The Problem: The operation of motor vehicles while intoxicated is a major public health problem. In 2016, roughly 10,500 people died in motor vehicle crashes involving an alcohol-impaired driver, accounting for nearly one-third of all traffic related deaths. CDC: Impaired Driving Factsheet. Approximately 6,500 (62%) of these individuals had a blood alcohol content (BAC) level of 0.08 g/dL or higher. The remaining fatalities consisted of passengers (29%) and non-passengers (9%). Alcohol-Impaired Driving. Teen drivers a 3 times more likely than experienced drivers to suffer from a fatal crash. CDC: Teen Drinking and Driving
The Law: All U.S. states currently set the minimum legal drinking age at 21 years (MLDA21). Federal legislation withholds federal highway funds from states that do not adopt an MLDA of 21 years (23 U.S.C. § 158). For examples of MLDA21 laws, see TX Alcoholic Beverage Code § 106.04 (Texas), Conn. Gen. Stat. 30-1(12) and Conn. Gen. Stat. §30-89(Connecticut).
The Evidence: Two independent systematic reviews of the relevant studies of this intervention have found a robust association between raising the MLDA to 21 and reductions in alcohol-related crashes. In a Community Guide systematic review, Shults et al. reviewed 33 studies that examined the effect of MLDA21 on fatal and nonfatal crashes likely to have involved alcohol. Shults, et al. Reviews of Evidence Regarding Interventions to Reduce Alcohol-Impaired Driving. Am J Prev Med. 2001;21(4S):66-88. Seventeen of the underlying studies evaluated the impact of raising the MLDA to 21, 11 evaluated laws that lowered the MLDA, and remaining 18 used regression analysis to measure changes in both directions. The review found a median reduction in alcohol-related crashes of 17 percent associated with raising the MLDA and a median increase of 8 percent in alcohol-related crashes associated with lowering the MLDA.
Wagenaar and Toomey reviewed 48 studies that measured the impact of MLDA21 on alcohol consumption and reviewed 57 studies that measured the impact of MLDA21 on alcohol-related crashes. Wagenaar, Toomey. Effects of Minimum Drinking age Laws: Review and Analyses of the Literature from 1960 to 2000. Journal of Studies on Alcohol. 2002(14 Suppl):206-25. Across the 48 studies, the authors identified 27 measures finding a statistically significant inverse relationship between MLDA21 and alcohol consumption (8 found a statistically insignificant inverse relationship; 5 found a positive relationship). Some of the measures included, for example, self-reported alcohol consumption and sale of particular alcoholic beverages. Fifty-two measures were identified finding a statistically significant inverse relation between MLDA21 and crashes (12 found a statistically insignificant inverse relationship; 2 found a positive relationship). These measures included a broad range of types of injuries and crashes outcomes (e.g., nighttime fatal crashes, alcohol-related crashes).
The Evidence: A 2013 meta-analysis sought to evaluate the effectiveness of minimum legal drinking age laws in reducing alcohol-related harm. Population-level interventions to reduce alcohol-related harm: An overview of systematic reviews. Authors included 52 articles from relevant databases whothat met the inclusion criteria of review at the population level, systematic methodology. Publications must have investigated interventions focused on alcohol-related harm reduction between 2002-2012. Authors found that higher MLDA led to significantly reduced alcohol consumption and prevalence of alcohol-related crashes.
The Bottom Line: According to the authors of a peer-reviewed systematic study, there is strong evidence to support the effectiveness of MLDA21 as an intervention aimed at reducing alcohol consumption and alcohol -involved motor vehicle crashes.
Additional Information: The Community Guide provides online access to a table summarizing the results of each study it reviewed.
Impact: Effective