According to the National Center for Health Statistics, the total resident population of the United States increased from 151 million in 1950 to 296 million in 2005, representing an average annual growth rate of 1.2 percent. As the population ages, there is a growing need for vehicle safety to suit older occupants. This study examines the relationship between age and the incidence of thoracic injuries in different motor vehicle crashes. The National Automotive Sampling System/Crashworthiness Data System (NASS-CDS) for the years 1998 to 2007 was used to measure the relationship between occupant’s age and the incidence of thoracic injuries. NASS-CDS only includes crashes involving at least one passenger vehicle towed due to damage. Results showed that the age group 75 and older (75+) had a higher percentage of Abbreviated Injury Scale (AIS) moderate or more severe (2+) thoracic injuries when driving or riding in any passenger vehicle type compared to three other age groups in a tow-away crash. Age groups 25 to 44, 45 to 64 and 65 to 74 had a lower percent of thoracic injuries when driving or riding in utility vehicles, pickup trucks, and vans, referred to collectively as LTVs, compared to passenger cars. However, age group 75+ had a higher percentage of thoracic injuries when driving or riding in LTVs compared to cars. Data analysis showed that seat belt use has a positive impact in reducing the incidence of a moderate or more severe thoracic injury among all age groups in towaway crashes. However, even when controlling for restraint use, the incidence of thoracic injuries among the four age groups shows a steady increase for both belted and unbelted occupants as age increases. The analysis results by occupants’ seating position showed that people 75+ had a higher incidence of AIS 2+ thoracic injuries than other age groups in the same seating position. Furthermore, people 75 and older had an exceptionally higher incidence of AIS 2+ thoracic injuries when riding in the rear seats at an estimate of 18.7 percent compared to drivers and front-seat passengers of the same age group. Data analysis of the incidence of AIS 2+ thoracic injuries by vehicle model year showed that young and middle-age groups had lower incidence of thoracic injuries when driving or riding in vehicles of model year 1996 or later compared to model years before 1996. However, for occupants 75+ the incidence of thoracic injuries was slightly higher in vehicle model years 1996 and later. The incidence of thoracic injury remains in a steady increasing pattern in relation to occupants’ age in both single- and two-vehicle crashes. Both age groups 65 to 74 and 75+ had higher bony structures injuries as indicated by an estimate of 79 percent and 23 percent of the occupants sustaining rib cage and sternal fractures. Lung contusions and lacerations were sustained by an estimated 20 percent of occupants 75+. The steering wheel was the most common source of injury among young and middle-age group occupants, while seat belt was reported as the source of thoracic injuries among occupants 75+. (Author/publisher)
Abstract