mortality, Injury Severity Score (ISS), and the occurrence of Abbreviated Injury Severity score (AIS) 3+ and AIS4+ injuries to each body region using Mantel Haenszel chi-square, Kruskal-Wallis, and Bonferroni corrected t test. To adjust for confounders, multiple logistic regression models were built to explore the association of MYG with death. Covariates included age, BMI, delta v, principal direction of force (PDOF), restraint use, and vehicle type.

Results: A total of 1888 cases was distributed within MYG1 (34%), MYG2 (62%), and MYG (34%). Age, gender, BMI, and PDOF distribution did not differ among MYGs. Though ISS distribution was not different, a decrease in the occurrence of AIS4+ of the thorax and spine regions was noted over time. Mortality also decreased over time (18, 9, and 4% MYG 1, 2, and 3, respectively). Multivariate analysis revealed a protective effect of MYG2 and MGY3 (odds ratio [OR], 0.57 [0.44–0.75] and 0.22 [0.07–0.50], respectively) in relation to death.

Conclusions: Front seat occupants of later MY vehicles injured during crashes experience a decreased likelihood of very severe thoracic injuries, spinal injuries, and death.

Keywords:

• Crashworthiness
• CIREN
• Fatal crashes
• Injuries
• Vehicle model year
• Traffic accidents

ACKNOWLEDGMENTS

This work was performed for the Crash Injury Research and Engineering Network (CIREN) Project at the University of Maryland, National Study Center for Trauma and Emergency Medical Systems, in cooperation with the United States Department of Transportation/National Highway Safety Administration (USDOT/NHTSA). Funding has been provided by NHTSA under Cooperative Agreement Number DTNH22-05-H-01001. Views expressed are those of the authors and do not represent the views of the NHTSA.

Presented as a poster at the EAST 22nd Annual Scientific Assembly, January 13–17, 2009, Orlando, Florida.

Notes

^a Mantel Haenszel chi-square unless noted otherwise.

^b Kruskal-Wallis statistic.

^c Bonferonni t test.

^a Mantel Haenszel chi-square unless noted otherwise.

^b Bonferonni t test.

^c Kruskal-Wallis statistic.

^a Mantel Haenszel chi-square unless noted otherwise.

^b Compared to make year 1994–1997, 95 percent confidence intervals between parentheses.

^c Kruskal-Wallis statistic.

^a Normal weight, age 16–60, Δv < 40 km/h, Female gender, frontal PDOF, restrained status, automobile, make year 1994–1997 used as reference.

^a Model year 1993–1997 used as reference. Models 2005 and later excluded.

^b Adjusted by vehicular, crash, and occupant factors.