22 February 2019 In Drinking & Driving

BACKGROUND: Drink driving is an important risk factor for road traffic accidents (RTAs), which cause high levels of morbidity and mortality globally. Lowering the permitted blood alcohol concentration (BAC) for drivers is a common public health intervention that is enacted in countries and jurisdictions across the world. In Scotland, on Dec 5, 2014, the BAC limit for drivers was reduced from 0.08 g/dL to 0.05 g/dL. We therefore aimed to evaluate the effects of this change on RTAs and alcohol consumption.

METHODS: In this natural experiment, we used an observational, comparative interrupted time-series design by use of data on RTAs and alcohol consumption in Scotland (the interventional group) and England and Wales (the control group). We obtained weekly counts of RTAs from police accident records and we estimated weekly off-trade (eg, in supermarkets and convenience stores) and 4-weekly on-trade (eg, in bars and restaurants) alcohol consumption from market research data. We also used data from automated traffic counters as denominators to calculate RTA rates. We estimated the effect of the intervention on RTAs by use of negative binomial panel regression and on alcohol consumption outcomes by use of seasonal autoregressive integrated moving average models. Our primary outcome was weekly rates of RTAs in Scotland, England, and Wales. This study is registered with ISRCTN, number ISRCTN38602189.

FINDINGS: We assessed the weekly rate of RTAs and alcohol consumption between Jan 1, 2013, and Dec 31, 2016, before and after the BAC limit came into effect on Dec 5, 2014. After the reduction in BAC limits for drivers in Scotland, we found no significant change in weekly RTA rates after adjustment for seasonality and underlying temporal trend (rate ratio 1.01, 95% CI 0.94-1.08; p=0.77) or after adjustment for seasonality, the underlying temporal trend, and the driver characteristics of age, sex, and socioeconomic deprivation (1.00, 0.96-1.06; p=0.73). Relative to RTAs in England and Wales, where the reduction in BAC limit for drivers did not occur, we found a 7% increase in weekly RTA rates in Scotland after this reduction in BAC limit for drivers (1.07, 1.02-1.13; p=0.007 in the fully-adjusted model). Similar findings were observed for serious or fatal RTAs and single-vehicle night-time RTAs. The change in legislation in Scotland was associated with no change in alcohol consumption, measured by per-capita off-trade sales (-0.3%, -1.7 to 1.1; p=0.71), but a 0.7% decrease in alcohol consumption measured by per-capita on-trade sales (-0.7%, -0.8 to -0.5; p<0.0001).

INTERPRETATION: Lowering the driving BAC limit to 0.05 g/dL from 0.08 g/dL in Scotland was not associated with a reduction in RTAs, but this change was associated with a small reduction in per-capita alcohol consumption from on-trade alcohol sales. One plausible explanation is that the legislative change was not suitably enforced-for example with random breath testing measures. Our findings suggest that changing the legal BAC limit for drivers in isolation does not improve RTA outcomes. These findings have significant policy implications internationally as several countries and jurisdictions consider a similar reduction in the BAC limit for drivers.

FUNDING: National Institute for Health Research Public Health Research Programme.

01 February 2017 In Drinking & Eating Patterns

BACKGROUND: Alcohol contributes to approximately 30% of all serious crashes. While the majority of drivers acknowledge the risks associated with drink-driving, a significant proportion of the population continue to engage in this behaviour. Attitudes towards drink-driving as well as personal alcohol consumption patterns are likely to underpin a driver's decision to drink-drive. These associations were explored in the current study.

METHODS: A large (N=2994) cross-sectional online survey of a representative sample of drivers in Australia was conducted. Participants provided information about their own alcohol consumption patterns, drink-driving behaviour as well as attitudes towards drink-driving (own and others) and enforcement strategies.

