Full length articleTrends in and correlates of medical marijuana use among adults in the United States
Introduction
Laws and policies related to marijuana use are shifting markedly in the U.S. By 2017, 29 states and the District of Columbia (DC) legalized medical marijuana use and several states and DC had legalized marijuana for nonmedical use (Hasin et al., 2015a, Hasin et al., 2017; Pacula and Sevigny, 2014; ProCon.org, 2017; Roy-Byrne et al., 2015). Most of the existing research has focused primarily on the impact of marijuana legalization on marijuana use prevalence among adults and youth in states that passed these laws compared to other states (Hasin et al., 2015a, Hasin et al., 2015b, Hasin et al., 2017; Martins et al., 2016; Pacula and Sevigny, 2014; Pacula et al., 2015; Silins et al., 2014; Wen et al., 2015; Wong and Clarke, 2015). Little is known about trends in medical marijuana use that is recommended by a doctor or other health care professional, especially trends in marijuana used exclusively for medical purposes (hereafter referred to as “medical-only”) among U.S. adults.
Marijuana use may help improve symptoms related to some medical conditions and psychiatric disorders (D’Souza and Ranganathan, 2015; Hill, 2015; Whiting et al., 2015).; however, heavy marijuana use is associated with adverse health consequences (e.g., cancer, chronic obstructive pulmonary disease, and heart disease), unemployment, lower income, diminished life satisfaction, and criminal behavior (Schauer et al., 2016; Volkow et al., 2014).
Using state registration data to track trends in registered medical marijuana participation, an earlier study found significant variations by state and within states over time (Fairman, 2016). A recent study found that 17% of marijuana users residing in medical marijuana states reported use for medical purposes (Lin et al., 2016). Recognizing that a physician might recommend medical marijuana use to a patient regardless of their residing state (Chaudhry et al., 2016; ProCon.org, 2017), another recent study reported that 21.2% of medical marijuana users resided in states that had not legalized such use (Compton et al., 2017).
As medical marijuana laws and practices evolve (Fairman, 2016; Pacula and Sevigny, 2014; Pacula et al., 2015), it is likely that there will be changes in the prevalence and correlates of medical marijuana use recommended by a doctor or other health care professional among adults in the U.S., in states with legalization of medical marijuana use (hereafter referred to as “medical marijuana states”), and in states without legalization of medical marijuana use (hereafter referred to as “nonmedical marijuana states”). Examining these trends and correlates over 3 years is the main purpose of this study. In addition, because individuals are not always aware of their state’s laws, we assessed whether and how self-reported marijuana use recommended by a doctor or other health care professional varied by the actual and the perceived medical marijuana legalization in their residing state. Our results may help inform ongoing marijuana policy discussions, help clinicians provide optimal care for patients using marijuana, and inform future research, public health messages, and programmatic efforts. We addressed the following questions:
- 1.
What are the prevalence of any medical marijuana use and of medical-only marijuana use among adults in each U.S. state? Have there been changes in the prevalence of any medical marijuana use and of medical-only marijuana use among all adults and among adult marijuana users in the U.S.?
- 2.
What are the correlates of any medical marijuana use and medical-only marijuana use among U.S. adults? Is perceived medical marijuana legalization in the residing state associated with any medical marijuana use and medical-only marijuana use? Do the correlates of any medical marijuana use and medical-only marijuana use differ by legalization status of medical marijuana use in the residing state?
- 3.
What are the prevalence and correlates of cannabis use disorders and of marijuana use frequency in the past 12 months among adults who used marijuana only for medical purposes (“medical-only marijuana users”) in the U.S.? Do they differ by legalization status of medical marijuana use in their residing state?
Section snippets
Study population
We examined data from adults aged 18 or older who participated in the 2013-2015 National Surveys on Drug Use and Health (NSDUH), a face-to-face yearly survey conducted by the Substance Abuse and Mental Health Services Administration (SAMHSA). NSDUH provides national and state representative data on marijuana and other substance use and use disorders among the U.S. civilian, noninstitutionalized population aged 12 or older (SAMHSA, 2017).
NSDUH employed a state-based design with an independent,
Prevalence of any medical and of medical-only marijuana use among adults by state
Based on the 147,200 sampled persons aged 18 or older from the 2013-2015 NSDUH, we estimated the annual average prevalence of any medical and of medical-only marijuana use among adults in the U.S. by state (Fig. 1). Despite state-by-state variations, the prevalence of each was generally much higher in medical marijuana states than nonmedical marijuana states.
Trend in and correlates of any medical marijuana use among adults
The 12-month prevalence of any medical marijuana use among adults in the U.S. increased by 34.2%, from 1.17% in 2013 to 1.57% in 2015 (p
Discussion
We found significant increases in any medical marijuana use as well as medical-only marijuana use among adults generally and among adult marijuana users during 2013-2015. For example, between 2013 and 2015, medical-only marijuana use increased by 41% among U.S. adults and increased by 30% among U.S. adult marijuana users (though it should be noted that the prevalence of each was generally low, and modest absolute differences produced these large relative changes). Moreover, the prevalence of
Conclusions
The 12-month prevalence of any medical and of medical-only marijuana use varied significantly by state and were generally much higher in medical marijuana states than nonmedical marijuana states. Adults were more likely to use marijuana medically in 2015 than in 2013 in both medical and nonmedical marijuana states, and adults were more likely to use marijuana medically-only in 2015 than in 2013 in the U.S. and in medical marijuana states. Among adults who used marijuana exclusively for medical
Contributors
Drs. Han and Compton designed the study. Dr. Han completed statistical analyses and originated and drafted the manuscript. All authors contributed to and have approved the final manuscript.
Role of Funding Source
Nothing declared.
Conflict of Interest
Unrelated to the submitted work, Compton reports ownership of stock in General Electric Co., 3 M Co., and Pfizer Inc., and Blanco reports ownership of stock in General Electric Co., Sanofi, and Eli Lilly Inc. Han and Jones have no conflicts to disclose.
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