49th ANNUAL PROCEEDINGS
ASSOCIATION FOR THE ADVANCEMENT OF AUTOMOTIVE MEDICINE
September 12-14, 2005
EFFECTIVENESS OF HIGH BACK AND BACKLESS BELT-
POSITIONING BOOSTER SEATS IN SIDE IMPACT
Kristy B. Arbogast*, Michael J. Kallan+, Dennis R. Durbin*+
*The Department of Pediatrics
The Children’s Hospital of Philadelphia
+The Center for Clinical Epidemiology and Biostatistics
The University of Pennsylvania School of Medicine
Previous work quantified a 59% reduction in injury risk for children
in belt positioning booster seats (BPB) compared to those restrained
in seat belts using a sample of crashes of all directions of impact.
Experimental sled tests have highlighted the potential for extreme
occupant excursion out of the BPB in side impact crash conditions.
Using data from a large child specific crash surveillance system, the
present study built upon these previous studies and quantified the
relative effectiveness of BPB as compared to seat belts in reducing
the risk of injury among 4-8 year olds in side impact crashes.
Children in BPB were at a 58% reduction in risk of injury than those
in seat belts in side impact crashes. This result varied by booster seat
type: those in high back BPB were at a 70% reduction in injury risk
while those in backless BPB did not experience a statistically
significant reduction in injury risk compared to those in seat belts.
This differential performance of the two types of BPB provides
direction for future research into the design and performance of these
The protection of children in side impacts has attracted
considerable attention in the safety community as these crashes
represent a significant burden on society. Analyses of the Fatal
Analysis Reporting System (FARS) demonstrated that 42% of the
fatalities of rear seat child occupants age 0-8 were in side impact
crashes (National Highway Traffic Safety Administration 2003).
Several studies have examined the injury and fatality pattern
for children in side impact crashes. In analyses of children from 0-14
years of age admitted to a trauma center, Orzechowski et al
documented injuries of elevated severity in side impacts as compared
to frontal crashes and further identified a pattern of injuries in side
impact crashes to include those to the head, cervical spine and chest
(Orzechowski et al. 2003). Our previous work demonstrated that the
benefits of rear seating previously shown for frontal crashes extended
to side impact crashes for children age 0-15 years (Durbin et al.
2001). Howard et al examined the role of seat position on the injury
risk to children age 0-12 years in side impact crashes using a sample
of children admitted to two trauma centers as well as analyses of the
National Automotive Sampling System (NASS) and FARS. In this
study, the elevated injury and fatality risk associated with the struck
side seat position was highlighted (Howard et al. 2004). All of these
studies focused on children of a broad age range, thus including an
array of restraint conditions limiting the applicability of the findings
to a particular restraint type. Only two studies have focused their
study of side impact protection for children on a specific restraint:
both examined injury or fatality risk to children in harnessed-based
child restraint systems (Sherwood et al. 2003; Arbogast et al. 2004).
In the past five years, there has been tremendous focus on the
benefits of booster seats as compared to seat belts. In a study of 4-7
year olds, those in belt-positioning booster seats (BPB) experienced a
59% reduction in injury risk compared to those restrained in seat
belts (Durbin et al. 2003). This analysis was conducted on a study
sample that, although it included all directions of impact, was
composed of over 50% frontal crashes. To date, no study has
examined the field performance of these restraints in side impact
crashes. Experimental sled tests have highlighted the potential for
extreme occupant excursion out of the BPB in lateral crash
conditions. In a test matrix utilizing high back and backless BPB in
30- and 90-degree far side impacts, significant lateral movement was
present in both restraint systems exacerbated by relative slipping
between the booster seat and the vehicle seat. The dummy’s upper
torso slipped out of the shoulder belt in all tests resulting in large
head excursions and the potential for head contact with vehicle
interior (Mallot et al. 2004).
Therefore, the objective of this analysis was to build on
previous work and determine if the previously documented benefits
of BPB over seat belts in reducing child injury risk extend to side
impact crashes. Specifically, we quantified the relative effectiveness
of belt-positioning booster seats, both backless and high back, as
compared with seat belts alone in reducing the risk of injury among
4-8 year old children in side impact crashes.
STUDY POPULATION AND DATA COLLECTION - Data
for the current study were drawn from the Partners for Child
Passenger Safety (PCPS) program, collected from December 1, 1998
for Child Passenger Safety (PCPS) program, the source of data for
this study. The authors also thank the many State Farm
policyholders who consented to participate in PCPS. The results
presented in this report are the interpretation solely of the author(s)
and are not necessarily the views of State Farm.
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