Restraint Systems Confirmed Safer than Seat Belts for Kids

PHILADELPHIA, June 5 ? As anticipated, young children were better protected from death in car crashes by child safety seats than by seat belts, according to researchers here.

Compared with seat belts, properly used child safety seats reduced children's risk of death by nearly 30%, reported Flaura K. Winston, M.D., Ph.D., and colleagues, of Children's Hospital of Philadelphia in the June issue of the Archives of Pediatric & Adolescent Medicine.

Results of some previous seatbelt versus safety seat studies have been mixed, failing to adequately control for the severity of the crash, the investigators said. A better study was required because U.S. child safety seat laws still need improvement, they added.

The current study included data on more than 9,000 children from the ages of two through six involved in a crash between 1998 and 2003. To better control for crash severity, only two-way auto accidents in which one car was "rendered undrivable" were included.

Data were obtained from the U.S. Department of Transportation Fatality Analysis Reporting System (FARS) and the National Automotive Sampling System Crashworthiness Data System (NASS CDS).

Roughly half the children studied were in safety seats and roughly half in seat belts. About one in 1,000 children in the study died (0.11%).

Compared with seat belts, safety seats were associated with a 28% reduced risk of death (relative risk=0.72; 95% confidence interval=0.54 to 0.97) when both were properly used.

When including cases in which seat belts and safety seats were seriously misused-for example, when two children were buckled with one seat belt or when the safety seat harness was not used-safety seats still reduced mortality risk by 21% compared with seat belts (RR=0.79; 95% CI=0.59 to 1.05).

The study included rear-facing safety seats, forward-facing safety seats, and belt-positioning booster seats.

"Child restraint systems offer a considerable safety advantage over seat belts alone for biomechanical reasons," the authors said. "Child restraint systems are designed to reduce risk for ejection during a crash, better distribute the load of the crash through structurally stronger bones rather than soft tissues, limit the crash forces experienced by the vehicle occupant by prolonging the time of deceleration, and potentially limit the contact of the occupant with intruding vehicle structures."

"Based on our current findings as well as the long-standing biomechanical evidence for child-restraint effectiveness and previous demonstrations of the importance of child restraint systems in reducing nonfatal injury risk, efforts should continue to promote child restraint use through improved child restraint laws and with education and disbursement programs," they concluded.

Although all states have child-passenger safety laws, many of these laws are not adequate, according to the National Highway Traffic Safety Administration (NHTSA).

For example, as of January 2006, only 33 States and the District of Columbia had provisions requiring an appropriate restraint device or booster seat for children who have outgrown their child safety seats but are too small for the adult safety belt, the NHTSA said.

Key recommendations from the American Academy of Pediatrics on child safety seats and seat belt use include:

• All infants should ride in a rear-facing safety seat until they have reached at least one year of age and weigh at least 20 pounds.

• Once children have reached this age and weight, they can ride in forward-facing safety seats. However, it is best for children to ride in rear-facing seats until they reach the highest weight or height limit allowed by the particular brand of seat.

• Children are ready for a belt-positioning booster seat when one of the following is true: 1) they reach the top weight or height allowed for their safety seat, 2) their shoulders are above the harness slots, or 3) their ears have reached the top of the seat.

• Children should stay in a booster seat until the adult seat belt fits correctly (the lap belt lies low across the thighs and the shoulder belt crosses the middle of the chest and shoulder.) This is usually when the child reaches about 4' 9" in height and is between eight and 12 years of age.

The authors noted a potential limitation of the study involving a possible confounding between a child-restraint system use and crash severity, leading to either upward or downward bias in the estimate of child restraint system effectiveness.

They wrote that "for example, if drivers who restrain their children in child-restraint systems are less likely to be involved in potentially fatal crashes (i.e., those fatal with the child in either a child-restraint system or a seat belt, in a child restraint system only, or in a seat belt only), use of the NASS CDS population may overstate the effectiveness of child restraint systems versus seat belts by confounding child-restraint use with safer driving behavior."

The study was supported by the State Farm Mutual Automobile Insurance Company.