THE COST-EFFECTIVENESS OF AIR BAGS BY SEATING POSITION

Context.-Motor vehicle crashes continue to cause significant mortality and morbidity in the United States. Installation of air bags in new p assenger vehicles is a major initiative in the field of injury prevent ion. Objective.-To assess the net health consequences and cost-effecti veness of driver's side and front passenger air bags from a societal p erspective, taking into account the increased risk to children who occ upy the front passenger seat and the diminished effectiveness for olde r adults. Design.-A deterministic state transition model tracked a hyp othetical cohort of new vehicles over a 20-year period for 3 strategie s: (1) installation of safety belts, (2) installation of driver's side air bags in addition to safety belts, and (3) installation of front p assenger air bags in addition to safety belts and driver's side air ba gs. Changes in health outcomes, valued in terms of quality-adjusted li fe-years (QALYs) and costs (in 1993 dollars), were projected following the recommendations of the Panel on Cost-effectiveness in Health and Medicine. Participants.-US population-based and convenience sample dat a were used. Main Outcome Measure.-Incremental cost-effectiveness rati os. Results.-Safety belts are cost saving, even at 50% use. The additi on of driver's side air bags to safety belts results in net health ben efits at an incremental cost of $24 000 per QALY saved. The further ad dition of front passenger air bags results in an incremental net benef it at a higher incremental cost of $61 000 per QALY saved. Results wer e sensitive to the unit cost of air bag systems, their effectiveness, baseline fatality rates, the ratio of injuries to fatalities, and the real discount rate. Conclusions.-Both air bag systems save life-years at costs that are comparable to many medical and public health practic es. Immediate steps can be taken to enhance the cost-effectiveness of front passenger air bags, such as moving children to the rear seat.