Abstract
Background:
The objective was to examine the reasons smokers have discontinued or chosen not to use electronic nicotine delivery systems (ENDS).
Methods:
Data were obtained from a national probability sample of 1843 US adult current smokers who were not current ENDS users pooled from the 2017 and 2018 annual, cross-sectional Tobacco Products and Risk Perceptions Surveys. Participants reported their ENDS use, reasons for discontinuing or not initiating ENDS use, quit smoking intentions, perceptions, and use intentions. Weighted proportions and logistic regression models were estimated.
Results:
Twenty-three percent of smokers were former ENDS users who reported prior “regular use”, and 7.5% were former ENDS users who reported regular use. Three most cited reasons for discontinuing ENDS were: ENDS “didn’t feel like smoking” (23%), “only ever tried them to see what they were like” (20%), and “didn’t help me deal with cravings for smoking” (14%). Reasons for discontinuing ENDS were associated with the regularity of former ENDS use and ENDS type. Nearly 40% of current smokers had not tried ENDS with the most commonly cited reasons being not wanting to substitute one addiction for another (60%), concerns about their safety (53%), skepticism that ENDS could help them quit smoking (52%), and cost (43%). Reasons were associated with smoking quit intentions, harm perceptions, and age.
Conclusion:
Whereas smokers who had formerly used ENDS cited inadequate craving reduction or incomparability to smoking for their discontinuation, the larger segment of smokers who have never used ENDS cited “safety,” “effectiveness,” and “costs” as reasons for non-use.
Keywords: Electronic cigarettes, smoking/harm reduction, smokers, survey research
1. INTRODUCTION
The weight of current scientific evidence about electronic nicotine delivery systems (ENDS) suggests that these products can be a substantially less harmful, though not harmless, alternative source of nicotine for cigarette smokers with potential for population harm reduction under the right conditions (McNeill et al., 2018; National Academies of Sciences, Engineering, and Medicine, 2018; Royal College of Physicians, 2016). For ENDS to achieve population health improvement, smokers who would not have otherwise quit smoking would need to completely substitute their smoking with ENDS, optimally in transition to complete tobacco and nicotine abstinence, at levels that counter any concomitant increases in youth and young adult nicotine and tobacco use caused by ENDS (Levy et al., 2017; Warner and Mendez, 2018). Most smokers who use ENDS report using them to quit or reduce smoking, and a recent randomized trial found that a second-generation ENDS was more efficacious than nicotine replacement therapy under advantageous circumstances where trial participants were provided a newer generation ENDS, cessation counseling, and instruction and guidance on using the provided ENDS (Hajek et al., 2019; Simonavicius et al., 2017; Yong et al., 2019). Studies of U.S. smokers’ use of ENDS under real-world conditions have generated inconsistent findings regarding their effectiveness for quitting smoking (Giovenco and Delnevo, 2018; Halpern et al., 2018; Levy et al., 2018; Rigotti et al., 2018; Sweet et al., 2019; Weaver et al., 2018; Zhu et al., 2017).
While much focus has been on the dual use of cigarettes and ENDS, the smokers who have tried or used but discontinued ENDS while continuing to smoke has been referred to as “a missed opportunity for harm reduction” (Simonavicius et al., 2017). Although fewer in number compared to dual users, approximately one-quarter of US adult smokers in 2015 had tried or used but discontinued ENDS while continuing to smoke (Weaver et al., 2017). In recent longitudinal research, more than one-third of dual users at baseline had discontinued using ENDS while continuing to smoke within one year and more than one-half had done so within two years (Kasza et al., 2018; Manzoli et al., 2017; Weaver et al., 2018). In a 2016 survey of British smokers, the most common reasons given for discontinuing ENDS were that they did not sufficiently mimic the feel of smoking or reduce cravings to smoke (Simonavicius et al., 2017). Two US surveys conducted in 2013–2014 found that one-third of smokers who discontinued ENDS indicated they were too expensive or did not feel “like smoking cigarettes”, while substantial proportions also referred to their taste, concerns about health risks, and malfunction or poor function as reasons (Biener et al., 2015; Biener and Hargraves, 2015). A more recent, multi-country study that included U.S. participants reported the top reasons given by smokers for discontinuing ENDS centered around dissatisfaction with ENDS, particularly with relieving cravings to smoke or helping them quit smoking (Yong et al., 2019). Since these studies were conducted, the ENDS market and regulatory landscapes have continued to evolve (Huang et al., 2019a; Rigotti, 2018). These changes, as well as the intense public scrutiny of ENDS in the U.S., over the past couple years could have led to shifts in reasons for non-use.
