Full length articleAmong whom is cigarette smoking declining in the United States? The impact of cannabis use status, 2002–2015
Introduction
Cigarette smoking remains the leading preventable cause of death and disease worldwide (GBD 2015 Tobacco Collaborators, 2017GBD, 2015GBD 2015 Tobacco Collaborators, 2017). Within the United States (U.S.), smoking is responsible for 480,000 deaths annually; this amounts to more deaths each year than from human immunodeficiency virus (HIV), alcohol and illegal substance use, motor vehicle injuries, and firearm-related incidents, combined (Centers for Disease Control and Prevention, 2016a). The prevalence of smoking has declined tremendously in the U.S. since the mid-1960s, though it is currently estimated at approximately 15% in the US population (Centers for Disease Control and Prevention, 2016a). While the prevalence of smoking has declined among the general population, this decline has not been as dramatic among certain vulnerable groups (e.g., individuals who use alcohol and illicit substances).
Cigarette smoking is common among adults who use cannabis; estimates of cigarette smoking among current cannabis users range from 41 to 94% (Peters et al., 2012). Moreover, based on epidemiological data, the prevalence of cannabis use has been increasing over the past decade; estimates indicate that, between 2002 and 2014, the prevalence of cannabis use has increased significantly from 10.4% 13.3% (Compton et al., 2016). This pattern of co-use is troubling. A systematic review indicates that co-users of cannabis and tobacco are more likely to report cannabis use disorders and higher levels of psychosocial problems; as a result, comorbid users have greater difficulty quitting cannabis than do cannabis-only users (Peters et al., 2012). Further, co-users of cannabis and tobacco are at increased risk of toxicant exposure (Meier and Hatsukami, 2016)—including carbon monoxide, a contributor to cardiovascular and pulmonary disease (https://doi.org/10.1016/S0735-1097(01)01616-3)—and are at risk for numerous physical health morbidities, including respiratory distress (Moore et al., 2005; Taylor et al., 2000). Despite the observed decreases in the prevalence of cigarette smoking and increases in the prevalence of cannabis in recent years, it remains unknown whether and to what degree the prevalence of cigarette smoking has changed differentially among those who do and do not use cannabis over the same time period.
A number of studies have provided information on trends in tobacco use among cannabis users over time (Schauer et al., 2016, Schauer et al., 2017). Yet, unanswered questions remain. First, prior studies have examined multiple types of tobacco use combined—including cigarettes, cigars, pipe tobacco, blunts, and smokeless tobacco (Schauer et al., 2017), without separating out cigarette use from other tobacco use. Therefore, the trends in cigarette use vs. non-cigarette tobacco use has not been clear. This is especially relevant if the goal is to specifically understand trends in cigarette use given substantial co-use of cigarette use and alternative tobacco product use (e.g., blunt use; Fairman, 2015). Second, prior studies have examined any past month (Schauer et al., 2015, Schauer et al., 2016, Schauer et al., 2017) cigarette use among cannabis users, though the degree to which trends may differ by frequency of cigarette and/or cannabis use (i.e., daily versus non-daily) has not been examined. Taking into account the frequency of cigarette smoking, for instance, is particularly informative given that non-daily cigarette smokers appear to be quite distinct from daily smokers in several respects. Prior studies have suggested that—despite consistent evidence indicating the significant harms of non-daily cigarette use (Schane et al., 2010; U.S. Department of Health and Human Services, 2014)—non-daily cigarette smokers may not necessarily identify as “smokers” (Berg et al., 2009; Pulvers et al., 2014; Ridner et al., 2010), potentially reducing the likelihood that cessation messages will be perceived as salient, and therefore reducing effectiveness (Pulvers et al., 2014). Third, prior studies have not examined the potential impact of sociodemographic characteristics as potential moderators of these trends (Centers for Disease Control and Prevention, 2016a; Copeland and Swift, 2009; Guxens et al., 2007; Pacek et al., 2015). As a result, understanding the degree to which trends in cigarette smoking among individuals with various cannabis use status vary by demographic characteristics is critical to revealing whether various groups are differentially affected and may benefit from increased outreach and intervention.
In response to the above outlined gaps in the literature, the current study had three aims. The first was to investigate the relationship between current (past 30-day) cigarette smoking and current (past 30-day) cannabis use, stratified by demographic characteristics in 2015. The second aim was to estimate changes in the prevalence of past 30-day cigarette smoking among daily, non-daily, and non-users of cannabis from 2002 to 2015. The third aim was to estimate the prevalence of daily and non-daily cigarette smoking among daily and non-daily cannabis users, compared with non-users.
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Methods
Data were obtained from the 2002 to 2015 National Survey on Drug Use and Health (NSDUH) public use data files, for a combined total sample size of 782,156 individuals. The NSDUH is sponsored by the Substance Abuse and Mental Health Services Administration (SAMHSA) and is designed to provide estimates of the prevalence of extra-medical use of legal and illegal drugs in the household population of the U.S., age 12 and older. The survey employs a 50-state design with an independent multistage area
Past 30-day cigarette smoking and daily, non-daily, and non-cannabis use, by demographics, 2015
Past 30-day cigarette smoking was common among over half of daily cannabis users (54.57%; OR = 5.77, 95% CI = 4.83, 6.90) and among 40.17% of non-daily cannabis users (OR = 3.66, 95% CI = 3.30, 4.05) relative to 15.06% of non-cannabis users (Table 1). The strength of these relationships differed significantly by age, income, and race/ethnicity. The associations between daily cannabis use and cigarette smoking were stronger among individuals aged 12–17 (aOR = 41.80, 95% CI = 23.88, 73.18)
Discussion
To our knowledge, the present study is the first to examine trends in daily and non-daily cigarette smoking over time, stratified by frequency (daily, non-daily, no use) of current (past 30-day) cannabis use, in a nationally representative U.S. sample over the past decade. The study had several key findings. First, the prevalence of non-daily cigarette smoking has been increasing significantly among daily cannabis users over time (from 14.34% in 2002–17.86% in 2015). This is in contrast to the
Role of the funding source
Research reported in this publication was supported by the National Institute on Drug Abuse grants R01DA20892, K01DA043413, K24DA036955, and R01DA044171.
Conflict of interest
The authors have no conflicts of interest to declare.
Contributors
Authors Goodwin and Pacek conceptualized the research question. Author Pacek conducted the analyses, and wrote the first draft of the manuscript. Authors Copeland, Dierker, Cunningham, Martins, and Goodwin have critically reviewed, revised, and approved of the final manuscript.
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