RESULTS: Alcohol consumption patterns differed according to age, gender and work status. Drivers who reported drink-driving behaviour and had high risk alcohol consumption patterns were less likely to agree that drink-driving leads to increased crash risk and more likely to agree they drink and drive when they believed they could get away with it. In contrast, drivers who did not report drink-driving and had low risk consumption patterns were more likely to report that the enforcement strategies are too lenient. Binary logistic regression showed that high risk alcohol consumption patterns and agreement from drivers that they drink and drive when they believe they can get away with it had the strongest associations with drink-driving. These findings highlight the relationships between one's drinking patterns, drink-drive behaviour and attitudes towards drink-driving and drink-driving enforcement.

CONCLUSIONS AND IMPLICATIONS: The patterns of associations that emerged suggest that drink-driving is the expression of a broader health issue for the most "at-risk" cohort of drinkers. The decision to drink and drive may result from a need borne from an alcohol dependent lifestyle exacerbated by a social acceptability of the behaviour and positive attitudes towards one's ability to drink-drive with few adverse consequences. Therefore, the broader alcohol consumption patterns of drink-drivers needs to be considered when targeting drink-drive reductions.

OBJECTIVE: To explore whether early age of drinking onset is prospectively associated with respondents unintentionally injuring themselves and others when respondents were under the influence of alcohol, controlling for current alcohol dependence/abuse, frequency of consuming 5 drinks per occasion, and other demographic characteristics.

METHODS: From 2001 to 2002, in-person interviews were conducted with a national multistage probability sample of 43,093 adults aged 18 years older. From 2004 to 2005, of 39,959 eligible respondents, 34,653 were reinterviewed. The cumulative 2-survey response rate was 70.2%. Respondents were asked the age at which they first started drinking (not counting tastes or sips), diagnostic questions for alcohol dependence and abuse, questions about behaviors that increase risk of injury, and whether respondents, when under the influence of alcohol, injured themselves or someone else as a driver in a motor vehicle crash or in some other way.

RESULTS: Logistic regression analyses revealed that the younger respondents were when they started drinking, the greater the likelihood that, between the 2 surveys, they experienced alcohol dependence/abuse, drank 5 drinks per occasion at least weekly drove under the influence of alcohol, and placed themselves in situation after drinking where they could be hurt. After controlling for those injury risk and sociodemographic characteristics, respondents who began drinking at earlier ages remained more likely between the 2 surveys to have, under the influence of alcohol, unintentionally injured themselves and someone else. More than one third of those injuries occurred when respondents 25 years of age were under the influence, although only 7% of respondents were 25 years of age. Persons other than respondents experienced 20% of those unintentional injuries, more than one third of them in traffic.

CONCLUSION: Delaying drinking onset may help reduce unintentional alcohol-related injuries that drinkers may inflict on themselves and others.

The Amethyst Initiative, signed by more than 100 college presidents and other higher education officials calls for a reexamination of the minimum legal drinking age in the United States. A central argument of the initiative is that the U.S. minimum legal drinking age policy results in more dangerous drinking than would occur if the legal drinking age were lower. A companion organization called Choose Responsibility explicitly proposes "a series of changes that will allow 18-20 year-olds to purchase, possess and consume alcoholic beverages." Does the age-21 drinking limit in the United States reduce alcohol consumption by young adults and its harms, or as the signatories of the Amethyst Initiative contend, is it "not working"? In this paper, we summarize a large and compelling body of empirical evidence which shows that one of the central claims of the signatories of the Amethyst Initiative is incorrect: setting the minimum legal drinking age at 21 clearly reduces alcohol consumption and its major harms. We use a panel fixed effects approach and a regression discontinuity approach to estimate the effects of the minimum legal drinking age on mortality, and we also discuss what is known about the relationship between the minimum legal drinking age and other adverse outcomes such as nonfatal injury and crime. We document the effect of the minimum legal drinking age on alcohol consumption and estimate the costs of adverse alcohol-related events on a per-drink basis. Finally we consider implications for the correct choice of a minimum legal drinking age.

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