The Effect of Cannabis Laws on Access to Pain Medications among Commercially Insured Patients in the United States

Abstract

Chronic pain is a major trigger for opioid prescribing in the U.S. Further, 35 U.S. states and the District of Columbia have adopted medical cannabis laws (MCLs), and chronic pain is the most common condition qualifying for medical cannabis access. Little is known about how legal access to medical cannabis has changed prescribing patterns for commercially insured Americans. In this article, we estimate a series of state-by-state synthetic control case-studies (29 cases, across 22 states in two policy levers for which observable pre-and post- policy timeframe comply with our eligibility criteria), using data from a nationwide comprehensive commercial claims database with approximately 15 – 20 million patients per year. We assess changes in patterns of opioid analgesic and non-opioid pain medications dispensed, capturing both intensive and extensive margins. The methodology allows us to construct a stable counterfactual in the pre-policy period for each case and to accommodate heterogeneity across treated units and their treatment timing. In all except two of the 22 examined states we find reductions in the rate of patients receiving any dispensed prescriptions of opioids (extensive margin) following the implementation of an MCL, the majority of which are statistically significant at conventional levels. We also find a marginally significant reduction in the intensive margin, measured as both the average daily supply of dispensed prescriptions and as the average number of dispensed prescriptions per patient. When we focus on other non-opioid pain medications, we do not find such a clear pattern, with very few significant effects emerging following the introduction of MCLs.

Our study highlights the large variation in positive spillovers of MCLs on prescription opioid utilization among commercially insured Americans across U.S. states. Findings suggest that cannabis may offer an alternative for pain management with opioid analgesics. Thus, policymakers should consider MCLs as an alternative tool for pain management, specifically when other policies that constrain supply of opioids might push some Americans to more harmful substances.