Prescription Opioid Misuse: What Do Medical Marijuana Laws Have to Do With It?

Researchers at Columbia Mailman School of Public Health report almost no change in nonmedical prescription opioid use or opioid use disorder after states enacted medical marijuana laws. Overall, opioid use disorder among prescription opioid users decreased slightly after the passage of the laws. Until this study, there had been little research on medical marijuana laws’ effects on the use of other substances (i.e., alcohol, opioids)—particularly, prescription opioid use misuse, and opioid use disorder. The findings are published online in JAMA Network Open.

“Studies on medical marijuana laws and their effects on prescription opioid use are scarce and are limited by measuring opioid use indirectly and among groups, not individuals,” said Luis Segura, MD, MPH, a doctoral student at Columbia Mailman School, Department of Epidemiology, and first author. “When comparing the overall effect of use after versus before medical marijuana laws were passed, we found small increases in nonmedical use of prescription opioids and slight decreases or no change in prescription opioid use disorder among nonmedical users of prescription opioids—even for states that allowed dispensaries.”

The researchers used the National Survey on Drug Use and Health, an annual survey of approximately 70,000 individuals aged 12 years and older, from 2004 to 2014, to investigate the association between living in a state with medical marijuana laws and individual-level opioid use and prescription opioid use disorder among nonmedical prescription opioid users. They also analyzed whether these outcomes varied by age and racial or ethnic groups.

The results differed from earlier studies that found decreases in nonmedical opioid use, opioid prescribing and opioid overdoses post-medical marijuana law enactment. There are a number of potential reasons for this finding, according to the researchers.

“Other studies that found an inverse association between medical marijuana enactment and opioid-outcomes did not measure opioid-outcomes for individuals,” observed Silvia Martins, MD, PhD, associate professor of epidemiology, and senior author. The hypothesis generated from these studies is that after medical marijuana law enactment, health care professionals would be more likely to prescribe medical marijuana instead of opioid medications, this, in turn, would reduce the chance of individuals to misuse prescription opioids and develop consequences. We tested this relationship and found no evidence that the passage of medical marijuana laws—even in states with dispensaries—was associated with a decrease in individual opioid use of prescription opioids for nonmedical purposes.”

“Our findings may suggest that medical marijuana policies could be insufficient to reduce individual-level opioid outcomes and that opioid-specific approaches and policy interventions such as prescription drug monitoring programs, and laws on prescribing practices are needed,” said Martins.

Co-authors are Christine Mauro, Natalie Levy, Nicole Khauli, Morgan Philbin, and Pia Mauro, all of Columbia Mailman School.

The study was supported by National Institute on Drug Abuse (DA039804A, DA045224, DA037866).