Delta V, principal direction of force, and restraint use contributions to motor vehicle crash mortality

To measure the combined contribution of change in velocity (Deltav), principal direction of force (PDOF), and restraint use on mortality after vehicular trauma.

The Crash Injury Research and Engineering Network population includes patients <8 years old with one injury with an Abbreviated Injury Scale score >or=3 or with two injuries with an Abbreviated Injury Scale score >or=2, who were occupants of a vehicle. Patients 15 years or younger; in rear collisions; back seat occupants; in crashes with Deltav >80 km/h, unknown Deltav, or unknown PDOF; or in vehicles without airbags were excluded. Mortality was analyzed in relation to Deltav (km/h), restraint use, and PDOF using chi2. Multiple logistic regression models were built, including possible confounders (body mass index, age, gender) and interactions were explored. An [alpha] = 0.05 was used for all statistics.

A total of 1,261 cases were included. Mortality was higher for unrestrained than for restrained patients (17% vs. 9%) and was higher for lateral than for frontal impact patients (17% vs. 11%). Higher mortality rates were also observed for Deltav 40-80 km/h than for Deltav <40 km/h (17% vs. 9%). Multiple logistic regression findings, after adjusting for age, gender, and body mass index, revealed significant effects of lateral PDOF (odds ratio [OR] 3.06 [2.03-4.61]), unrestrained status (OR 2.95 [2.01-4.38]), and Deltav 40-80 km/h (OR 3.65 [2.44-5.44]). Effect modification was found between PDOF and Deltav.

A Deltav 40 km/h to 80 km/h, lack of restraint use, and lateral impact significantly affects mortality. A synergistic effect was found between Deltav 40-80 km/h and lateral PDOF.