摘要：Objectives. To assess the association between medical marijuana laws (MMLs) and the odds of a positive opioid test, an indicator for prior use. Methods. We analyzed 1999–2013 Fatality Analysis Reporting System (FARS) data from 18 states that tested for alcohol and other drugs in at least 80% of drivers who died within 1 hour of crashing (n = 68 394). Within-state and between-state comparisons assessed opioid positivity among drivers crashing in states with an operational MML (i.e., allowances for home cultivation or active dispensaries) versus drivers crashing in states before a future MML was operational. Results. State-specific estimates indicated a reduction in opioid positivity for most states after implementation of an operational MML, although none of these estimates were significant. When we combined states, we observed no significant overall association (odds ratio [OR] = 0.79; 95% confidence interval [CI] = 0.61, 1.03). However, age-stratified analyses indicated a significant reduction in opioid positivity for drivers aged 21 to 40 years (OR = 0.50; 95% CI = 0.37, 0.67; interaction P < .001). Conclusions. Operational MMLs are associated with reductions in opioid positivity among 21- to 40-year-old fatally injured drivers and may reduce opioid use and overdose. In 1996, California Proposition 215, a voter-initiated medical marijuana law (MML), received 55.6% of the popular vote and became law. Proposition 215 provided criminal protections for patients as well as defined caregivers, who in turn could cultivate the marijuana that physicians could now recommend. 1 Since then, 22 additional states and the District of Columbia have enacted their own MMLs, either by voter initiative or through state legislation. Of these laws, the MMLs in Connecticut, Maine, Massachusetts, Minnesota, New York, and the District of Columbia are the only ones that do not allow marijuana to be recommended or authorized for severe or chronic pain, 2 and they tend to be more medically oriented and restrictive. 3 In the United States, nonmalignant chronic pain afflicts a growing proportion of adults. 4 The prescription of opioids for the treatment of this type of pain has also increased. 5,6 However, despite the legitimate benefits conferred by these drugs, the potential for harm has caused some concern, 7,8 perhaps because of large increases in opioid use disorders 9,10 and opioid overdoses 11,12 observed within the last 2 decades. Furthermore, recent policies aimed at reducing the supply of opioid prescriptions (e.g., prescription drug monitoring programs) may have also inadvertently led to recent increases in heroin overdoses. 13 Alternatives for the treatment of chronic pain are clearly needed. 14 Marijuana may offer a substitute to opioids in many states with MMLs. 15,16 Unfortunately, data on treatment efficacy is limited, in large part because of current federal scheduling. Regardless, severe or chronic pain is among the most common indications cited by medical marijuana patients. 17 In theory, we would expect the adverse consequences of opioid use to decrease over time in states where medical marijuana use is legal, as individuals substitute marijuana for opioids. In a recent study of MMLs and opioid overdoses, 18 state MMLs were associated with reductions in the annual rate of state-level opioid overdoses. The relationship between MMLs and other indicators of opioid use or adverse consequences needs to be further examined, as this relationship potentially identifies actionable points of intervention on a growing opioid epidemic (e.g., expanding eligible medical conditions for marijuana to include chronic pain). One such indicator is the prevalence of opioid use. Although opioid use can be difficult to measure, tested opioid positivity in blood or urine is objective, and it provides a clear indicator of any prior opioid use, for medical or recreational purposes. Although we know of no representative general population data with tested opioid positivity among living participants, toxicological tests for substances among drivers fatally injured in car crashes represents a potential data source. Repeated annual panels of drivers killed in crashes in states with and without MMLs are available; in some states, data are uniformly collected for the majority of deceased drivers. Furthermore, states that do not have an MML but eventually pass one are more similar to states in which an MML has already been passed, reducing the possibility of bias in comparing MML and non-MML states. 19 Thus, our aim was to empirically assess whether, among drivers who died within 1 hour of a traffic collision, crashing in a state with an MML was associated with a reduced likelihood of opioid positivity compared with crashing in a state that would eventually pass an MML but had not yet done so.
