Jermakian 1 ABDOMINAL INJURY RISK FOR CHILDREN SEATED IN BELT POSITIONING BOOSTER SEATS Jessica Steps Jermakian Center for Injury Research and Prevention at The Children’s Hospital of Philadelphia

Previous studies have demonstrated that booster seats reduce the risk of seat belt syndrome, in particular the occurrence of abdominal organ injuries, by improving the fit of the seat belt on young children and encouraging better posture and compatibility with the vehicle seat itself. However, other researchers have shown that abdominal injuries are still prevalent even with the use of booster seats. In the US, as booster seat use increases and more data become available, particularly on older children in booster seats, the abdominal injury risk to these children should be revisited. Therefore the objective of this study was to quantify the time trend increase in appropriate restraint for rear row(s) seated children age 4 to 7 years old and define the prevalence of abdominal injuries in those restrained by beltpositioning booster seats. A probability sample of 4,517 crashes involving 5,259 children, weighted to represent 89,588 children in 77,153 crashes was collected from an on-going child specific crash surveillance system between December 1, 1998, and December 31, 2005. Appropriate restraint, including the use of belt positioning boosters, increased from 17% to 67% among 4 to 7 year olds during the time period of data collection. In frontal impacts, abdominal injuries occurred among 0.25% of all 4to 7-year-olds, including 0.32% of those in seat belts and 0.04% of those in belt-positioning booster seats. Among children restrained in belt positioning booster seats, we were not able to detect a difference in the risk of abdominal injuries between the age groups This study, conducted on a dataset with increased booster use by 6 and 7 year olds, confirms previous analyses that point to a reduced abdominal injury risk for children in belt-positioning booster seats. Abdominal injuries still occurred in some boosterseated children, however, suggesting the need for further in-depth study into the circumstances surrounding these injuries. INTRODUCTION Abdominal injuries are the second to head and face injuries in young children using adult seat belts. [1] Reported injuries to this region focus on “seat-belt syndrome”, which consists of belt-induced abdominal injuries and lumbar spine fractures. [2-6] While all children are at risk of developing seat belt syndrome, the poor fit of the belt in younger children likely places them at higher risk than older children. In a study of abdominal injuries in belted children, the scenarios resulting in injury involved several vehicle and child factors such as seat belt geometry not ideal for children (e.g. a shallow lap belt angle), position of the shoulder belt behind the back or slouched posture to position the knees over the edge of the seat. [7] The use of a belt positioning booster seat (BPB) improves these factors by improving the fit of the seat belt on young children and encouraging better posture and compatibility with the vehicle seat itself. They are the recommended restraint for 4 to 8 year old children according the American Academy of Pediatrics and National Highway Traffic Safety Administration. Booster seats are designed to improve lap and shoulder belt fit on children, minimizing the factors that result in abdominal injury. Our previous research has confirmed this in real world crashes by showing booster seats reduce the risk of injury to children age 4-7 years old by 59% compared to similar age children in adult seat belts. This reduction in injury risk was particularly evident in the abdomen, resulting in 0 injuries per 1,000 booster seat restrained children in crashes versus 4.4 per 1,000 for children in belts. [1] This analysis conducted on data from 1998 to 2002 was based primarily on children age 4 and 5 years of age due to the usage practices during that time period. In the time since this research was published, however child restraint use including booster seats among children age 4 to 8 years of age has improved by 54% [8] and, as more children, in particular older children, are appropriately restrained in booster seats,