Trends in Medical Marijuana Participation Across 13 US States and District of Columbia within the Context of the Changing Policy Environment

Introduction: Laws and policies towards medical marijuana (MMJ) in the US vary greatly between states and within states over time. Public health consequences regarding the impact of these laws is a concern, and the popularity of MMJ programs could directly or indirectly influence perceptions of harm, use, and other marijuana-related health outcomes. Therefore, trends in MMJ participation and differences by sex and age over time are compared for the first time across 13 US states and District of Columbia (DC) with mandatory registration requirements.

Methods:This study used publically-available state MMJ registry data collected by governmental agencies to calculate the rate of MMJ participation per 1,000 residents from 2001-2015. A subset of states provided data by sex and age. States with no or only voluntary MMJ patient registration requirements were not included (i.e., California, Washington, and Maine).

Results:From 2001-2008, MMJ registration was relatively low and flat (i.e., fewer than 5 per 1,000). Following federal policy changes in 2009 towards growers, dispensaries, and users, MMJ participation increased substantially in states that did not prohibit dispensaries, like Colorado, Montana, and Michigan (i.e., range of 15-30 per 1,000 adults), compared to states that prohibited them. State policy changes that restricted dispensaries and access for patients seeking MMJ for chronic pain preceded notable declines in participation in these three states. All other states have seen relatively slower, steady increases in participation. Two-thirds of MMJ registrants were male, but sex differences have decreased over time. Minor MMJ participation (<18 years) was small (<1%), but comparatively higher and increasing in Colorado and Oregon. Majority of MMJ patients were in 40s and 50s, but Colorado and Arizona had disproportionately more young adult (21-30) patients. Legalization of marijuana in Colorado does not appear to have greatly affected MMJ participation. As of 2015, at least 7.6 per 1,000 adults in states covered are registered to use marijuana medically.

Conclusions: MMJ participation is heterogeneous across and within states over time, and trends are likely affected by an interaction of state policies and federal response. Availability of dispensaries appears to coincide with larger increases in participation. Males seem to be early adopters into MMJ programs, and policies may differentially affect access for young adults. Marijuana legalization may have little affect on MMJ programs given economic incentives for remaining in them.