Smokers who want to quit smoking but have not tried ENDS also warrant examination. Most smokers express regret having ever started smoking and want to quit, but nearly 40% of smokers have not tried ENDS despite their marketing and promotion as an alternative to smoking (Pechacek et al., 2017; Weaver et al., 2017). To the extent that ENDS can be effective for achieving complete smoking abstinence, factors that reduce their appeal to and inhibit their uptake by a substantial segment of adult smokers could limit their population harm reduction potential. One possible explanation is the growing perception among smokers that using ENDS is equally or more harmful than smoking cigarettes (Huang et al., 2019b; Majeed et al., 2017; Nyman et al., 2019). In the UK, which has observed lower prevalence but similar trends in this perception, the modal reason given by smokers for not trying ENDS in 2016 was concerns about their safety (27%), followed closely by not wanting to substitute one addiction for another (25%) and doubts about their effectiveness for quitting or cutting down their smoking (22%) (Action on Smoking and Health, 2016; Wilson et al., 2019).
Continued monitoring is needed of smokers’ reasons for the disuse of ENDS, which may be changing as a result of market evolution and the intense and highly public, polarized discussions around ENDS. Understanding the smoking and ENDS use characteristics, perceptions, and intentions to use ENDS in the future of smokers who have tried or used but discontinued ENDS or who have chosen not to use ENDS while continuing to smoke and their reasons for doing so could inform efforts to achieve their harm reduction potential. For instance, targeted education campaigns could inform smokers who cite concerns about the safety of ENDS as their reason for not trying or for discontinuing ENDS use and perceive them to be as harmful as or more harmful than smoking cigarettes about the current evidence on the relative harm of ENDS relative to cigarettes. And data about these smokers’ openness and intentions for future use of ENDS provide useful information about the extent to which their decision to not use ENDS could be malleable to external factors. Accordingly, the objectives of this study are to examine: (a) smoking and ENDS use characteristics, perceptions (such as perceived harm and, for former users, perceived enjoyment), and future use intentions among those smokers who have either not tried or discontinued using ENDS; (b) the reasons a segment of smokers give for discontinuing ENDS, overall and by extent of their prior ENDS use (experimental vs. regular), type of ENDS, and flavor; and (c) the reasons given by smokers for not trying ENDS, overall and by smoking quit intentions, age, and perceived harm of ENDS.
2. METHODS
2.1. Study Sample and Procedures
Data were from the 2017 (August-September) and 2018 (November-December) Tobacco Products and Risk Perceptions Surveys of national probability samples drawn from GfK’s online KnowledgePanel. Survey participants were adults (18+ years) and were selected with probabilities proportional to size after application of the panel demographic poststratification weight. The 2018 sample excluded anyone who completed the 2017 survey. Computers with internet access were provided for panelists who did not have them. All participants received a cash equivalent of $5 for their participation. A study-specific poststratification weight was computed using an iterative proportional fitting (raking) procedure to adjust for survey non-response as well as for oversampling of smokers. Demographic and geographic distributions from the most recent Current Population Survey were employed as benchmarks for adjustment, and included sex, age, race/ethnicity, education, household income, census region and metropolitan area.
