To determine 1) whether state booster seat laws are effective on a national scale in decreasing rates of motor vehicle related fatalities and incapacitating injuries in children 4-6 years old, and 2) the extent to which proper booster seat use is associated with decreased rates of fatalities and injuries in 4-8 year old children.
This was a retrospective, longitudinal analysis of all motor vehicle occupant crashes involving children 4- 8 years old identified in the Fatality Analysis Reporting System from January 1999 through December 2009. Rates of fatalities and incapacitating injuries were compared in states before and after booster seat legislation. We performed a negative binomial regression model clustered on individual states and adjusted for state highway speed limit, maximum legal blood alcohol limit, adult fatality and incapacitating injury rates, and median household income. We used the chi-square test to compares rates of fatalities and injuries between children 4-8 years properly restrained and those with improper or no booster seat use.
9,848 fatalities and incapacitating injuries occurred in children 4-8 years old from 1/99-12/09. State-level statistics on year of booster seat legislation, total number of fatalities and incapacitating injuries in children 4- 6 years, and fatality rates per 100,000 children aged 4-6 years from 1999-2009 are included in Figure 1. The adjusted incidence rate ratio of death or injuries was 0.82 (95% confidence interval [CI], 0.73-0.91) after passing booster seat laws for 4-6 year olds, and it was 0.67 (95% CI 0.56,-0.80) for 7-8 year olds. An increased odds of injury were seen in children with lap/shoulder belt use only [4-6 years: Adjusted odds ratio (AOR) 1.2, 95% CI 1.1-1.3; 7-8 years: AOR 1.7, 95% CI, 1.2-2.4)] and children with no/improper restraint (4-6 years: AOR 2.0, 95% CI 1.8,-2.1; 7-8 years: AOR 4.2, 95% CI, 3.0-5.8) compared to children with proper booster seat use.
In the United States, booster seat laws are associated with decreased fatalities and incapacitating injuries in children 4-8 years with further protection gained from proper use.