Passage of child restraint laws depends on information that supports the effectiveness of restraints in motor vehicle crashes. Effectiveness estimates often are based on data from the National Highway Traffic Safety Administration Fatality Analysis Reporting System (FARS), a database of fatal crashes. However, use of these data alone may lead to an underestimation of restraint benefits because it assumes that children who survive fatal crashes have similar restraint use to that of children in nonfatal crashes. The National Automotive Sampling System Crashworthiness Data System (NASS CDS) provides a cross-section analysis of two-way crashes but only includes a low number of child fatalities. Elliott and associates combined data from these databases to compare how child restraint systems (i.e., rear-facing and forward-facing car seats, and shield and belt-positioning booster seats) reduce childhood crash fatalities compared with seat belts alone.

The FARS data included details of automotive crashes with at least one fatality that occurred on a public traffic way in the United States or Puerto Rico and in which vehicles could not be driven away from the crash site. The NASS CDS data sampled non-fatal crashes from police reports of crashes in which at least one vehicle could not be driven. Data were limited to those involving a child of two to six years of age who was restrained by a child restraint system or a seat belt. The main outcome measure was death of a child passenger from injuries resulting from the crash.

There were 1,096 children included in the FARS data who were killed in a crash between 1998 and 2003, and 1,433 children included in the NASS CDS sample. Children who were in appropriately used child restraints had a 28 percent reduction in the risk of death compared with those in seat belts, after the authors adjusted for vehicle type, model year, seating position, driver and passenger ages, and driver survival status (relative risk = 0.72, 95% confidence interval, 0.54 to 0.97). When the analysis included cases involving significant misuse of child restraints (i.e., unattached restraints or no use of harness), there was still a 21 percent reduction of death risk with restraint systems compared with seat belts.

The authors conclude that child restraint systems are effective in reducing deaths and serious injuries from motor vehicle crashes in children two to six years of age. They add that the use of child restraint systems needs to be promoted through improvement of child restraint laws and through education and disbursement programs.