MILWAUKEE, March 3 - Obese men are more likely to suffer a fatal injury in a car crash than men of normal weight, but bean poles don't do well either, according to a study here.
Male drivers with a body-mass index (BMI) greater than 35 or lower than 22 were significantly more likely to die after front-end or left-side collisions, compared with men with intermediate BMIs, reported Shankuan Zhu, M.D., Ph.D., and colleagues at the Medical College of Wisconsin here.
Moderately overweight men (with BMIs around 28) were least likely to die, compared with their larger or skinnier counterparts, the investigators reported in an article published online by the American Journal of Public Health. The investigators cited a possible "cushioning effect."
"The increased risk of dying in motor vehicle collisions associated with a high BMI may be due to some combination of momentum effects, co-morbidities of obesity, and emergency and postoperative treatment problems in the obese," the authors speculated.
Body-mass index did not affect women's mortality risk after a crash, perhaps because gender differences in body shape lead to different injury patterns, the researchers speculated.
The study analyzed data on more than 22,000 U.S. drivers 16 or older involved in a police-reported car crash from 1997 to 2001. The data were obtained from a collection system sponsored by the U.S. Department of Transportation.
Men at the lowest end of the weight spectrum, with a BMI of 17, had about 2.5 times the risk of mortality compared with the reference BMI of 28 (P<.05 for trend), the study found.
Men at the highest end of the spectrum, with a BMI of 45, had greater than sevenfold mortality risk. Men with a BMI of 40 had about twice the risk, the researchers reported.
The trend remained significant even after adjusting for potentially confounding factors such as age, seat-belt use, and airbag deployment, the investigators said.
The findings "document another potential health risk associated with obesity among men," the authors said.
Because Americans are growing larger, as numerous studies have documented, it may be time for crash test dummies to follow suit, the authors suggested.
Current vehicle cabin designs are based on a standard crash test dummy in the driver's position with a BMI of 24.3, the authors said.
"These cabin designs may not be optimal for drivers with a different body habitus and may contribute to the higher fatality seen at both ends of the BMI continuum," the authors concluded. "Future crash dummy simulations and other studies are needed to account for individual and gender-related variations in body mass and fat distribution in tests of velocity and vehicle design."