ARTICLE
Improvement in Booster Seat Use in Tennessee
Veronica L. Gunn, MD, MPHa, Rhonda M. Phillippi, RNb, William O. Cooper, MD, MPHa
aChild and Adolescent Health Research Unit, Department of Pediatrics, andbDivision of Pediatric Critical Care, Emergency Medical Services for Children, Vanderbilt
University School of Medicine, Nashville, Tennessee
The authors have indicated they have no financial relationships relevant to this article to disclose.
ABSTRACT
OBJECTIVE.Tennessee enacted an enhanced child safety restraint law in July 2004, which included new requirements for booster seat use among 4- to 8-year-old children. The goal of this study was to evaluate the appropriate use of child safety restraints and knowledge of the enhanced law before and after its implementation.
METHODS.On-site child safety restraint assessments and brief driver interviews for cars with passengers 0 to 8 years of age were conducted at 34 sites in 3 urban counties in Tennessee. Assessments were conducted 2 to 3 months before imple-mentation of the law and 1 year after impleimple-mentation of the law. Appropriateness of restraint use was defined on the basis of language in the enhanced law.
RESULTS.Data were obtained for 1247 child passengers transported by 1191 drivers; 333 of the children were 0 to 3 years of age, and 914 were 4 to 8 years of age (the primary age group targeted by the enhanced law). Significant improvement in appropriate booster seat use was seen for 4- to 8-year-old passengers after imple-mentation (39%), compared with use before impleimple-mentation (29%). There was no improvement in the rate of appropriate restraint use for younger children (⬍4 years of age) after implementation. Black passengers 4 to 8 years of age were twice as likely as white child passengers to be unrestrained, before and after implemen-tation. Seventy-nine percent of drivers reported awareness of the new restraint law after implementation; the majority of drivers obtained information from television advertisements.
CONCLUSIONS.Improvements in booster seat use were seen after adoption of an enhanced state law requiring use; however, racial differences in restraint use persisted among 4- to 8-year-old passengers. Additional study of barriers to booster seat use among drivers of black child passengers and unrestrained children is warranted.
www.pediatrics.org/cgi/doi/10.1542/ peds.2006-1876
doi:10.1542/peds.2006-1876
Key Words
booster seats, child passenger safety, injury prevention
Abbreviation CSR— child safety restraint Accepted for publication Aug 9, 2006
Address correspondence to Veronica L. Gunn, MD, MPH, Department of Pediatrics, Child and Adolescent Health Research Unit, Vanderbilt University School of Medicine, AA-0216 MCN, 1215 21st Ave South, Nashville, TN 37232-2504. E-mail: veronica.gunn@vanderbilt.edu
I
NJURIES SUSTAINED IN motor vehicle crashes remain the leading cause of morbidity and death for US chil-dren⬎1 year of age. In 2004, 2033 childrenⱕ14 years of age were killed in motor vehicle crashes and nearly 247 000 were injured.1In addition, black subjects of all ages are at increased risk of morbidity and death attrib-utable to motor vehicle crashes,2–4 presumably because of low rates of restraint use.5–10Although any restraint use is better than no restraint use,11,12the best protection for child passengers is a safety restraint that is appropri-ate for the age and body size of the child. Studies have demonstrated that appropriate restraint of children in-cludes the use of belt-positioning booster seats for chil-dren 4 to 8 years of age who are too big to use forward-facing car seats with internal harnesses but too small for lap and shoulder belts to fit appropriately.11,13–16Despite the demonstrated effectiveness of child safety restraint (CSR) use in reducing injury, some child pas-sengers are not restrained appropriately. Passenger re-straint laws have been shown to improve the use of seat belts.17,18Therefore, the State of Tennessee implemented enhanced CSR legislation in July 2004, which added a specific requirement for booster seat use for 4- to 8-year-old passengers, with a $50 fine for noncompliance. Few studies have evaluated the effect of enhanced CSR leg-islation on appropriate booster seat use, and few studies have included large numbers of black child passengers. The purpose of this study was to evaluate the appropri-ate use of CSRs among passengers 0 to 8 years of age, in 3 urban19counties in Tennessee, before and after imple-mentation of the enhanced state law.
