June 2, 2000
Do automatic shoulder seatbelts provide a false sense of security?
[Embargoed until 1 p.m. PDT, June 6, 2000]
Drivers and passengers who rely on automatic shoulder belts risk serious injury if they fail to use their lap belts at the same time, according to a study by physicians at Harborview Medical Center to be published in the June 7 issue of the Journal of the American Medical Association.
While the use of automatic shoulder belts with lap belts reduces the risk of death in crashes by up to 86 percent, the protection afforded by a shoulder belt alone is significantly weaker. Use of automatic belts without lap belts is also associated with an increased risk of serious chest and abdominal injury.
More than 27 million vehicles have been manufactured with automatic two-point belt systems since 1987. Various studies have shown that drivers in these vehicles don?t use their manual lap belts between 50 and 71 percent of the time.
“Our research suggests a definite need to educate drivers and passengers of vehicles with automatic belt systems,” explains Dr. Frederick Rivara, a University of Washington (UW) professor of pediatrics, director of the Harborview Injury Prevention and Research Center and principal investigator in the study. “Too many of them have been killed or seriously injured due to a false sense of security.”
The researchers examined data from 25,811 crashes during the years 1993-1996. In all types of crashes, users of automatic shoulder belts without lap belts had a risk of head injury that was not significantly different from those who rode with no safety belts at all. The risks for chest and abdominal injury were actually greater for those who used automatic shoulder belts and no lap belts than for those who wore no belts at all.
“Seat belts, when properly used, make a dramatic difference in reducing the injuries and death caused by car crashes,” Rivara says. “Unfortunately, the safety margin is drastically reduced–and often entirely lost–when a driver or passenger rides with an automatic shoulder belt and an unclasped lap belt.”
In addition to Rivara, the study was written by Dr. Thomas Koepsell, UW professor of epidemiology; Dr. David Grossman, UW associate professor of pediatrics; and Dr. Charles Mock, UW assistant professor of surgery.
