摘要：Objectives. We estimated the injury prevention impact and cost savings associated with alcohol interlock installation in all new US vehicles. Methods. We identified fatal and nonfatal injuries associated with drinking driver vehicle crashes from the Fatality Analysis Reporting System and National Automotive Sampling System’s General Estimates System data sets (2006–2010). We derived the estimated impact of universal interlock installation using an estimate of the proportion of alcohol-related crashes that were preventable in vehicles < 1 year-old. We repeated this analysis for each subsequent year, assuming a 15-year implementation. We applied existing crash-induced injury cost metrics to approximate economic savings, and we used a sensitivity analysis to examine results with varying device effectiveness. Results. Over 15 years, 85% of crash fatalities (> 59 000) and 84% to 88% of nonfatal injuries (> 1.25 million) attributed to drinking drivers would be prevented, saving an estimated $342 billion in injury-related costs, with the greatest injury and cost benefit realized among recently legal drinking drivers. Cost savings outweighed installation costs after 3 years, with the policy remaining cost effective provided device effectiveness remained above approximately 25%. Conclusions. Alcohol interlock installation in all new vehicles is likely a cost-effective primary prevention policy that will substantially reduce alcohol-involved crash fatalities and injuries, especially among young vulnerable drivers. Despite significant reductions in the 1980s, alcohol-involved motor vehicle crashes (AI-MVCs) remain a significant public health problem. 1–3 Since 1994, even as overall fatalities from crashes have declined, AI-MVC fatalities, as a proportion of all traffic fatalities, have remained higher than 30%. 1–3 In 2011, 9878 fatalities resulted from a crash with at least 1 intoxicated driver (blood alcohol content [BAC] ≥ 0.08 g/dL). 4 AI-MVCs are also a significant economic burden to communities, with societal costs estimated to be as high as $59 billion annually, which is 21% of the total annual economic cost ($277 billion) associated with MVC-related injury. 5 Previous success reducing fatal and nonfatal injuries resulting from drink driving is largely attributable to successful enforcement of alcohol availability and alcohol-related driving laws (e.g., license suspension, minimum legal drinking age laws, 0.08 grams per deciliter BAC limits, zero tolerance laws, sobriety checkpoints), as well as the general deterrence effect conferred by impaired driving penalties. 6–9 However, these laws are difficult to enforce because they rely on police identification of impaired drivers. 3 As a result, alcohol-impaired driving arrests are rare, with estimates that an impaired driver drives an average of 80 times before being stopped for driving while intoxicated (DWI). 1,2 Even license suspension, which has previously provided the strongest evidence for reducing DWI recidivism, with reductions of impaired driver fatal crash risk by as much as 50%, 10–12 has limited impact. Previous studies have indicated that as many as 50% to 75% of offenders continue to operate a vehicle despite license suspension. 13–15 Furthermore, half of convicted DWI drivers continue to drive without a license even after they are eligible for reinstatement, citing successful evasion of police during their license suspension period. 16,17 Difficulty detecting impaired drivers has led to the development of in-vehicle technological solutions that can prevent alcohol-impaired driving, including such devices as alcohol ignition interlocks. 1 Current interlock devices are designed as an alcohol breath-testing unit connected to the ignition switch of the vehicle that prevents driving if the driver’s breath contains more than a predetermined limit of alcohol (typically BAC > 0.02 g/dL). 18–20 They are used in all 50 states for multiple DWI offenders, either as a Department of Motor Vehicles mandated condition of license reinstatement or as a component of DWI judicial sentencing. Interlocks are highly effective while installed on the vehicle, with a systematic review finding a 67% median reduction in DWI recidivism. 20–24 Limited evidence is available examining their associated impact on MVCs, but recent studies suggest that AI-MVCs may also decrease while interlocks are installed. 25–27 Despite the clear public health benefit and existence of the technology for several decades, widespread interlock use is limited. In 2013, only 300 000 interlock devices were actively in use throughout the United States, representing less than a quarter of DWI offenders. 28 Limited usage is thought to result from low DWI conviction rates, state policies restricting interlocks to repeat DWI offenders, and a preference among offenders to have their license suspended rather than install devices that prevent impaired driving. 20 The weaknesses in the current enforcement model, combined with technological improvements in interlock devices, has generated interest in interlock use as a primary prevention tool. In 2008, the National Highway Traffic Safety Administration (NHTSA) launched the Driver Alcohol Detection System for Safety (DADSS) program, a 5-year collaborative industry and government program to explore the feasibility, benefits, and public policy challenges associated with widespread use of in-vehicle alcohol detection technologies. Application of alcohol interlocks to all new vehicles is one primary prevention strategy under discussion. Literature examining interlock use as a primary prevention tool is limited. Bjerre et al 26 studied the installation of 300 interlocks in commercial vehicles (buses, taxis, trucks) in Sweden, finding that they prevented 3.4 drunk driving trips (BAC > 0.02 g/dL) for every 1000 potential car trips. 26 Lahausse and Fildes 29 modeled the injury prevention benefit associated with alcohol interlock installation in all newly registered Australian vehicles; they found that interlocks would prevent up to 24% of all fatalities and 11% of serious injuries annually. This study, however, was limited by the inability to analyze comprehensive Australian crash data, necessitating extrapolation of fatality data from a single Australian state, as well as the use of an estimated fatal-to-nonfatal injury ratio for the derivation of serious injury estimates. Furthermore, although these studies demonstrated the potential injury prevention impact of interlocks, no previous studies have analyzed fatal and nonfatal crash data to examine the primary prevention impact within the United States. Our objectives for the present study were (1) to estimate the potential impact on fatalities and nonfatal injuries of alcohol interlock installation in all new vehicles, and (2) to estimate the potential decrease in economic costs associated with injury prevention by a universal alcohol-ignition interlock policy. Such data have the potential to provide a better understanding of how the mandatory installation of alcohol interlocks in new vehicles, as proposed within the DADSS program, might contribute to reducing AI-MVC fatalities and nonfatal injuries.
