The reason earlier studies have found that airbags save lives is that they used only a special subset of the available data, said Meyer. The Fatality Analysis and Reporting System (FARS) is a high-quality compilation of information about every highway accident for which a death occurred. The Crashworthiness Data System (CDS) is another high-quality dataset, containing random samples of all accidents. The previous studies used FARS, and Meyer's study used CDS.
"When we look at the random sample of all accidents, we find that airbags are associated with increased risk of death," she said, "and this increase is due to more deaths with airbags in low-speed crashes and no seatbelts. However, if we limit the dataset to include only collisions in which a fatality occurred, we get a significantly reduced risk of death due to airbags."
By way of analogy, the Meyer explained it this way: "If you look at people who have some types of cancer, you will see that those who get radiation treatment have a better chance of surviving than those who don't. However, radiation is inherently dangerous and could actually cause cancer. If you give everyone radiation treatments, whether they have cancer or not, you will probably find an increased risk of death in the general population.
"Making everyone have airbags and then verifying the effectiveness using only fatal crashes in FARS is like making everyone get radiation and then estimating the lives saved by looking only at people who have cancer. Overall, there will be more deaths if everyone is given radiation, but in the cancer subset, radiation will be effective."
The new study directly contradicts assertions about airbag safety on the NHTSA Web site, said Meyer. The correct
Contact: Mary Meyer
University of Georgia