In 2017, 8229 KnowledgePanel members were invited to participate in the survey, and 6033 qualified for and completed the survey. Twenty-two cases were excluded due to refusing to answer more than half the survey questions and 19 were removed due to low duration or being flagged for highly improbable or incompatible responses, yielding a final stage completion rate of 72.8%. In 2018, 7997 KnowledgePanel members were invited to participate in the survey, and 6018 qualified for and completed the survey. Twenty-nine cases were excluded due to refusing to answer more than half of the survey questions, to low survey duration (< 3 minutes), or being flagged twice for highly improbable or incompatible responses, yielding a sample of 5989 cases and a final stage completion rate of 75.8%. The analytic sample for the present study includes 1843 current smokers who were not current ENDS users pooled from the 2017 and 2018 surveys.
2.2. Measures
2.2.1. Cigarette Smoking and ENDS Use Status.
Participants who reported smoking at least 100 cigarettes in their lives were classified as current smokers if currently smoking cigarettes every day or some days. Current daily smokers were asked to report the typical number of cigarettes they smoked each day. To assess ENDS use, respondents were first provided a description and an image of ENDS depicting various device types. Lifetime (ever) use of ENDS was then assessed by asking, “Have you ever used electronic vapor products, even one or two times?” If they reported no, they were classified as never ENDS users. Those respondents reporting lifetime ENDS use were classified as former ENDS users if they selected not at all to “Do you now use electronic vapor products every day, some days, rarely, or not at all?” Former ENDS users were then sub classified as either never regular users if they selected no to, “Have you ever used electronic vapor products fairly regularly?” or as regular (former) ENDS users if they selected yes.
2.2.2. Reasons for Discontinuing/Not Initiating ENDS Use.
Current smokers who reported previous but not current use of ENDS were asked a question obtained from the 2016 ASH Smokefree GB survey (Action on Smoking and Health, 2016), “What is the main reason you stopped using electronic vapor products?” Respondents could select one reason among twelve provided reasons, including options for Other and Don’t know/can’t remember (see Table 2). Current smokers who reported never using ENDS were asked, “Which of the following are reasons you have not tried an electronic vapor product” and responded either yes or no for each of twelve reasons (see Table 3). They were also asked if there was some other reason and prompted to specify the reason. These responses were independently reviewed by two coders, and responses that by consensus matched an existing response option were re-coded to reflect the matched response.
Table 2.
The reasons US adult current smokers provide for discontinuing ENDS use, overall and by regularity of ENDS use and ENDS device type (2017–2018)
| Overall (n=816) | Former Experimental vs. Former Regular ENDS Users (punadj < .001, padj = .003) | ENDS Device Type (punadj = .012, padj < .001) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Former experimental ENDS users (n=611) | Former regular ENDS users (n=205) | Rechargeable, refillable users (n=299) | Rechargeable, non-refillable users (n=180) | Non-rechargeable users (n=158) | |||||||||||||
