ORIGIN: Community Guide systematic review
Publication Date: 12/07/2009
The operation of motor vehicles while intoxicated is a major public health problem. Each year in the United States roughly 13,400 people die and an additional 255,500 are injured in motor vehicle crashes involving an alcohol-impaired driver. In 2006, these crashes accounted for almost a third of all U.S. traffic-related deaths. CDC: Impaired Driving Factsheet.
Blood alcohol per se laws set a blood alcohol limit at which an individual is considered legally impaired (i.e., impairment is “per se” because actual inability to function need not be established). Currently, all states set their BAC limit at 0.08 percent; some previously set the BAC levels at 0.10 percent. For examples of BAC per se laws, see Cal. Veh. Code §23152 (California), Fla. Stat. §316.193 (Florida), K.S.A. §8-1567 (Kansas), M.R.S. §2411 (Maine), N.M. Stat. Ann. §66-8-102 (New Hampshire), N.M. Stat. Ann. §66-8-102 (New Mexico), N.C. Gen. Stat. §20-138.1 (North Carolina), O.R.S. 813.010 (Oregon), Utah Code §41-6a-502 (Utah), 23 V.S.A. §1201 (Vermont), and Va. Code Ann. §18.2-266 (Virginia).
In a Community Guide systematic review, Shults et al. reviewed nine studies that examined the impact of lowering the BAC limit to 0.08 percent on the rate of alcohol-related motor-vehicle deaths. Shults, et al. Reviews of Evidence Regarding Interventions to Reduce Alcohol-Impaired Driving. Am J Prev Med. 2001;21(4S):66-88. According to the reviewers, the underlying studies reveal a considerable association between the adoption of 0.08 percent BAC laws and a decline in alcohol-related motor-vehicle deaths; the median reduction in motor vehicle fatalities after the laws were adopted was 7 percent. Shults et al view these studies as strong evidence of the effectiveness of 0.08 BAC laws as a public health intervention. However, they caution that most of the BAC laws analyzed were enacted along with, or were supplemented by, other preventive drunk-driving laws, such as Administrative License Revocation (ALR) laws, making it difficult to isolate the exact magnitude of the impact of BAC laws.
ORIGIN: Peer-reviewed meta-analysis; Community Guide
Publication Date: 12/07/2009
The operation of motor vehicles while intoxicated is a major public health problem. Each year in the United States roughly 13,400 people die and an additional 255,500 are injured in motor vehicle crashes involving an alcohol-impaired driver. In 2006, these crashes accounted for almost a third of all U.S. traffic-related deaths. Drivers age 16 to 20 who engage in drunk driving pose an especially dangerous risk to themselves and other motorists. CDC: Impaired Driving Factsheet.
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).
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 indentified 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 Community Guide provides online access to a table summarizing the results of each study it reviewed.
Additional Resources: The Community Guide