Fewer Opioid Deaths Found in States with Legal Medical Marijuana
States permitting the use of medical marijuana have found decreases in opioid overdose deaths and use of opioids for chronic pain.
A recent report found that between 1999 and 2010, states that permitted medical marijuana use had an average of about 25% fewer opioid overdose deaths each year compared with those states where cannabis remained illegal.
Another report revealed that patients who frequented a medical marijuana dispensary reported cutting their opioid use by more than half in treating their chronic pain.
Report 1: State Comparisons
The first study was conducted at the Center for Health Equity Research and Promotion at the Philadelphia Veterans Affairs Medical Center. Other author affiliations included the University of Pennsylvania; the Montefiore Medical Center, Bronx, New York; and the Johns Hopkins Bloomberg School of Public Health, Baltimore. The report can be accessed at:
Bachhuber, MA, et al. “Medical cannabis laws and opioid analgesic overdose mortality in the United States, 1999-2010.” JAMA Intern Med 2014; 174(10):1668-1673.
The study objective was to determine the association between the presence of state medical cannabis laws and opioid analgesic overdose mortality. According to the authors, opioid analgesic overdose mortality continues to rise in the United States, driven by increases in prescribing for chronic pain. Because chronic pain is a major indication for medical cannabis, laws that establish access to medical cannabis may change overdose mortality related to opioid analgesics in those states.
The opioid analgesic overdose mortality rate in each of the 50 states from 1999 to 2010 was retrieved using the Wide-ranging Online Data for Epidemiological Research (WONDER) interface to access multiple cause-of-death data from the Centers for Disease Control and Prevention (CDC). After capturing data on overdose deaths in which an opioid analgesic was involved, the authors then determined the association between medical cannabis laws and opioid analgesic-related deaths using linear time regression models. The main outcome was age-adjusted opioid analgesics overdose death rate per 100,000 population in each state. The mean independent variable of interest was the presence of medical cannabis laws.
Three states (California, Oregon, Washington) had medical cannabis laws prior to 1999. Ten states (Alaska, Colorado, Hawaii, Maine, Michigan, Montana, Nevada, New Mexico, Rhode Island, and Vermont) enacted medical cannabis laws between 1999 and 2010.
- States with medical cannabis laws had a 24.8% lower mean annual opioid overdose mortality rate compared with states without medical cannabis laws.
- Examination of the association between medical cannabis laws and opioid analgesic overdose mortality in each year after implementation of the law showed that such laws were associated with a lower rate of overdose mortality that generally strengthened over time:
- Year One after legalization of medical cannabis showed a 19.9% reduction in opioid overdose deaths.
- Year Two: 25.2% reduction
- Year Three: 23.6% reduction
- Year Four: 20.2% reduction
- Year Five: 33.7% reduction
- Year Six: 33.3% reduction.
This study found that states with medical cannabis laws had lower mean opioid analgesic overdose mortality rates compared with states without such laws. Since those findings persisted when excluding intentional overdose deaths due to suicide, this suggested that medical cannabis laws are associated with lower opioid analgesic overdose mortality among individuals using opioids for medical purposes.
The majority of all opioid analgesic overdoses occur among patients who have legitimate prescriptions from a single provider. In those states with enacted medical cannabis laws, patients with chronic noncancer pain, who would have otherwise initiated opioid therapy, may choose medical cannabis instead. In addition, those patients already receiving opioid analgesics who start medical cannabis treatment may experience improved analgesia, thus electing to decrease their opioid use, which in turn, decreases their dose-dependent risk of overdose. Further medical cannabis laws could lead to decreases in polypharmacy, particularly with benzodiazepines, in people taking opioid analgesics, thus further reducing the overdose risk.
The authors commented that if the relationship between medical cannabis laws and opioid analgesic overdose mortality is confirmed in additional studies, enactment of laws to allow for use of medical cannabis may be advocated as part of a comprehensive program of policies to reduce the population risk of opioid analgesics.
Report 2: Patient Patterns of Use
The study was performed at the University of Michigan Medical School in Ann Arbor with the aim of examining whether using medical cannabis for chronic pain changed individual patterns of opioid use. It can be accessed at:
Boenke, KF, et al. “Medical cannabis use is associated with decreased opiate medication use in a retrospective cross-sectional survey of patients with chronic pain.” The Journal of Pain 2016; 17: 739-744.
The study was designed as a survey distribution carried out in collaboration with owners of a local medical cannabis dispensary in Ann Arbor, Michigan. Dispensary owners helped recruit registered medical cannabis patients to take an online questionnaire. The authors conducted the retrospective survey of 244 medical cannabis patients with chronic pain who patronized the cannabis dispensary between November 2013 and February 2015. The survey contained 46 questions, detailing the following:
- Medical conditions for which cannabis was used
- Method/frequency of cannabis use
- Changes in non-cannabis medication use
- Changes in medication side effects
- Quality of life changes since starting cannabis use
- Demographic information
Medical cannabis cardholders in Michigan must receive a certification from a licensed physician that they have a medical condition deemed by statute to justify cannabis use. The authors hypothesized that many cannabis users were using cannabis for chronic pain reduction as a substitute for opioids.
- As mentioned above, 244 of the participants used cannabis to treat chronic pain. Since some questionnaires were incomplete, only complete questionnaires of participants with chronic pain were included in analysis. Those numbered 185.
- Most participants (78.9%) smoked cannabis daily.
- Of those 185 participants who completed questionnaires, the mean change in self-reported opioid use after initiation of cannabis was a decrease in opioid use by 64%.
- 45% of the chronic pain participants said they had a positive change in their quality of life after initiating cannabis.
- There were comparable reductions in self-reported usage of many other classes of analgesic drugs (i.e., nonsteroidal anti-inflammatory drugs, disease-modifying anti-rheumatic drugs).
- The mean number of medication classes used also decreased significantly in all respondents before and after cannabis use: mean of 2.38 medication classes before cannabis use; mean of 1.81 medication classes after cannabis use. The reported medication drug classes, in addition to the analgesics mentioned above, included antidepressants, selective serotonin reuptake inhibitors, and selective serotonin-norepinephrine reuptake inhibitors.
- Side effects of medication on everyday functioning decreased after cannabis use. On a scale from 1 (no effect) to 10 (significant effect), the mean values were 6.51 before cannabis use and 2.79 after cannabis use.
Since the initiation of medical cannabis use, chronic pain patients reported significant reductions in opioid use. Also they reported significant decreases in medication side effects that impacted their daily functioning (including those from opioids), decreases in total number of medications taken, and improvement in quality of life. The authors concluded that the study provides intriguing hints of the value of cannabis as an effective pain medication and as an effective agent against opioid overuse and overdose.
They cautioned, however, against using this study to change clinical practice toward cannabis until more robust studies are completed to confirm and support these findings.
Richard L. Wynn, BS Pharm, PhD, is professor of pharmacology at the Baltimore College of Dental Surgery, Dental School, University of Maryland Baltimore.
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