What should I say to parents of children four to eight years of age regarding booster seats in cars?

Abstract

There is clear evidence that booster seats reduce motor vehicle-related injuries among children four to eight years of age (1,2). Despite this fact, booster seats are currently underused in this population. Evidence from controlled studies shows that a variety of interventions will increase parental use of booster seats. Interventions that include more than one tactic (ie, a combination of education and incentives, or a combination of education and distribution of a free booster seat) may be the most effective. The Canadian Paediatric Society recommends that children weighing between 18 kg and 36 kg (between 40 lbs and 80 lbs), and having a height of less than 145 cm (57 inches), or are eight years of age or younger, should use a booster seat and be placed in the back seat of a vehicle (3). Booster seats improve seat belt fit among children by elevating them off the seat and allowing the seat belt to lie across the pelvis, and ribcage and shoulder, rather than the stomach and neck. Abdominal viscus injury, abdominal bruising and fractured vertebrae, that occur among children not using a booster seat, are collectively known as ‘lap-belt syndrome’, and refer to any injury in which the improperly fitting seat belt has actually injured the child in lieu of protecting him or her (4). Among children, nonuse and misuse of age-appropriate child restraints are common factors associated with motor vehicle-related morbidity and mortality (5). Booster seats can reduce the risk of injury in a motor vehicle collision by up to 59% (6). Compared with children who are appropriately restrained in booster seats, those restrained by a seat belt alone are at 3.5 times the risk of injury and 4.2 times the risk of head trauma (7,8). A study (9) between 1998 and 2002, examining motor vehicle collisions involving children four to seven years of age from Wisconsin, USA, showed that 16 of the 28 observed deaths, and 84 of the 144 hospitalizations would have been prevented if the children were using booster seats at the time of the collisions (9). While similar statistics are not available for Canada, self-reported booster seat use among Canadians was found to be 28% (10); approximately 400 Canadian children are killed or hospitalized with a serious injury each year due to a motor vehicle collision (unpublished data). Between 1994 and 2000, hospital admissions have decreased by 40% to 50% among children zero to four years of age, and 10 to 14 years of age, but only declined by 18% in children five to nine years of age (unpublished data). Current research demonstrates that the prevalence of booster seat use is low. Often, children are incorrectly placed in a seat belt when they are too young. In 1997, Decina and Knoebel (11) found that 75% of preschool-aged children were restrained only by a seat belt. Winston et al (12) examined four years of restraint patterns among children younger than nine years of age who were in a collision in one of 15 American states. Between 1998 and 2002, the use of booster seats increased from 3.8% to 8.9% among children four to eight years of age. Among children four to eight years of age from Michigan, USA, only 194 of 3420 children were restrained in a booster seat and 1255 children were unrestrained (5). The age of the driver and his or her own seat belt were the strongest predictors of booster seat use. When asked about booster seat use among their four- to eight-year-old children, parents in Michigan stated that their primary motivation to use booster seats was safety (13). Reasons for nonuse included lack of enforcement, perceived inconvenience, refusal by the child, parents believed that their child was too big and lack of knowledge regarding the safety benefits derived from using a booster seat. Parents reported that mandatory booster seat legislation would increase the likelihood of booster seat use. Simpson et al (14) conducted focus groups in an effort to determine strategies to increase booster seat use. Parents identified media campaigns, legislation, education and the requirement of older children to use restraints as potential methods to increase booster seat use (14).