We hypothesized that the appropriate use of booster seats would be very low before implementation and would increase modestly after implementation, given improvements seen in other restraint use in other states after implementation of similar legislation.20 We also hypothesized that booster seat use would be lower among 4- to 8-year-old black passengers, given our pre-vious work demonstrating lower rates of appropriate CSR use among black child passengers.21
METHODS
Study Design
We conducted a prospective, cross-sectional, on-site as-sessment of children 0 to 8 years of age at schools and after-school programs in 3 urban counties in Tennessee, before and 1 year after implementation of an enhanced CSR law. The assessment involved a brief driver inter-view and on-site vehicle and CSR inspection.
Assessment Development
The assessment tool was adapted from a previously val-idated traffic survey produced by the National Safe Kids Campaign,22 a national nonprofit organization with a focus on prevention of childhood injuries. Information
for this modified assessment tool was selected on the basis of published literature on CSR use nationally.15,23–25 Data collected included observed information (driver seat belt use, seating positions of child passengers, and CSR type) and self-reported information (race of chil-dren and driver, gender of chilchil-dren, and age, weight, and height of children in vehicle). Drivers of vehicles with passengers 4 to 8 years of age who were not restrained in a booster seat were asked to identify barriers to booster seat use, from a list of barriers chosen from the litera-ture, namely, driver did not know the child needed one, child was too large for a booster seat, child would not stay in the booster seat, booster seat cost too much, and other.24,26–29 Each assessment required ⬃2 minutes to complete.
Sample Selection
Schools and after-school programs were selected ran-domly from each study county by using a sampling scheme designed to ensure adequate distribution of in-come levels in the sample. US Census Bureau data were used to divide each county into quartiles on the basis of median household incomes.30 From the list of schools and after-school programs located within each income quartile in a county, sites were selected at random and invited to participate. Principals and directors of selected sites were contacted for permission to conduct the study at that site; all agreed to participate. At least 50 obser-vations were obtained per income quartile in each study county. Postlaw assessments were conducted at the same sites as the prelaw assessments and included greater numbers of children, to allow comparisons ac-cording to race for a separate analysis. The sample size was chosen to provide 90% power to detect a 15% difference in CSR use after implementation, with a 2-sided2test and an␣value of .05.
Data Collection
Study coordinators for each county were provided with copies of the assessment tool, written instructions with scripted questions, and photographs of various CSR types. Each study assessor completed a practice assess-ment before data collection. In addition, at least 1 certi-fied child passenger safety technician was present at each site, to provide oversight and assistance in identi-fying CSR types. Study personnel remained the same during the prelaw and postlaw portions of this study.
declined to participate. Approximately 80% of drivers approached agreed to participate. Data collection took place in April to June 2004 (before implementation) and March to May 2005 (after implementation).
Analysis
Assessment data were double-entered into Microsoft Ac-cess (Microsoft, Redmond, WA). Analyses were per-formed by using Stata 7.0 (Stata Corp, College Station, TX). Appropriate use of CSRs was determined by using the following criteria from Tennessee law: ⬍1 year or
⬍20 lb, rear-facing CSR in the rear seat of the vehicle with the harness fastened; ⬎1 year and 20 to 40 lb, forward-facing CSR in the rear seat of the vehicle with the harness fastened; and 4 to 8 years, 40 to 80 lb, and
⬍57 inches, belt-positioning booster seat in the rear seat of the vehicle with the lap/shoulder belt fastened.31 Therefore, a 10-month-old child would be counted as appropriately restrained only if he or she was in a rear-facing infant seat in the rear seat of the vehicle (if a rear seat was available), with the harness fastened. Other variables included age group (⬍4 years or 4 – 8 years), child race (white, black, or other), driver restraint use, income quartile, and study year. Child race was used for stratified analyses; in 98% of cases, the driver and pas-senger races were the same.
