Vaping patterns, nicotine dependence and reasons for vaping among American Indian dual users of cigarettes and electronic cigarettes

The prevalence of smoking in the U.S. is decreasing [1] and the prevalence of electronic cigarette (EC) use increasing [2]. Many individuals use ECs, or vape, in effort to reduce or quit smoking [3‐5]. While complete substitution of ECs for cigarettes has been associated with smoking cessation [6, 7], concomitant or “dual” use of ECs and cigarettes has not [8], and dual use is now the most common form of EC use [9]. Further, dual use has not been shown to reduce exposure to the harmful products of combustible cigarettes, including carcinogens [10‐18]. The American Cancer Society, as a result, strongly discourages the dual use of EC and cigarettes [19]. Additionally, recent evidence suggests that frequent vaping itself carries increased risk of cardiovascular disease [20, 21], and newer generation EC devices can achieve nicotine levels comparable or exceeding those of conventional cigarettes [22], increasing the potential for adverse effects from nicotine.

The American Indian (AI) population in general has a very high smoking prevalence, particularly in the Plains states [23‐26]. AI people also have the highest prevalence of EC use of any single-race group in the U.S. [27, 28]. However, use of EC by AI who smoke has been reported only rarely [29, 30], and the patterns and preferences of EC use among AI dual users, never. We now describe patterns, EC dependence, and preferences by focusing on the dual user subset, defined as people who smoked cigarettes and used ECs on some days or every day of the past 30 days. This common definition [31] minimizes the inclusion of people who merely experimented with ECs once or twice, and allows focus on persons with more habitual EC use.

The “Vaping among Smokers: A Cherokee Nation Cohort Study” was designed to provide estimates of the prevalence and patterns of EC use among adult AI smokers and has been described in detail elsewhere [30]. Briefly, in 2016 we recruited 375 adult AI men and women, who smoke, at a large Cherokee Nation Health Services outpatient facility in northeastern Oklahoma to participate in the study. Eligibility for services includes proof of AI or Alaska Native (AN) descent, such as a Certificate of Degree of Indian Blood (CDIB), from a federally recognized AI or Alaska Native tribe or community. Eligibility to participate in the cohort included being age 18 years or older, smoking at least 100 cigarettes in one’s lifetime, smoking in the past 30 days, and answering “yes” to both “Are you American Indian?” and “Do you have a CDIB card?”

Participants completed a survey including patterns of smoking and EC use. The current cross-sectional descriptive analysis is limited to the subset of dual users as defined below.

Of the 375 enrolled participants, 44 (12%) were dual users, defined as using ECs on some or all of the past 30 days.

Table 1 shows that among dual users, about one-third vaped 10 or more times a day, and less than one-half vaped fewer than 5 times per day. “Cigalikes” were the least frequently used product and tank systems were the most frequently used product. While 80% indicated that their e-liquid contained nicotine, 11% used e-liquid without nicotine, and 9% were unsure or did not know if their e-liquid contained nicotine. The most frequently reported nicotine content was 12 mg or less, but 14% did not know the nicotine concentration. More than half did not find vaping more enjoyable than smoking and most reported smoking before vaping on days they did both.

Vaping and smoking dependence item measures and scales are shown in Table 2. Although 76% reported smoking before vaping as noted above, vaping or smoking within the first 5 min of waking was not infrequent for either habit (31% and 24%, respectively), and cumulatively, the frequency of vaping or smoking within 30 min of waking was the same (55%). Individual measures show more dependence on smoking than vaping. Heaviness of vaping index and heaviness of smoking index did not differ significantly among the dual users (p = 0.22), but the mean PSDI dependence score for vaping was significantly lower than that for smoking (6.4 +/− 4.8 vs 11.0 +/− 5.0, respectively; p < .0001). Results were unchanged when median values of the PSDI were compared via the Wilcoxon signed-rank test (6 vs 11, p < .0001).

Reasons for vaping are shown in Fig. 1. The top three most commonly endorsed reasons for vaping were to cut down on smoking, liking EC flavors, and being able to vape in places wherein smoking is not allowed. Perceiving less harm to others or to oneself compared with smoking were the next most frequent responses. Less than one-half endorsed using EC to reduce stress, reduce cost, or because other persons important to them used EC. Other reasons (write in) for EC use were endorsed by only two (4.5%) participants.

In this cohort of adult AI persons who smoke, the prevalence of dual use, defined as using EC on some or all of the past 30 days, was 12%. This definition of dual use is similar to other longitudinal studies [7, 36] and helps to exclude recent experimenters or infrequent users [31]. Other studies vary widely in estimates of prevalence of dual use by smokers. In a 2014 study, nearly 52% of a cohort of smokers used ECs either daily or more than just a few days [7]. However, in a 2013 study, prevalence of EC use more than 50 times during lifetime was only 3.8% among smokers [37] and among current smokers in the Current Population Survey in 2014, regular EC use among smokers was 3.6% [38]. Definitions of dual use may vary enough to limit our ability to directly compare prevalence estimates between different cohorts, and the rapid rise in EC use also limits comparison with older studies. Standardized definitions of dual use will be useful in future studies.