EFFECTIVENESS OF SAFETY-BELT USE - A STUDY USING HOSPITAL-BASED DATA FOR NONFATAL MOTOR-VEHICLE CRASHES

To evaluate the effectiveness of safety-belt use in reducing the likelihood of a serious injury, we analyzed data from the Iowa Safety Restraint Assessment study collected from 893 front-seat passenger car occupants treated for nonfatal injuries in the emergency department of 16 Iowa hospitals from November 1987 through March 1988. Data analyzed included demographic information, motor-vehicle and crash-related information, and medical information collected on all driver-seat and right-front-seat occupants. Logistic regression analyses were used to assess outcomes for front-seat occupants who did or did not use safety belts, while controlling for confounder variables. The crude odds of being seriously injured (Injury Severity Score greater than or equal to 9) were greater for those who were not using safety belts than for those who were (4.4 to 1, respectively) at the time of the crash. The odds of a serious injury for people not using safety belts versus those using safety belts was greater in larger cars than in small cars. We concluded that the use of safety belts reduces the number and seriousness of injuries for cars of all sizes; however, car size may influence the effectiveness of safety-belt use in preventing a serious injury. The limitations of this study (including small sample size, the lack of detailed vehicle and crash information, and the lack of injury outcome information for all of each vehicle's passengers) underscore the need for further research into the role of vehicle size and mass in the effectiveness of safety restraint systems in nonfatal and fatal crashes or fatal combined with nonfatal crashes.