标题：Effects of the Minimum Legal Drinking Age on Alcohol-Related Health Service Use in Hospital Settings in Ontario: A Regression–Discontinuity Approach
摘要：Objectives. We assessed the impact of the minimum legal drinking age (MLDA) on hospital-based treatment for alcohol-related conditions or events in Ontario, Canada. Methods. We conducted regression–discontinuity analyses to examine MLDA effects with respect to diagnosed alcohol-related conditions. Data were derived from administrative records detailing inpatient and emergency department events in Ontario from April 2002 to March 2007. Results. Relative to youths slightly younger than the MLDA, youths just older than the MLDA exhibited increases in inpatient and emergency department events associated with alcohol-use disorders (10.8%; P = .048), assaults (7.9%; P < .001), and suicides related to alcohol (51.8%; P = .01). Among young men who had recently crossed the MLDA threshold, there was a 2.0% increase ( P = .01) in hospitalizations for injuries. Conclusions. Young adults gaining legal access to alcohol incur increases in hospital-based care for a range of serious alcohol-related conditions. Our regression–discontinuity approach can be used in future studies to assess the effects of the MLDA across different settings, and our estimates can be used to inform cost-benefit analyses across MLDA scenarios. Given that alcohol consumption contributes to a substantial burden of disability and mortality among young people, 1 most countries worldwide have implemented minimum legal drinking age (MLDA) legislation that seeks to reduce alcohol-related harm among youths by imposing age restrictions on the purchasing, possession, and consumption of alcohol. 2,3 Although a large body of work has attempted to assess the impact of MLDA laws, 2,4,5 this literature has focused primarily on assessments of patterns of alcohol consumption or motor vehicle accidents (MVAs) in the United States. As a result, the current literature likely underestimates the full impact of the MLDA on morbidity, especially alcohol-related conditions resulting in health service use in hospital settings. For example, a recent cost-effectiveness study of population-based interventions designed to reduce alcohol-related morbidity in Canada considered the effects of the MLDA only on MVAs. 6 Understanding the full role of MLDA legislation in alcohol-related harm is a critical aspect of evidence-based policies, and an earlier Canadian study we conducted showed that the MLDA has a substantial impact on inpatient hospital admissions for a range of serious alcohol-related conditions. 7 The study’s findings revealed that, relative to youths slightly younger than the MLDA, those slightly older than the MLDA exhibited significant increases in admissions for alcohol-use disorders (16%-20%; P ≤ .001) and self-inflicted injuries (9.6%; P = .03). Among young men who had recently crossed the MLDA threshold, there was a significant 4.4% increase ( P = .001) in hospitalizations for external injuries, including a 9.2% jump ( P = .02) in admissions for MVAs. However, this earlier study relied exclusively on inpatient admissions and, thus, probably captured only a small (but extremely costly) proportion of total alcohol-related health service use in hospital settings. In the present study, we addressed this limitation by examining integrated inpatient and emergency department records from Canada’s most populous province, Ontario, which has an MLDA of 19 years. Use of inpatient and emergency department records from Ontario—a setting with universal access to physician and hospital-based services—allowed us to make comprehensive, population-based estimates of alcohol-related health service use in hospital settings without the potential biases resulting from variations in patients’ medical insurance status. We used a regression-discontinuity (RD) approach 8,9 (a quasi-experimental approach that can provide credible estimates of the causal effect of an intervention on a specified outcome 10 ) in our study. The RD design allowed us to take advantage of the sharp discontinuity in the legality of alcohol purchasing and consumption occurring at the MLDA. We assigned youths who had not reached the MLDA and youths no longer subject to the MLDA to separate groups. The basic, underlying assumption of our RD approach was that, with the exception of the effect of the removal of the MLDA in the latter group, individuals slightly older than the MLDA and those slightly younger than the MLDA would be similar in terms of observed (and unobserved) characteristics. This seemed to be a reasonable assumption given the likelihood that individuals separated by only a single month in age on either side of the MLDA would have similar characteristics related to our outcome variables (other than the impact of the MLDA in the older group). Our design also assumed that all observed and unobserved variables (which might influence alcohol-related morbidity outcomes) were smoothly distributed across the age cutoff 11 and that the effects of the MLDA could be inferred if the regression line showed a discontinuity—a change in intercept—at the MLDA cutoff. 12 Another major advantage of our approach is that the results can be clearly represented by simple scatterplots showing changes in rates of the outcome variables before and after the legal drinking age. We expected significant increases in hospital-based health service use for alcohol-related conditions to appear abruptly just after the MLDA. In light of the ongoing, vigorous debate about lowering the MLDA in the United States, 13 as well as evidence-based recommendations for raising the MLDA to 21 years in Australia, 14,15 it is critical for well-supported alcohol policies to integrate a full assessment of the impact of the MLDA on alcohol-related morbidity, a neglected area in the current literature.
