Pollini Robin A, Romano Eduardo, Johnson Mark B, Lacey John H
Pacific Institute for Research and Evaluation, 11720 Beltsville Drive, Suite 900, Beltsville, MD 20705, United States.
Drug Alcohol Depend. 2015 May 1;150:135-40. doi: 10.1016/j.drugalcdep.2015.02.024. Epub 2015 Mar 1.
The liberalization of marijuana laws has led to concerns that such changes will increase "drugged driving" and crash-related mortality. California decriminalized marijuana effective January 1, 2011; we examine the impact of this change on marijuana-involved driving.
We used laboratory testing from roadside surveys and the Fatality Analysis Reporting System (FARS) to assess impacts on weekend nighttime drivers and fatally injured drivers, respectively. We calculated marijuana prevalence (measured by laboratory-confirmed delta-9-tetrahydrocannabinol [THC] in roadside surveys and cannabinoids in FARS) and compared corresponding 95% confidence intervals (CI) to identify statistically significant changes post-decriminalization. We also conducted multiple logistic regression analyses to determine whether the odds of marijuana-involved driving increased significantly after controlling for potential confounders.
There was no statistically significant change in the prevalence of THC-positive driving among weekend nighttime drivers (n=894) in 2012 (9.2%; 95% CI: 6.3, 12.2) compared to 2010 (11.3%; 95% CI: 8.5, 14.0) or in the adjusted odds of testing positive for THC (adjusted odds ratio [AOR]=0.96; 95% CI: 0.57, 1.60). In contrast, we found a statistically significant increase in the prevalence of cannabinoids among fatally injured drivers in 2012 (17.8%; 95% CI: 14.6, 20.9) compared to the pre-decriminalization period 2008-2010 (11.8%; 95% CI: 10.3, 13.3). The adjusted odds of testing positive for cannabinoids were also significantly higher in 2012 (AOR=1.67; 95% CI: 1.28, 2.18).
Our study generated discrepant findings regarding the impact of decriminalization on marijuana-involved driving in California. Factors that may have contributed to these findings, particularly methodological factors, are discussed.
大麻法律的放宽引发了人们对这些变化会增加“毒驾”及与撞车相关死亡率的担忧。加利福尼亚州自2011年1月1日起将大麻合法化；我们研究了这一变化对涉及大麻驾驶的影响。
我们利用路边调查的实验室检测结果以及死亡分析报告系统（FARS），分别评估对周末夜间驾驶者和致命伤驾驶者的影响。我们计算了大麻流行率（通过路边调查中实验室确认的δ-9-四氢大麻酚[THC]以及FARS中的大麻素进行测量），并比较相应的95%置信区间（CI），以确定合法化后具有统计学意义的变化。我们还进行了多项逻辑回归分析，以确定在控制潜在混杂因素后，涉及大麻驾驶的几率是否显著增加。
与2010年（11.3%；95%CI：8.5，14.0）相比，2012年周末夜间驾驶者（n = 894）中THC阳性驾驶的流行率没有统计学意义上的变化（9.2%；95%CI：6.3，12.2），THC检测呈阳性的校正几率也无变化（校正优势比[AOR]=0.96；95%CI：0.57，1.60）。相比之下，我们发现与2008 - 2010年合法化前时期（11.8%；95%CI：10.3，13.3）相比，2012年致命伤驾驶者中大麻素的流行率有统计学意义的增加（17.8%；95%CI：14.6，20.9）。2012年大麻素检测呈阳性的校正几率也显著更高（AOR = 1.67；95%CI：1.28，2.18）。
我们的研究得出了关于加利福尼亚州大麻合法化对涉及大麻驾驶影响的不一致结果。讨论了可能导致这些结果的因素，特别是方法学因素。
