Newswise — The risks of riding with an impaired driver or being involved in a crash caused by another person’s drinking are lower in countries that have comprehensive penalties for driving under the influence, according to an international study in Alcoholism: Clinical & Experimental Research. Previous research on the effects of drunk-driving policies has focused on aggregate outcomes such as accident rates or fatalities involving alcohol-impaired drivers. Relatively slight attention has been paid to harms caused by another driver’s impairment, although these “secondhand” effects are widespread and serious; in the US in 2015, almost 40 percent of drunk-driving deaths were of victims other than the impaired driver. Investigators explored whether national policies relating to drink-driving, and regional drinking cultures, were associated with such effects.

Researchers drew on more than 29,500 survey responses from 12 countries at varying stages of development and representing diverse drinking cultures: Australia, Chile, Denmark, India, Ireland, Laos, New Zealand, Nigeria, Sri Lanka, Thailand, the US, and Vietnam. Survey respondents were asked whether in the last 12 months they’d been a passenger of a drunk driver or been involved in an accident caused by an impaired driver. The survey data were compared to national alcohol policy information from the World Health Organization. This covered the stringency of blood alcohol content (BAC) limits, and the existence or otherwise of random breath testing, sobriety check points, and comprehensive penalties for drunk driving (community service, ignition interlocks, license suspension, mandatory alcohol use treatment, vehicle impoundment, and penalty points). Investigators also considered alcohol taxation variables: value added tax (VAT) rate and excise taxes. In addition, they factored in regional drinking culture, demographic characteristics, and the survey respondents’ own self-reported risky drinking. They used statistical analysis to look for associations between these factors and the secondhand effects of impaired driving at the same point in time.

The analysis found compelling evidence that comprehensive penalties for drunk driving were associated with reduced risk of being the passenger of an impaired driver and of experiencing a car crash caused by someone else’s drunk driving. The risks of these outcomes were also raised by individual factors; being male or younger, and one’s own risky drinking. The likelihood of riding with an impaired driver was lower in countries that had random breath testing and sobriety checkpoints, and/or higher VAT rates on alcohol. Survey respondents who lived in regions of high-risk drinking cultures were more likely to ride with drivers under the influence, and those who were married or cohabiting less likely. These influences were not associated with alcohol-related accidents, however, possibly because the 12-month timeframe limited relevant outcomes.

The researchers endorse comprehensive penalties for drunk driving as a potentially effective approach to mitigating its secondhand harms; random breath testing and sobriety check points also show promise. They recommend more attention be paid to strategies that modify social norms relating to drinking. The study findings are associational, a basis for future research into cause.

Are countries’ drink-driving policies associated with harms involving another driver’s impairment? T. Greenfield, W. Cook, K. Karriker-Jaffe, L. Li, R. Room (pp xxx).

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