| Reason for Discontinuing ENDS | n | Weighted % (95% CI) | n | Weighted % (95% CI) | n | Weighted % (95% CI) | n | Weighted % (95% CI) | n | Weighted % (95% CI) | n | Weighted % (95% CI) | |||||
| They didn’t feel like smoking a cigarette | 183 | 22.9 (19.3, 26.9) | 139 | 23.0 (18.9, 27.6) | 44 | 22.5 (15.7, 31.1) | 68 | 24.0 (18.1, 31.1) | 60 | 34.2 (25.7, 43.9) | 31 | 18.8 (12.4, 27.5) | |||||
| I only ever tried them to see what they were like | 177 | 20.3 (17.0, 24.0) | 165 | 25.2 (21.1, 29.8) | 12 | 5.8 (3.0, 11.0) | 42 | 12.8 (8.9, 18.2) | 27 | 15.7 (9.7, 24.4) | 42 | 25.2 (17.6, 34.6) | |||||
| They didn’t help me deal with cravings for smoking | 131 | 14.4 (11.7, 17.6) | 89 | 13.2 (10.2, 16.9) | 42 | 17.9 (12.5, 25.1) | 59 | 19.6 (14.6, 25.8) | 33 | 14.2 (9.3, 21.1) | 28 | 15.4 (9.6, 23.8) | |||||
| I was concerned they were not safe enough | 77 | 10.2 (7.7, 13.3) | 54 | 9.7 (6.9, 13.4) | 23 | 11.7 (7.0, 18.8) | 38 | 12.1 (8.3, 17.4) | 16 | 10.6 (5.6, 19.4) | 12 | 8.3 (4.2, 15.8) | |||||
| Don’t know/can’t remember | 68 | 9.3 (6.8, 12.6) | 52 | 9.7 (6.9, 13.6) | 16 | 8.2 (4.0, 15.8) | 17 | 4.9 (2.8, 8.3) | 9 | 8.9 (3.9, 19.2) | 16 | 12.5 (6.3, 23.3) | |||||
| They cost too much | 43 | 5.2 (3.6, 7.4) | 31 | 5.4 (3.5, 8.2) | 12 | 4.4 (2.3, 8.3) | 12 | 3.2 (1.7, 5.9) | 9 | 4.6 (2.3, 9.1) | 10 | 8.9 (4.0, 18.6) | |||||
| Other (specify) | 39 | 4.2 (2.8, 6.2) | 31 | 4.5 (2.8, 7.0) | 8 | 3.3 (1.6, 6.8) | 9 | 2.8 (1.3, 5.6) | 9 | 4.3 (1.7, 10.2) | 7 | 2.2 (0.9, 5.3) | |||||
| I felt I was using them too often compared with smoking |
27 | 4.6 (3.0, 7.0) | 11 | 3.0 (1.5, 5.7) | 16 | 9.4 (5.4, 15.7) | 16 | 6.9 (3.9, 11.7) | 2 | 1.1 (0.3, 4.5) | 6 | 5.3 (2.2, 12.2) | |||||
| Refills and replacements were not easily available | 20 | 2.9 (1.6, 5.3) | 8 | 2.0 (0.8, 4.9) | 12 | 5.6 (2.6, 11.8) | 7 | 3.2 (1.3, 7.6) | 7 | 2.6 (1.1, 5.9) | 1 | 0.4 (0.1, 2.8) | |||||
| They were difficult to use or refill | 16 | 1.3 (0.7, 2.4) | 9 | 0.9 (0.4, 1.9) | 7 | 2.6 (1.1, 6.3) | 8 | 2.3 (1.0, 5.1) | 4 | 1.3 (0.5, 3.7) | 1 | 0.2 (0.0, 1.6) | |||||
| They kept leaking | 14 | 1.6 (0.7, 3.4) | 9 | 1.5 (0.5, 4.1) | 5 | 1.8 (0.7, 4.5) | 13 | 3.5 (1.5, 7.8) | 0 | 0.0 (0.0, 0.0) | 1 | 1.2 (0.2, 8.2) | |||||
| A health professional told me to stop | 9 | 1.2 (0.4, 3.1) | 6 | 0.7 (0.3, 1.7) | 3 | 2.6 (0.5, 12.3) | 5 | 1.9 (0.5, 7.8) | 2 | 0.8 (0.2, 3.6) | 1 | 0.8 (0.1, 5.3) | |||||
| They felt too much like smoking a cigarette | 8 | 1.5 (0.7, 3.3) | 4 | 0.8 (0.2, 2.5) | 4 | 3.6 (1.2, 10.3) | 3 | 2.3 (0.7, 7.3) | 1 | 1.2 (0.2, 8.2) | 2 | 0.9 (0.2, 3.7) | |||||
| I was embarrassed to use them in public | 4 | 0.6 (0.2, 1.8) | 3 | 0.6 (0.1, 2.4) | 1 | 0.6 (0.1, 3.9) | 2 | 0.5 (0.1, 2.3) | 1 | 0.3 (0.0, 2.2) | 0 | 0.0 (0.0, 0.0) | |||||
ENDS = electronic nicotine delivery system; n = unweighted frequency; CI = confidence interval. Column percentages are reported. Weighted unadjusted and adjusted logistic regression models were estimated and a likelihood ratio test was performed to evaluate the association between the column variables (former experimental vs. former regular ENDS user; ENDS device type) with the row variable (reason for discontinuing ENDS). P-values are reported for unadjusted (punadj) and adjusted (padj) models. Adjusted models controlled for age, sex, and the other column variable.