Multivariate Poisson regression analysis was used to model appropriate CSR use. Generalized estimating equations accounted for clustering of children according to vehicle. Changes in knowledge of the enhanced re-straint law and differences in barriers to booster seat use were determined by using 2-sided2tests. Approval for the study was obtained from the institutional review board of Vanderbilt University Medical Center before implementation.
RESULTS
Data were collected for 1247 children, 0 to 8 years of age, who were transported by 1191 drivers at 34 assess-ment sites. The age, race, and income distributions of participating children were similar before and after im-plementation (Table 1). Most drivers (before implemen-tation: 80%; after implemenimplemen-tation: 78%;P⫽.34) were restrained.
After implementation of the enhanced CSR law, the proportion of children ⬍4 years of age who were re-strained appropriately did not change significantly (be-fore implementation: 84%; after implementation: 72%; rate ratio: 0.89; 95% confidence interval: 0.79 –1.01). For the age group targeted by the enhanced law, namely, 4- to 8-year-old children, there was a significant increase in the proportion of appropriately restrained children. The proportion of 4- to 8-year-old children restrained appropriately before and after implementa-tion increased from 29% to 39% (rate ratio: 1.38; 95% confidence interval: 1.12–1.71), with controlling for
child race, income quartile, driver restraint use, study year, and clustering of children according to vehicle. The proportion of 4- to 8-year-old children using any type of restraint did not change from the prelaw period to the postlaw period (before implementation: 82%; after im-plementation: 80%; P ⫽ .49). The majority of 4- to 8-year-old children who were not restrained appropri-ately in booster seats had been placed prematurely in seat belts (before implementation: 66%; after imple-mentation: 58%).
Stratified analyses according to race for 4- to 8-year-old children are shown in Fig 1. Although there was a significant improvement in booster seat use among white children (rate ratio: 1.49; 95% confidence inter-val: 1.13–1.95), the increase in booster seat use among black children was not statistically significant (rate ratio: 1.31; 95% confidence interval: 0.93–1.87). For all time periods, booster seat use was lower among black chil-dren than white chilchil-dren. In addition, the proportion of 4- to 8-year-old black children who were unrestrained was approximately twofold greater than that of white children, both before implementation (27% and 11%,
TABLE 1 Characteristics of Children Participating in CSR Assessments Before and After Implementation of the Enhanced Restraint Law
Variable No. (%)
Before Implementation
(N⫽415)
After Implementation
(N⫽832)
Age group
⬍4 y 119 (29) 214 (26)
4–8 y 296 (71) 618 (74)
Race
White 228 (55) 356 (43)
Black 175 (42) 403 (48)
Other 12 (3) 73 (9)
Lowest income quartile 121 (29) 240 (29)
Driver restrained 398 (80) 793 (78)
FIGURE 1
respectively;P⬍.0001) and after implementation (29% and 12%, respectively;P⬍.0001).
Knowledge of the enhanced state law requiring booster seat use increased significantly after implemen-tation. Seventy-nine percent of drivers of 4- to 8-year-old passengers reported awareness of the enhanced CSR law at the postlaw assessment, compared with only 35% of drivers who cited awareness of the enhanced law before its implementation (P ⬍ .001). The majority of drivers (53%) reported learning about the enhanced law from television. Eleven percent of drivers of 4- to 8-year-old black children and none of the drivers of 4- to 8-year-old white children who were not in booster seats cited the cost of a booster seat as a barrier to use (P⫽
.05). The majority (65%) of drivers of 4- to 8-year-old white children cited other reasons for lack of booster seat use.
