Seatbelts significantly reduce the risk of death in motor vehicle accidents, but a certain number of individuals from some subgroups tend not to wear their seatbelts.

In this study, we hypothesized that obese drivers (in fatal crashes) were less likely to wear seatbelts than their normal-weight counterparts.

A retrospective study was conducted on the drivers in motor vehicle crashes entered into the Fatality Analysis Reporting System database between 2003 and 2009. A number of precrash variables were found to be significantly associated with seatbelt use. These were entered into a multivariate logistic regression model using stepwise selection. Drivers were grouped into weight categories based on the World Health Organization definitions of obesity by body mass index. Seatbelt use was then examined by body mass index, adjusted for precrash variables that were significantly associated with seatbelt use.

The odds of seatbelt use for normal-weight individuals were found to be 67% higher than the odds of seatbelt use in the morbidly obese. The relationship of seatbelt use between the different weight groups and the morbidly obese is as follows (odds ratios [ORs] for each comparison are listed with 95% confidence limits [CL]): underweight vs morbidly obese (OR, 1.62; CL, 1.47-1.79), normal weight vs morbidly obese (OR, 1.67; CL, 1.54-1.81), overweight vs morbidly obese (OR, 1.60; CL, 1.48-1.74), slightly obese vs morbidly obese (OR, 1.40; CL, 1.29-1.52), and moderately obese vs morbidly obese (OR, 1.24; CL, 1.13-1.36).

Seatbelt use is significantly less likely in obese individuals compared with their normal-weight counterparts.