Table 3.
The reasons US adult current smokers provide for never having tried or used ENDS, overall and stratified by smoking quit attentions and age (2017–2018)
| Overall | Smoking Quit Intentions | Age | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Less than 6 months | More than 6 months or no plan | 18–29 years | 30+ years | |||||||||||||
| n | Weighted % (95% CI) | n | Weighted % (95% CI) | n | Weighted % (95% CI) | punadj, padj | n | Weighted % (95% CI) | n | Weighted % (95% CI) | punadj, padj | |||||
| I do not want to substitute one addiction for another | 546 | 60.0 (55.7, 64.1) | 223 | 68.9 (61.5, 75.4) | 321 | 55.7 (50.3, 60.9) | (.003, < .001) | 33 | 52.2 (36.3, 67.7) | 513 | 61.0 (56.7, 65.2) | (.17, .29) | ||||
| I am concerned they are not safe enough | 490 | 52.7 (48.4, 56.9) | 198 | 61.5 (54.1, 68.3) | 289 | 48.3 (43.0, 53.7) | (.004, .001) | 28 | 42.7 (27.9, 58.9) | 462 | 54.1 (49.7, 58.4) | (.082, .056) | ||||
| I do not think they would help me to quit or cut down | 477 | 52.0 (47.8, 56.3) | 179 | 55.7 (48.4, 62.7) | 297 | 50.5 (45.1, 55.8) | (.25, .046) | 32 | 53.3 (37.3, 68.6) | 445 | 51.9 (47.5, 56.2) | (.83, .97) | ||||
| They cost too much | 362 | 42.8 (38.6, 47.1) | 134 | 43.9 (37.0, 51.0) | 227 | 42.4 (37.2, 47.8) | (.75, .13) | 29 | 50.9 (35.2, 66.5) | 333 | 41.7 (37.5, 46.0) | (.16, .59) | ||||
| I do not want to quit smoking | 293 | 35.1 (31.0, 39.3) | 49 | 17.1 (12.2, 23.4) | 243 | 44.0 (38.8, 49.4) | (< .001, < .001) | 17 | 39.9 (25.1, 56.8) | 276 | 34.4 (30.4, 38.6) | (.38, .77) | ||||
| There are too many products to choose from | 290 | 32.0 (28.3, 36.1) | 115 | 34.7 (28.5, 41.5) | 173 | 30.7 (26.0, 35.8) | (.35, .065) | 18 | 29.1 (16.8, 45.5) | 272 | 32.4 (28.6, 36.5) | (.58, .49) | ||||
| I haven’t gotten around to it yet |
240 | 27.2 (23.5, 31.1) | 89 | 30.1 (23.9, 37.1) | 149 | 25.6 (21.2, 30.6) | (.27, .035) | 19 | 39.7 (25.0, 56.5) | 221 | 25.4 (21.9, 29.2) | (.018, .031) | ||||
| I do not like the way they look | 232 | 24.5 (21.2, 28.2) | 90 | 24.9 (19.8, 30.9) | 141 | 24.4 (20.1, 29.2) | (.89, .15) | 14 | 23.3 (12.7, 38.8) | 218 | 24.7 (21.3, 28.5) | (.81, .76) | ||||
| I am not addicted to smoking and don’t need help to quit |
166 | 19.7 (16.5, 23.4) | 55 | 17.4 (12.9, 23.1) | 108 | 20.6 (16.5, 25.4) | (.38, .015) | 13 | 28.7 (15.7, 46.4) | 153 | 18.5 (15.5, 21.9) | (.061, .25) | ||||
| I am using other things to help me quit smoking | 163 | 15.7 (13.0, 18.8) | 103 | 28.8 (23.1, 35.3) | 59 | 9.2 (6.6, 12.6) | (< .001, < .001) | 9 | 11.6 (4.7, 25.8) | 154 | 16.3 (13.5, 19.5) | (.31, .43) | ||||
| I would be embarrassed to use them in public | 150 | 16.7 (13.8, 20.0) | 56 | 17.2 (12.8, 22.8) | 93 | 16.4 (12.8, 20.7) | (.81, .17) | 12 | 22.9 (11.8, 39.8) | 138 | 15.8 (13.1, 18.9) | (.16, .25) | ||||
| They are too difficult to get hold of | 78 | 9.2 (7.1, 11.8) | 33 | 10.2 (6.8, 14.9) | 44 | 8.6 (6.1, 12.1) | (.56, .13) | 4 | 9.3 (3.0, 25.0) | 74 | 9.2 (7.1, 11.8) | (.97, .67) | ||||