DISCUSSION
This study found statistically significant increases in driver knowledge of the Tennessee enhanced CSR law and in appropriate booster seat use among 4- to 8-year-old children, the target age group. These findings suggest that the law and surrounding public awareness efforts were effective and should have significant public health impact. Much of the increased use among 4- to 8-year-old children represented a switching of children from an inappropriate restraint (seat belt) to an age-appropriate booster seat, with no change in the proportion of 4- to 8-year-old children who were unrestrained. Unfortu-nately, 4- to 8-year-old black children were twice as likely as 4- to 8-year-old white children to be unre-strained, during both study periods. In addition, appro-priate restraint use among infants and toddlers⬍4 years of age did not increase.
Our data suggest that enhancing an existing CSR law with specific requirements for booster seat use can be effective in increasing use in the targeted population. Possible explanations for the increase in booster seat use include the presence of the law itself, as well as increased public awareness of the need for booster seats. In studies of adults, it has been demonstrated that the presence of a law in and of itself is a significant determinant of seat belt use.17,18,32In addition, almost 80% of drivers in our postlaw survey were aware of the law, and they cited television most commonly as the source of their infor-mation. Although we cannot differentiate the effects of the enhanced law and surrounding publicity and educa-tional campaign, the increase in booster seat use among children 4 to 8 years of age is an important public health achievement.
We were struck by the finding that there was no increase in CSR use among passengers⬍4 years of age in our study. For younger child passengers, Tennessee has had a restraint law in place for almost 20 years. There-fore, rates of restraint use for this population are much
higher than those for the older age groups. We hypoth-esize that the proportion of drivers who fail to restrain infants and toddlers appropriately may be unlikely to respond to the same types of interventions that were successful among drivers of older children. Although the use of booster seats increased,⬍50% of 4- to 8-year-old children were restrained appropriately after implemen-tation of the law. Interventions to improve the use of appropriate restraints in this age group will continue to be important.
We were surprised by the persistence and size of the disparity in unrestraint rates between black and white passengers 4 to 8 years of age, particularly in light of a recent study that demonstrated that restraint laws have reduced the disparity in seat belt use between black and white drivers.33It is possible that the black population in our sample was composed primarily of “late adopters,” or persons who are unlikely to change behavior early and without persuasion through interpersonal chan-nels.34New strategies to persuade drivers of the benefits of booster seat use, using trusted community sources for message delivery, will be required to change behavior in this population.
Our results are comparable to previous studies eval-uating the effects of booster seat laws. A study of CSR use in 6 states showed that 82% of 4- to 8-year-old children were in some form of restraint,35similar to our results. Appropriate booster seat use in a national sample of 4- to 8-year-old children was reported to be 21%,36 comparable to our prelaw results. The previous studies were from different geographic regions and included smaller proportions of black children, compared with our study. Few published data are available describing changes in appropriate restraint use among 4- to 8-year-old children after implementation of a law requiring booster seat use, especially among black children.
who were primarily parents. Some evidence exists that parents’ knowledge of their child’s weight correlates strongly with the child’s actual weight in medical records.37
CONCLUSIONS
An enhanced state law requiring booster seats for 4- to 8-year-old children can be effective in increasing booster seat use in the targeted population. Awareness of the law seems to be an important component of compliance. However, 1 year after implementation of the enhanced law, a large proportion of 4- to 8-year-old children were not restrained appropriately. Targeting specific popula-tions at risk for lower restraint use, including black chil-dren and chilchil-dren whose drivers fail to use CSRs of any kind, will be important in the future.
ACKNOWLEDGMENTS
We thank Safe Kids Coalitions in Chattanooga and Memphis, Tennessee, and Washington, DC, for assis-tance with data collection and use of the data collection tool. Special thanks go to the assessors and study partic-ipants who shared their time because of their commit-ment to improving the safety of children.
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DOI: 10.1542/peds.2006-1876
2007;119;e131
Pediatrics
Veronica L. Gunn, Rhonda M. Phillippi and William O. Cooper
Improvement in Booster Seat Use in Tennessee
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