Analysis of fatalities in extended cab pickup trucks using an estimating equation method.

We compared the fatality risk for occupants of rear passenger seats in extended cab and crew cab pickup trucks to the fatality risk for front seat occupants of the same vehicles using the (US) Fatality Analysis Reporting System (FARS) for 1982-1997. A 10-digit truncated vehicle identification number was used to classify the pickup trucks. The data were analyzed with an estimating equation for data having few observations per stratum. We identified 549 extended cab pickup trucks with one or more occupants of rear passenger seats and one or more occupant deaths. Occupants of rear passenger seats had a fatality risk 43% lower than front seat occupants (95% confidence interval 32% to 52%), controlling for age, sex, and restraint use. Occupants of rear seats of extended cabs in compact pickup trucks did not experience any higher fatality risk (relative to front-seat occupants of the same vehicles) than rear seat occupants of extended cabs in full-size pickup trucks and large 4-door crew cabs.