Obese drivers are more likely to die in car wrecks than other drivers, according to a new study.
The findings raise questions about whether car safety design might need to change to accommodate the large number of Americans who are obese -- roughly a third of the population.
The study, published online Jan. 21 in the Emergency Medicine Journal, examined federal data of fatal car accidents from 1996 to 2008. Researchers from the Safe Transportation Education and Research Center at the University of California, Berkeley, looked for collisions that involved two vehicles of similar size and type and that killed one or both drivers.
Of the 3,403 pairs of drivers studied, almost half were of normal weight; about one-third were overweight; and almost one-fifth were obese.
The researchers found that the risk of death increased with the level of the driver's obesity. The study relied on World Health Organization classifications, which categorize obesity from levels I to III.
Drivers who met the criteria for level I obesity were 21 percent more likely to die; at level II they were 51 percent more likely to die; and at level III they were 80 percent more likely to die than normal-weight drivers.
The higher death rates may be due in some cases to underlying health problems, but car design might also be a factor, the researchers concluded.
"It may be the case that passenger vehicles are well designed to protect normal-weight vehicle occupants but are deficient in protecting overweight or obese occupants," they wrote.