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In the United States (US), legalization of medical cannabis on a statewide basis was associated with a nearly 30% decrease in schedule III (but not schedule II) opioid prescription numbers and dosages for Medicaid patients, according to a study published in Addiction.
Given the simultaneous expansion of cannabis legalization and worsening of the US opioid crisis, investigators sought to explore the association between legalization and opioid prescriptions in states that have legalized cannabis for medical use. While evidence suggests that cannabis may offer pain relief, correlations between legalization and opioid use has yet to be fully examined.
Researchers performed a secondary analysis of state-level prescription records using information collected between 1993 and 2014 via Medicaid State Drug Utilization Data from fee-for-service Medicaid patients. Primary outcomes were the number and dosage of opioid prescriptions, and Medicaid spending on opioid prescriptions. Statewide legalization status of medical cannabis was also examined. Multivariable linear regression adjusted for confounders was used to analyze the relationship between medical cannabis legalization and opioid prescriptions.
Overall, Schedule II opioids were prescribed more frequently than Schedule III drugs, with higher prescription rates in states without cannabis legalization. States with legalized medical cannabis saw a significant reduction in prescription numbers (29.6%; 95% CI, 2.4%-56.7%; P =.03) and dosages (29.9%; 95% CI, 4.8%-55.0%; P =.02) of Schedule III medications (primarily codeine), as well as reductions in Medicaid opioid spending (28.8%; 95% CI, 1.4%-56.1%; P =.04). No associations were identified between medical cannabis legalization and Schedule II medications (primarily hydrocodone and oxycodone).
After controlling for legalization, no relationship was established between medical dispensary permits and schedule II or III prescriptions. No associations were identified between schedule II or III opioids and decriminalization, recreational legalization, or statewide Prescription Drug Monitoring Programs. Had all US states enacted legalization by 2014, investigators estimated Medicaid savings from reduced opioid prescriptions at $17.8 million. However, because schedule III prescriptions represented less than 5% of Medicaid opioid spending, the impact of these results in terms of overall spending was thought to be limited.
Study limitations included a lack of insight into individual patient responses to policy changes and uncertainty regarding generalizability to managed care patients, emergency department/inpatient populations, the entire US population, or other countries.
“The findings of this study added to the still limited literature, supporting the hypothesis that statewide medical cannabis legalization in the US was associated with reduced opioids received by Medicaid enrollees,” concluded the authors. They recommended that future investigations examine individual level data to discern causation and attempt to replicate their results in other countries.
Reference
Liang D, Bao Y, Wallace M, Grant I, Shi Y. Medical cannabis legalization and opioid prescriptions: evidence on US Medicaid enrollees during 1993-2014 [published online July 10, 2018]. Addiction. doi:10.1111/add.14382
