Several recent ecological and cross-sectional studies have suggested that states with medical marijuana laws have both decreased prescription drug use (medical and non-medical) and decreased harms, including overdose, compared with states without medical marijuana laws. Although these studies have generated press, methodological concerns exist regarding the validity of inferences drawn from population-level policy data applied to individual behavior. Researchers examined individual-level data from the 2015 National Survey on Drug Use and Health to determine the association between medical marijuana use and risk of medical and nonmedical prescription drug use. Risk ratios [RR] were calculated adjusting for age, sex, race, health status, family income, and living in a state with legalized medical marijuana. Compared with those without medical marijuana use:
- Individuals with medical marijuana use had an elevated risk of self-reported prescription medication use in the past 12 months (RR, 1.62).
- Individuals with medical marijuana use were more likely to report nonmedical use of any prescription medications in the past 12 months (RR, 2.12), specifically, with elevated risks for pain relievers (RR, 1.95), stimulants (RR, 1.86), and tranquilizers (RR, 2.18).
Comments: These findings challenge the notion that medical marijuana protects against opioid-related harms. Although this study was retrospective and relied on self-report data, it should prompt clinicians to screen for polypharmacy and non-medical prescription drug use among patients with medical marijuana use.
Jeanette M. Tetrault, MD
Reference: Caputi TL and Humphreys K. Medical marijuana users are more likely to use prescription drugs medically and nonmedically. J Addict Med. 2018;12(4):295–299.