Multivariate ANALYSIS of Restraint USE and Injury Severity among Older Child Passengers

INTRODUCTION

Road traffic injuries kill over 1.2 million people worldwide each year and seriously injure an additional 50-60 million people. Furthermore, child passengers account for 10% of all crash victims in the United States and road traffic injuries are the leading cause of death for children between the ages of 3-14. This study focuses on older child passengers between the ages of 9 and 12, a population frequently overlooked in automotive safety research and policy.

BACKGROUND

Older children are significantly more likely than younger children to suffer road traffic injuries. This may be because restraint use among older children is significantly lower. Also, older children are more likely to ride in the front seat of the car, a position which may expose them to more severe injury. Additional risks arise from the use of an inappropriate restraint or the improper use of the correct restraint. Furthermore, industry and federal regulations do not mandate safety devices or restraints for older child passengers between the ages of 8 and 14. Using inappropriate and improper restraints may lead to serious injury in older children as well. Older children are at higher risk for cervical spine injuries, abdominal injuries, and serious head injuries related to the restraint. Proper vehicle engineering and safety devices play an important role in reducing unnecessary injuries to older child passengers.

METHODS

The objective of this study is to evaluate the relationship between restraint use and injury severity in older child passengers in the United States between 1991 and 2005. Secondary data analysis was performed using the NHTSA NASS-CDS data system. The NASS-CDS data system is a complex automotive crash sampling system that utilizes a complex sample design that includes 32 PSUs across the United States and a weighting factor. This study looked at a subset of the data that included children between the ages of 9 and 12 who were involved in tow-away and inspected collisions.

Restraint use was compared with injury severity along with other potential risk factors, potential confounders and effect modifiers, which included seating position, crash type, vehicle type, age, height, and weight. Descriptive statistics were obtained to characterize the study population, and stratified analysis and multivariate logistic regression were utilized to assess the association between restraint use and injury severity while controlling for confounders and effect modifiers.

RESULTS

Overall, descriptive statistics demonstrated that no restraint and serious injury are positively associated with a crude OR=4.74; 95% CI=2.6, 8.7. Seating position, vehicle type, and weight were significantly associated with restraint use. Also, crash type was significantly associated with serious injury. Study results showed that among children between the ages of 9 and 12 who were unrestrained, after controlling for crash type and vehicle type, the odds of experiencing a serious injury was higher than for those restrained, adjusted Mantel-Haenszel OR=4.53.

DISCUSSION

These findings combined with past literature, suggest that there is a strong relationship between restraint use and injury severity that is maintained even when controlled for significant cofactors. However, it is suggested that the protective effects of restraints could be further enhanced to protect older child passengers. This includes providing size-appropriate restraints that will be properly used by older child passengers. Integrated child seats and appropriately tested and reliable booster seats would protect older children further and prevent injuries caused by using inappropriate or improper restraints. Also, crash testing should include dummies that mimic size (height and weight) of all children to help design a safer vehicle interior and for seat belt and safety device testing. Furthermore, these recommendations should not only be used to alleviate the burden of injury among older child passenger in the United States, but also be implemented in developing nations where the risk for automotive injuries are significantly higher.