Obesity Increases Risk of Death in Severe Vehicle Crashes

Published January 11, 2011

Obese drivers face an increased risk of dying during a severe auto accident, according to research by Dietrich Jehle, MD, UB professor of emergency medicine.

A moderately obese driver faces a 21 percent increased risk of death, while the morbidly obese driver faces a 56 percent increased risk.
—Findings from research conducted by Dietrich Jehle, MD
UB professor of emergency medicine

In a study posted online ahead of print in the American Journal of Emergency Medicine, Jehle and colleagues found that a moderately obese driver faces a 21 percent increased risk of death, while the morbidly obese driver faces a 56 percent increased risk.

Interestingly, underweight and normal weight drivers were found to be at higher risk of dying from a severe crash than the slightly overweight. The results suggest that having a little bit of extra padding provides a cushioning effect during a crash.

“The severity and patterns of crash injuries depend on a complex interaction of biomechanical factors, including deceleration velocity at impact, seat belt and air bag use, vehicle type and weight, and type of impact, but the effect of body mass on crash outcome has not been previously evaluated in databases of adequate size or controlled for some of these confounding factors,” says Jehle, first author on the study.

 Based on this data, Jehle suggests several changes that might save lives.

“Extending the range of adjustable seats would be helpful, as well as encouraging moderately and morbidly obese individuals to buy larger vehicles with more space between the seat and the steering column,” he says.

Jehle also recommends that vehicle manufacturers design and test interiors with obese crash-test dummies, which are currently not available, in addition to testing with average weight crash-test dummies.

 “Crash test dummies have saved lives and provided invaluable data on how human bodies react to crashes, but they are designed to represent normal-weight individuals. If they represented our overweight American society, there could be further improvements in vehicle design that could decrease mortality,” he says.

 For underweight and normal weight individuals, placing airbags within the seat belt also might be protective, Jehle adds.

 To investigate the relationship between driver body size and risk of crash-related fatality, Jehle and colleagues analyzed data in the national Fatality Analysis Reporting System database (FARS).

 Drivers were grouped based on body mass index into underweight, normal, overweight, slightly obese, moderately obese and morbidly obese categories.

Severe crashes between 2000 and 2005 that involved one or two vehicles (cars, pickups, SUVs or vans) were used in the analysis. Fatalities considered related to the crash that occurred within 30 days of the crash, such as those resulting from surgery, also were included.

In addition to the overall results, data analyzed by sex show that in the moderately and morbidly obese categories, both male and female drivers independently demonstrated a statistically significant increase in death when compared with normal-weight drivers.

Seth Gemme, a third-year UB medical student, is corresponding author on the paper. Christopher Jehle, a student at Miami University of Ohio, contributed to the study during a UB summer research program.

 The research is funded in part by a grant from the Federal Highway Administration.