A new study looking at data from a federally funded survey found that the prevalence of medical cannabis use more than doubled in the United States between 2013 and 2020, driven largely by state-level legalization.
The National Survey on Drug Use and Health, which has been conducted annually since 1971, added a question about medical marijuana in 2013, specifically asking whether any cannabis use within the past 12 months was recommended by a doctor. During the first year, 1.2 percent of respondents answered affirmatively. Seven years later, that figure had risen to 2.5 percent.
Authors of the study, Greg Rhee and Robert Rosenheck, both affiliated with the Yale School of Medicine’s psychiatry department and the U.S. Department of Veterans Affairs (VA) New England Mental Illness, Research, Education and Clinical Center, calculated that the proportion of Americans using medical marijuana during the seven-year period grew at an average rate of 12.9 percent each year.
“This study documents a continued nationwide increase in use of cannabis for diverse medical purposes between 2013 and 2020,” they write in the paper, published this week as a pre-proof for the American Journal of Preventive Medicine. “Living in a state that legalized medical cannabis remained significantly associated with greater odds of medical cannabis use.”
Other variables highlighted by the report as having significant associations with medical marijuana use included being aged 18 to 25, being male, never having married, having completed some college education and being uninsured.
Such associations, however, do not mean those groups were more likely to have used medical cannabis, nor did they necessarily see greater increases in prevalence of use over the seven-year study period. The observed associations only mean those groups’ trends over time were the most statistically significant interactions with survey years.
In terms of health insurance status, for example, the prevalence of medical marijuana use among uninsured people actually increased the slowest over the seven-year timeframe compared to other groups, including those on private insurance, Medicaid, Medicare or “other.” But the change over time was the least likely to be due to chance.
“When the ‘uninsured’ is interacted with the ‘time’ (survey years), the effect is actually smaller and was significant,” Rhee explained in an email to Marijuana Moment.
Rhee said the study doesn’t attempt to describe how state-level transitions from medical-only legalization laws to broader adult-use legalization may have affected medical marijuana use. “Unfortunately, it’s outside the scope of analysis because we were not able to distinguish states by legalization status,” he said.
The study also analyzed medical marijuana use by respondents who said they experienced certain medical conditions. “Clinically relevant subgroups that experienced significantly greater odds of medical cannabis use included: poorer self-rated health statuses, past-year major depressive episode, cocaine use disorder, and use of non-prescription pain relievers (p<0.01 for each),” it says.
Authors write that “the association of medical cannabis use with depression, cocaine use disorder, and non-medical use of pain relievers suggests it may have either been prescribed for those conditions or used on patient initiative for these problems,” although they acknowledge the national survey data does not provide enough information to draw those conclusions.
The study repeatedly points to a lack of conclusive health data on the risks and benefits of cannabis—a takeaway Rhee also emphasized to Marijuana Moment.
“Medical cannabis is increasingly used,” he said. “But, long-term medical benefits and harms are not clearly known for multiple medical conditions. Future studies are needed to weigh between effectiveness and safety of medical cannabis.”
The study claims that cannabis “does not generally lead to overdose deaths (in contrast to opioids)” although “several unintended consequences (e.g., developing psychosis and motor vehicle crashes) have been documented.”
Medical marijuana use notwithstanding, federal data published last month showed that overall past-month cannabis use by U.S. teens hit a record low since 2011.
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