The Scope and Nature of Injuries to Rear Seat Passengers in NSW Using Linked Hospital Admission and Police Data

Abstract

Objective: To compare the pattern of injuries to front and rear seat occupants and test the hypothesis that rear seat passengers of different ages sustain different patterns of injury. Method: Patients admitted to a hospital following involvement in a crash in New South Wales (NSW) Australia between 2005 and 2007 were identified using International Classification of Diseases (10th edition [ICD10]) codes. Hospital admissions data were linked with NSW police crash data using probabilistic techniques. The profiles and patterns of injury of front and rear seat passengers were compared. Logistic regression was used to examine how age influenced the pattern of injury among rear seat passengers. Results: Sixty-three percent of hospital admissions were linked with police records. One in 5 passengers were rear seat passengers. There were more unrestrained occupants in the rear (7%) compared to drivers (3%) and front seat passengers (2%). Younger (9–15 years) injured passengers were seated in the rear more often than in the front passenger position and older injured passengers (>50 years) were seated more often in the front passenger position than in the rear (15% rear compared to 5% front aged 9–15 years; 22% rear compared to 37% front aged >50 years; χ2, P < .001). There were proportionally more fatal injuries among rear seat passengers (10%) than among drivers (5%) and front seat passengers (6%), and the pattern of injury between front and rear passengers also varied. Rear seat passengers had more head and abdominal injuries and fewer thoracic and knee/lower leg injuries than front seat passengers. After adjusting for vehicle age, restraint status, travel speed, and whether or not a fatality occurred in the crash, older (>50 years) rear passengers had 6.3 times the odds of sustaining thoracic injuries (95% confidence interval [CI], 2.6–15.0) and lower odds (odds ratio [OR] = 0.4, 95% CI, 0.2–0.9) of sustaining abdominal/lumbar injuries than the youngest occupants (9–15 years).The odds of sustaining a head injury did not vary with age, and the odds of sustaining thoracic, abdominal, or lower extremity injuries did not differ significantly between rear seat passengers aged 16–50 years and 9–15 years. Conclusions: The findings suggest that there is a need for enhanced protection for rear seat passengers, because they have proportionally more fatal injuries than front-seated occupants. The frequency of abdominal injury and the differences between injury patterns observed in front seat passengers suggests a potential benefit from adding abdominal injury risk assessment to rear seat occupant protection test protocols. There is also scope to improve chest protection for older rear seat passengers.