| Other | 53 | 6.0 (4.4, 8.3) | 18 | 7.2 (4.3, 11.9) | 35 | 5.5 (3.7, 8.2) | (.45, .43) | 2 | 5.0 (1.2, 18.6) | 51 | 6.2 (4.5, 8.5) | (.69, .91) | ||||
ENDS = electronic nicotine delivery system; n = unweighted frequency; CI = confidence interval. Column percentages are reported for each reason. Participants could select multiple reasons. Weighted unadjusted and adjusted logistic regression models were estimated and a likelihood ratio test was performed to evaluate the association between the column variables (smoking quit intentions; age) with each row variable (reason for never having tried or used ENDS). P-values are reported for unadjusted (punadj) and adjusted (padj) models. Adjusted models controlled for sex, race/ethnicity, household income, education, perceived relative harm of ENDS vs. cigarettes, and the other column variable. Statistically significant effects (p < .05) are denoted by boldface p-values.
2.2.3. Quit Smoking Intentions.
Current smokers indicated their intentions to quit smoking in response to “What best describes your plans regarding quitting smoking cigarettes?” with six response options ranging from intend to quit in the next 7 days to never plan to quit. Responses were dichotomized to reflect either intentions to quit within the next 6 months or after the next 6 months (or never).
2.2.4. ENDS Characteristics, Perceptions, and Use Intentions.
Former ENDS users reported whether the electronic vapor device they had used most of the time was rechargeable and whether it was refillable (has a tank or cartridge that is intended by the manufacturer to be refilled with e-liquid by the user).
Perceptions of the harmfulness of ENDS relative to cigarettes among those who reported awareness of ENDS was measured by the question, “Is using electronic vapor products less harmful, about the same, or more harmful than smoking regular cigarettes?” and a 5-point response scale ranging from much less harmful to much more harmful or I don’t know. For analyses, response options much less harmful and less harmful were collapsed, as were the options more harmful and much more harmful. The perceived harm of nicotine for adults was assessed by the question, “Most tobacco products, including most electronic vapor products, contain nicotine. When used by the following groups, how harmful is nicotine in amounts usually found in tobacco products?” and a 4-point response scale ranging from not harmful to definitely harmful or don’t know. The perceived enjoyability of ENDS compared to combustible cigarettes was assessed among smokers who reported ever use of ENDS with the question, “How would you compare the experience of using electronic vapor products to smoking regular cigarettes?” Participants responded to a three-point scale: electronic vapor products are more enjoyable, equally enjoyable, or electronic vapor products are less enjoyable.
