Survey Examines Marijuana Use Among U.S. Adults

Prevalence Varies by Age, Presence of Medical Condition

October 16, 2019 01:52 pm Michael Devitt

As more states legalize or decriminalize marijuana(www.ncsl.org) for medical and/or recreational use, chances are good that family physicians will encounter more patients who use marijuana. Until recently, however, there hasn't been much hard data FPs could rely on to estimate how many of their patients might be using marijuana either with or without a prescription.

[marijuana joints and loose marijuana]

Results of a national survey(jamanetwork.com) published online Sept. 20 in JAMA Network Open have helped fill that knowledge gap. The survey found that adults who have documented medical conditions are far more likely to use marijuana than those who do not. It also found that more than one in nine young adults with a documented medical condition reported using marijuana on a daily basis.

"In general, there is a paucity of high-quality studies on the potential uses, benefits or negative health effects of marijuana," said Beth Anne Fox, M.D., M.P.H., of Kingsport, Tenn., a member of the AAFP's Commission of the Health of the Public and Science who led the development of the Academy's recently published position paper on marijuana and cannabinoids. "More rigorous research is needed as the use of marijuana and cannabinoids increases to better understand the short- and long-term effects of its use in order to better advise patients on its impact on their health."

Story Highlights
  • A survey of more than 169,000 American adults revealed that individuals with documented medical conditions are considerably more likely to use marijuana than those without a medical condition.
  • The survey also found that more than 25% of young adults with a medical condition currently use marijuana.
  • Family physicians are well-positioned to screen patients for marijuana use and to discuss the potential risks of marijuana use on personal health and well-being.

Survey Methods and Questions

For the study, researchers analyzed information from the Behavioral Risk Factor Surveillance System,(www.cdc.gov) an annual telephone survey that collects data from a representative sample of U.S. adults on health-related risk behaviors, chronic health conditions and use of preventive services. The study authors combined data from the 2016 and 2017 surveys, resulting in a sample of 169,036 adults.

In both surveys, participants were asked how many times they used marijuana in the past 30 days. Those who used marijuana on one or more days were categorized as current marijuana users; those who used it on 20 or more days were categorized as daily marijuana users.

Participants also were asked if they'd ever been told by a health care professional that they had any of the following medical conditions: stroke, heart attack, angina or coronary heart disease, asthma, COPD, diabetes, arthritis, kidney disease, depressive disorder, skin cancer, and other types of cancer.

In the 2017 BRFSS, participants were asked about the reasons for their marijuana use. Specifically, the survey asked if participants used marijuana to treat or decrease the symptoms of a health condition or for pleasure or satisfaction. Based on the responses, participants were classified as using marijuana for medical reasons, nonmedical reasons or both.

Marijuana Use by the Numbers

In all age groups except those 65 and older, adults who reported medical conditions had a higher prevalence of current and daily marijuana use than those without medical conditions. Overall, nearly 9% of people with medical conditions reported current marijuana use, and just under 4% reported daily marijuana use.

In adults with medical conditions, both current and daily marijuana use were highest in those ages 18-24. More than 25% of individuals in this age group were categorized as current marijuana users, and more than 11% were categorized as daily users. Prevalence decreased with age, with less than 1% of those 65 and older with medical conditions using marijuana on a daily basis.

Current marijuana use also varied by patient age and type of medical condition. In adults 18-34 with at least one medical condition, prevalence of marijuana use was highest in those with COPD; in adults 35-54, prevalence was highest in those with kidney disease; and in adults 55 and older, prevalence was highest in those with depression.

As for respondents' reasons for using the drug, 35.1% of current marijuana users overall reported using marijuana for medical reasons, 45.6% said they used it for nonmedical reasons, and 19.3% said they used it for both reasons.

These numbers varied slightly compared with current marijuana users with medical conditions. Adults in this group were more than twice as likely -- 45.5% vs. 21.8% -- as those without medical conditions to report using marijuana for medical reasons. However, a majority of people with at least one condition appeared to use marijuana recreationally: 36.2% reported using it for nonmedical purposes, and 18.3% used marijuana for both medical and nonmedical reasons.

Author Comments

The study authors concluded that because marijuana use is being seen in an increasingly positive light, and because the incidence of medical conditions increases with age, marijuana use could increase substantially among older adults going forward. Therefore, they said, "continuous surveillance of marijuana use across all age groups is warranted."

The authors recommended that clinicians not only screen patients for marijuana use, but also take the initiative in discussing risks and benefits of marijuana use, especially with regard to existing medical conditions. The authors also called for policymakers to closely monitor health-related claims and perceived benefits associated with marijuana use to ensure that patients fully understand the drug's effects on their health.

FP Expert Perspective

Fox cautioned against FPs reading too much into the findings because the survey data were collected only from select states and territories, and states were allowed to select which questions to include. Nevertheless, she said, the results "may be surprising to some physicians," especially regarding the use of marijuana by those with medical conditions.

"Family physicians may be interested in reviewing the information to generally have an estimate of the number of patients seen that may be using marijuana and for what purposes, as well as assessing potential impact of use on chronic medical conditions," Fox told AAFP News.

"I have patients who share this information as part of overall preventive health encounters, as well as during collection of past medical, social and family history for acute and chronic disease management within a trusting, collaborative patient-physician relationship," she said. "In my experience and practice, it is the most common substance of misuse."

Because FPs see people from virtually every demographic group, Fox thinks they are ideally positioned to counsel patients on marijuana use.

"Family physicians are instrumental in the diagnosis, treatment and prevention of substance use, including the diseases impacted or caused by the use of marijuana and cannabinoid products," Fox said.

"Family physicians should discuss the inappropriate use of cannabis products; their safe storage to avoid exposure to children and adolescents; the developmental and negative impacts of marijuana and cannabinoid use by at-risk populations, such as women who may become or are pregnant, children and adolescents; and the consequences of impaired driving and marijuana intoxication," she added.

Related AAFP News Coverage
AAFP Releases Marijuana, Cannabinoids Position Paper
Research Into Safety, Health Effects Sorely Needed, Says FP Expert

(9/20/2019)

Surgeon General Issues Advisory on Risks of Marijuana Use
Youth, Pregnant Women Encouraged to Stop Using

(9/12/2019)

More From AAFP
Familydoctor.org: Medical Marijuana(familydoctor.org)

Additional Resource
World Health Organization: The Health and Social Effects of Nonmedical Cannabis Use(www.who.int)