Opioid Mortality Following Implementation of Medical Cannabis Programs in the United States.

INTRODUCTION: The United States is in the midst of an opioid overdose epidemic. Emerging evidence suggests that medical cannabis (MC) may reduce use of opioids for pain in some individuals, with potential impacts on opioid-related overdose. However, there may be other important differences between states that did, and did not, adopt MC. METHODS: This study evaluated differences following legal MC sales on US opioid-related overdose deaths, corrected for population, from 1999 to 2017 using an interrupted time series. Comparisons by MC status were also made for Medicaid expansion and the Centers for Disease Control death certificate reporting quality (0: