Elsevier

Drug and Alcohol Dependence

Volume 169, 1 December 2016, Pages 41-47
Drug and Alcohol Dependence

Full length article
Prevalence and correlates of “Vaping” as a route of cannabis administration in medical cannabis patients

https://doi.org/10.1016/j.drugalcdep.2016.10.008Get rights and content

Highlights

  • About 39% of adults seeking medical cannabis certification reported vaping cannabis.

  • The majority (87.3%) of those who reported vaping also reported smoking cannabis.

  • Returning medical cannabis patients were more likely to report cannabis vaping.

  • Younger age, higher education, and frequency of cannabis use were related to vaping.

Abstract

Purpose

To examine the prevalence and correlates of vaporization (i.e., “vaping”) as a route of cannabis administration in a sample of medical cannabis patients.

Procedures

Adults ages 21 and older (N = 1485 M age = 45.1) who were seeking medical cannabis certification (either for the first time or as a renewal) at medical cannabis clinics in southern Michigan completed a screening assessment. Participants completed measures of route of cannabis administration, cannabis use, alcohol and other substance use.

Findings

An estimated 39% (n = 511) of the sample reported past-month cannabis vaping, but vaping as the sole route of cannabis administration was rare. Specifically, only 30 participants (2.3% of the full sample and 5.9% of those who reported any vaping) indicated vaping as the sole route of cannabis administration. The majority (87.3%) of those who reported vaping also reported smoking (combustion) as a route of cannabis administration. Being younger than age 44, having more than a high school education, engaging in nonmedical stimulant use, being a returning medical cannabis patient, and greater frequency of cannabis use were associated with higher odds of vaping at the bivariate level and with all variables considered simultaneously.

Conclusions

Vaping appears to be relatively common among medical cannabis patients, but is seldom used as the sole route of cannabis administration. Results highlight the importance of monitoring trends in vaping and other substance use behaviors in this population and underscore the need for longitudinal research into the motives, correlates, and consequences of cannabis vaping in medical cannabis patients.

Introduction

Since the appearance of electronic nicotine delivery systems in 2007, the use of electronic cigarettes or e-cigarettes (ECs), also known as “vaping,” has emerged as a growing public health concern (Benowitz, 2014, Pisinger and Døssing, 2014, Walton et al., 2015). More recently, vaporization as a route of cannabis administration has raised public health concerns similar to those for ECs. Specifically, vaping cannabis may be perceived as safer than smoking cannabis, which, in turn, might lead to greater initiation and/or use of cannabis (Budney et al., 2015, Cox, 2015, Fischer et al., 2015, Tashkin, 2015). Other potential concerns about cannabis vaping include the greater use of high-potency cannabis products, leading to increased risk of symptoms of cannabis use disorder, as well as the greater use of tobacco and cannabis together (Budney et al., 2015). By contrast, it was suggested that cannabis vaping could reduce the co-use of tobacco and cannabis (Gartner, 2015). The public health importance of understanding the potential risks and benefits of cannabis vaping takes on added significance in light of recent evidence that the prevalence of nonmedical cannabis use and cannabis use disorders increased sharply in the United States (US) in the 10-year period between 2001 and 2002 and 2012–2013 (Hasin et al., 2015).

Public health concerns about cannabis vaping are particularly relevant given the ongoing changes in cannabis legislation for medicinal purposes. As of July, 2016, twenty-five US states and the District of Columbia have passed legislation legalizing cannabis for medicinal purposes (National Conference of State Legislatures, 2016). In the state of Michigan, where the current research was conducted, the Michigan Medical Marihuana Act passed in 2008 legalized the use of cannabis for the treatment of debilitating medical conditions (e.g., cancer, glaucoma, severe or chronic pain). Qualifying patients or primary caregivers are required to obtain a registry identification card through a state registry program. As of January, 2016, 182,091 patients and 34,269 caregivers have been approved for medical cannabis registry identification cards in Michigan (Gaedeke, 2016).

Although a large body of evidence indicated that non-medical cannabis use was associated with a number of adverse health effects (Hall and Degenhardt, 2009, Volkow et al., 2014), results from recent narrative and meta-analytic reviews suggest that medical cannabis use may be associated with reductions in pain, nausea due to chemotherapy, and spasticity (Aggarwal, 2013, Borgelt et al., 2013, Hill, 2015, Koppel et al., 2014, Whiting et al., 2015). However, results from these reviews also showed that medical cannabis use was associated with increased odds of several adverse events, including risk of motor vehicle accidents, nausea and fatigue, gastrointestinal disorders, and psychiatric symptoms. More broadly, very little evidence exists to guide the method of administration, dosing, potential “strain” of cannabis or other domains related to dose/scheduling that are typical of FDA-approved medications.

The possibility that cannabis effects may vary by route of administration (Borgelt et al., 2013) highlights the importance of examining the prevalence and correlates of cannabis vaping in medical cannabis patients. Some potential benefits to vaping cannabis compared to smoking have been noted. For example, results from two randomized controlled trials showed that vaping cannabis compared to placebo was associated with reductions in neuropathic pain (Wallace et al., 2015, Wilsey et al., 2013). Other studies found that cannabis vaping was associated with lower likelihood of reporting respiratory problems (Earleywine and Barnwell, 2007) and improved respiratory function (Van Dam and Earleywine, 2010) compared to smoking. Some evidence also showed that cannabis vaping was associated with lower total cannabis use (Etter, 2015). Cannabis users might be particularly attracted to the potential of vaping as a means of reducing others’ exposure to secondhand cannabis smoke, and cannabis vaping might also reduce the simultaneous use of tobacco and cannabis (Gartner, 2015). However, evidence also indicated that vaping cannabis was associated with impaired cognitive performance (Wallace et al., 2015). It has also been argued that any beneficial effects of cannabis vaping on respiratory function are likely to be small and do not offset potential risks of vaping (Tashkin, 2015). In addition, vaping is often presented as an alternative to smoking cannabis, but little is known about the extent to which vaping occurs independently from, or in addition to, cannabis smoking.

Existing data have only provided a partial view of the potential prevalence of cannabis vaping. An early study based on a large sample of past-month cannabis users found that the prevalence of cannabis vaping was relatively low at 2.2% (Earleywine and Barnwell, 2007). A more recent study of 3847 students from five Connecticut high schools found that 5.4% of all students and 18.4% of all lifetime cannabis users reported ever using electronic cigarettes to vaporize cannabis (Morean et al., 2015), and the 2015 Monitoring the Future study found that, among adolescents who reported any lifetime use of electronic vaporizers, between 6 and 7% inhaled marijuana or hash oil when they last used an electronic cigarette (Johnston et al., 2016). A study based on a nationally representative consumer sample of U.S. adults showed that the prevalence of vaping among current (past one-month) cannabis users was 7.6% (Schauer et al., 2016), and results from a large study of past 12-month cannabis users in the 2014 Global Drug Survey indicated that 11.2% of US participants reported vaping as their most common current route of cannabis administration (Hindocha et al., 2016). By contrast, results based on a sample of lifetime cannabis users indicated that the past 1-month prevalence of any cannabis vaping was 37% (Lee et al., 2016), with lifetime vaping rates exceeding 50% (Borodovsky et al., 2016). Evidence also showed that vaping rates were higher among lifetime cannabis users residing in states with medical marijuana laws, and vaping rates increased as a function of states’ duration of medical cannabis legislation and the number of cannabis dispensaries (Borodovsky et al., 2016).

To our knowledge, only one study has documented prevalence rates of cannabis vaping among medical cannabis users. Pacula et al. (2016) collected data from an internet panel survey of a probability sample of adults residing in four states that have legalized medical cannabis use (Colorado, Washington, Oregon and New Mexico). Among medical cannabis users, the prevalence of vaping cannabis was 18%, compared to 3% among recreational cannabis users. The prevalence of vaping was highest (36.3%) among medical cannabis users who reported using both medically and recreationally.

There are few data available on the correlates of cannabis vaping. A small study found that a substantial percentage (45%) of cannabis users reported that vaping helped them to stop or reduce cannabis use (Etter, 2015). Those who use cannabis may also perceive that vaping is safer than smoking (Etter, 2015, Lau et al., 2015) and that vaping may confer health benefits (Malouff et al., 2013). Although there are concerns that vaping will lead to more frequent use of tobacco and cannabis together, evidence showed that vapers were less likely to combine tobacco and cannabis when vaping (Malouff et al., 2013; also see Lee et al., 2016). In addition, some data indicated that cannabis users perceive that vaping enhances the effects of cannabis (Malouff et al.), although Abrams et al. (2007) found no difference between smoking and vaping cannabis in terms of plasma THC concentration, and vaping had lower carbon monoxide exposure.

Overall, vaping has become a common mode of administration for tobacco and appears to be increasing for cannabis. Recent changes in legislation related to medical use of cannabis have raised numerous questions about efficacy and safety (Hill, 2015). However, no prior research has studied the prevalence and correlates of cannabis vaping in a sample of medical cannabis patients. Accordingly, the current research focused on medical cannabis patients and examined the extent to which they engage in vaping, whether vaping occurs instead of or in addition to cannabis use by other routes of administration, and the variables that are associated with cannabis vaping. Given that this is among the first studies to examine correlates of cannabis vaping among medical cannabis patients, we limited the covariates to demographic and substance use variables.

Section snippets

Material and methods

The current research is based on cross-sectional data from a project examining patterns of cannabis use. Adults ages 21 and older who were seeking medical cannabis at medical cannabis clinics in Michigan completed a screening assessment during a medical cannabis clinical visit.

Participants completed the screening assessment during the recruitment period for this study, which began in February, 2014 and ended in June, 2015. Of the 2569 participants who presented to the study sites during this

Results

Descriptive statistics reported in Table 1 show that the sample was mostly white, about 57% male, with a mean age of 45 years, and relatively well-educated (∼65% reported “at least some college”). The majority (56%) of participants were either currently married or in a long-term relationship, almost half (46.9%) were currently employed, and most (62%) were returning patients. Results in Table 1 also show that participants reported relatively frequent use of cannabis in the past 6 months, with

Discussion

To our knowledge, this study is the first to examine prevalence and correlates of vaping as a route of cannabis administration in a sample of medical cannabis patients. Results suggest that among medical cannabis patients, vaping is highly prevalent in combination with other modes of cannabis administration (e.g., smoking), but it rarely serves as the sole route of administration. Vaping is also more common among returning medical cannabis patients and those who are younger and better educated.

Conflict of interest

No conflict declared.

Role of funding source

This research was supported by grant R01 DA033397 from the National Institute on Drug Abuse (NIDA), National Institutes of Health. NIDA had no role in the study design; in the collection, analysis or interpretation of data; in the writing of the report; or in the decision to submit the article for publication.

Contributors

Dr. Ilgen (study principal investigator) conceptualized and designed the study. Drs. Cranford, Bohnert, Perron, and Ilgen drafted the manuscript. Ms. Bourque was responsible for data collection and review of study methods. Dr. Cranford was responsible for data analysis, and all authors contributed to and have approved the final manuscript.

Acknowledgement

We gratefully acknowledge Kierstdea Furey for her assistance with data collection and management.

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