Impact of seat position on survival outcomes and anatomically specific severe injury patterns in four-wheeled motor vehicle accidents: a retrospective cohort study at a community emergency department in Japan

Abstract

Background: Road traffic accidents are a major healthcare concern worldwide. To improve outcomes for patients injured in motor vehicle crashes, it is crucial to understand the factors associated with mortality and anatomically specific injury severity. Seat position is one of the possible determinants of road traffic injury fatality; however, evidence regarding which seat positions are linked to impaired survival outcomes and anatomically severe injuries remains scarce.

Methods: We conducted a retrospective cohort study of patients injured in four-wheeled vehicle accidents between 2000 and 2022 and admitted to a community teaching hospital in Japan. Seat position was classified as driver seat, front passenger seat, or rear passenger seat. The primary endpoint was in-hospital mortality. Other outcomes included severe trauma, defined as an Injury Severity Score (ISS) of > 15, and anatomically specific severe injuries of the head and neck, chest, abdomen, pelvis, and extremities, defined as an Abbreviated Injury Scale score of ≥ 3.

Results: Among 5,906 eligible patients, 4,104 (69.5%) were driver seat occupants, 1,009 (17.1%) were front passenger seat occupants, and 793 (13.4%) were rear passenger seat occupants. After adjusting for potential confounders such as age, sex, admission year, season, presentation time, presentation day, prehospital length of stay, vehicle configuration, collision type, seatbelt use, airbag deployment, and involvement in high-energy trauma using logistic regression analysis, rear passenger seat occupants had a lower risk of hospital mortality (adjusted odds ratio [AOR], 0.396; 95% confidence interval [CI], 0.216-0.727) and a lower risk of severe trauma with an ISS of > 15 (AOR, 0.428; 95% CI, 0.308-0.596) than driver seat occupants. Additionally, rear seat occupants were less likely to sustain serious injuries to the chest (AOR, 0.474; 95% CI, 0.333-0.673) and abdominal or pelvic contents (AOR, 0.373; 95% CI, 0.218-0.639) than driver seat occupants.

Conclusion: Our results suggest that driver seat occupants require special attention because of their higher risk of adverse outcomes and anatomically severe injuries. These findings will be useful for vehicle occupants, emergency medical professionals, and automobile manufacturers.

Clinical trial number: Not applicable.

Keywords: Driver seat; Front passenger seat; Rear passenger seat; Severe trauma; Traffic accidents.

Fig. 1

Participant flow chart. ED, emergency department

Fig. 2

Odds ratios for in-hospital mortality among study participants. The reference group is the driver seat occupants. In the multivariable analysis, the rear passenger seat position was associated with a lower risk of mortality than the driver seat position. ^aAdjustment for potential confounders: age, sex, admission year, season, presentation time, presentation day, prehospital length of stay, vehicle configuration, collision type, seatbelt use, airbag deployment, and involvement in high-energy trauma. ^bGood model fit was verified by the Hosmer–Lemeshow test (p = 0.252); the c-statistic for the model was 0.880. OR, odds ratio; CI, confidence interval. *p < 0.025

Fig. 3

Odds ratios for severe trauma with ISS of > 15 and anatomical site-specific severe injury with AIS score of ≥ 3 for each body component among study participants. The reference group is the driver seat occupants. In the multivariable analysis, the rear passenger seat group exhibited a lower risk of severe trauma with an ISS of > 15 and severe injuries to the chest and abdominal or pelvic contents than the driver seat group. ^aAdjustment for potential confounders: age, sex, admission year, season, presentation time, presentation day, prehospital length of stay, vehicle configuration, collision type, seatbelt use, airbag deployment, and involvement in high-energy trauma. ^bGood model fit was verified by the Hosmer–Lemeshow test (p = 0.101); the c-statistic for the model was 0.860. ^cGood model fit was verified by the Hosmer–Lemeshow test (p = 0.184); the c-statistic for the model was 0.813. ^dGood model fit was verified by the Hosmer–Lemeshow test (p = 0.107); the c-statistic for the model was 0.851. ^eGood model fit was verified by the Hosmer–Lemeshow test (p = 0.275); the c-statistic for the model was 0.848. ^fGood model fit was verified by the Hosmer–Lemeshow test (p = 0.598); the c-statistic for the model was 0.847. AIS, Abbreviated Injury Scale; ISS, Injury Severity Score; OR, odds ratio; CI, confidence interval. *p < 0.025