The impact of medical and recreational marijuana laws on opioid prescribing in employer-sponsored health insurance.

Using data from Truven Health MarketScan Commercial Claims and Encounters Database between 2009 and 2015, we studied the effects of medical and recreational marijuana laws on opioid prescribing in employer-sponsored health insurance. We used a differences-in-differences (DD) approach and found that the implementation of medical marijuana laws (MMLs) and recreational marijuana laws (RMLs) reduced morphine milligram equivalents per enrollee by 7% and 13%, respectively. The reduction associated with MMLs was predominately in people aged 55-64, whereas the reduction associated with RMLs was largely in people aged 35-44 and aged 45-54. Our findings suggest that both MMLs and RMLs have the potential to reduce opioid prescribing in the privately insured population, especially for the middle-aged population.