Association of BMI, mortality, points of impact and crash test ratings for drivers involved in fatal motor vehicle crashes

Introduction: Previous studies have reported a positive association between body mass index (BMI) and mortality in motor vehicle crashes. This study extends these findings by examining the effect of BMI specific to drivers controlling for crash and vehicle characteristics including vehicle safety ratings.

Methods: NHTSA’s Fatality Analysis Reporting System (FARS) data was used to identify 120,809 drivers aged 14 years and older involved in a fatal crash between the years 2010-2013. BMI was analyzed as 5 categories: underweight(<18.5); normal weight(18.5-24.9; slightly overweight(25.0-29.9); obese(30.0-34.9); and severely obese(≥35). Logistic regression models were used to examine the relationship of driver BMI and mortality across vehicle model years, specific points of crash impact and with vehicle safety ratings. Front/ front same side non-rollover crashes were assessed in subpopulation analysis. Odds ratios (OR) are reported with 95% confidence intervals (CI).

Results: In multivariable analysis, controlling for age, gender, height, BMI, restraint use, air bag deployment status, model year, vehicle type, crash type and speed-related, compared to normal weight drivers, all other categories had higher mortality with OR:1.18(1.04,1.32) in underweight, 1.05(1.01,1.09) in overweight, 1.15(1.09,1.22) in obese and 1.47(1.37,1.57) in severely obese drivers. Seatbelt use, newer vehicles and type of vehicle were highly protective. In subpopulation analysis with vehicle safety ratings, compared to poorly rated vehicles, vehicles rated good were seen to be protective with OR:0.75(0.67,0.83).

 

Conclusions: BMI of drivers, seatbelt use, vehicle manufacture model years, points of impact and crash safety ratings were important predictors of mortality in motor vehicle crashes.