Intentions to use ENDS in the future was assessed by two items: “Do you think you will try an electronic vapor product (again) soon?” and “If one of your best friends were to offer you an electronic vapor product, would you [try/use] it?” Responses were measured on a four-point response scale ranging from definitely not to definitely yes.
2.2.5. Respondent Characteristics.
Data on demographic and other respondent characteristics were obtained from profile surveys administered by GfK to KnowledgePanel panelists. These characteristics included sex, age, race/ethnicity, educational attainment, and annual household income.
2.3. Statistical Analysis
Among cigarette smokers, stratified by their prior ENDS use, we calculated proportions and their 95% confidence intervals for smoking and ENDS use characteristics. Binary and multinomial logistic regression models were used to conduct likelihood ratio tests to test differences in these proportions by ENDS use. Among smokers who had tried but discontinued ENDS, proportions were estimated for the reasons they selected for discontinuing ENDS and multinomial logistic regression models were estimated to perform likelihood ratio tests to test whether reasons were associated with whether ENDS had been used regularly and with device type. Among smokers who never tried ENDS, proportions were estimated for their endorsement of each of the reasons provided for never trying ENDS. For each reason, likelihood ratio tests via binary logistic regression were conducted to test whether endorsement of the reason was associated with smoking quit intentions, the perceived relative harm of ENDS, and age (as we expected that reasons pertaining to addiction may be less salient and reasons pertaining to cost or may be more salient for younger adults). Both unadjusted models and models that adjusted for sociodemographic and, depending on the analysis, other variables were estimated. For all analyses, a study-specific poststratification weight was used to adjust analyses for sources of sampling and non-sampling error. Proportions were estimated using the Survey package (v. 3.33–2) for the R statistical program (v. 3.5.0) (Lumley, 2017, 2004). A two-tailed α = .05 was set a priori for the likelihood ratio tests, which were.
3. RESULTS
3.1. Smoking Status and ENDS Use Characteristics, Perceptions, and Future Use Intentions
Among all current smokers, 39.9% (95% CI: 37.4, 42.4) were never ENDS users, 23.4% (95% CI: 21.3, 25.6) were former but never regular ENDS users, and 8.1% (95% CI: 6.8, 9.6) were former, regular ENDS users. Table 1 provides a summary of the smoking and ENDS use characteristics and perceptions of these smoker groups (sociodemographic characteristics are reported in supplementary Table S1). Statistically significant group differences were observed for all variables shown.
Table 1.
Smoking and ENDS use characteristics among US adult smokers by prior ENDS use (2017–2018)
| Former ENDS users (n=208) | Former experimental ENDS users (n=613) | Never ENDS users (n=1022) | |||||||
|---|---|---|---|---|---|---|---|---|---|
| n | Weighted % (95% CI) | n | Weighted % (95% CI) | n | Weighted % (95% CI) | ||||
| Smoking quit plans (punadj = .027, padj < .001) | |||||||||
| Within 6 months | 83 | 38.2 (30.2, 46.9) | 190 | 27.9 (23.7, 32.5) | 357 | 34.6 (30.9, 38.4) | |||
| > 6 months | 125 | 61.8 (53.1, 69.8) | 421 | 72.1 (67.5, 76.3) | 659 | 65.4 (61.6, 69.1) | |||
| Smoking frequency (punadj = .024, padj < .001) | |||||||||
| Non-daily | 49 | 25.6 (18.5, 34.3) | 144 | 24.9 (20.5, 29.8) | 289 | 29.9 (26.4, 33.7) | |||
| Daily (1–9 CPD) | 27 | 13.5 (8.8, 20.0) | 92 | 14.7 (11.5, 18.6) | 178 | 18.9 (16.0, 22.3) | |||
| Daily (10+ CPD) | 132 | 61.0 (52.1, 69.2) | 376 | 60.5 (55.3, 65.4) | 551 | 51.2 (47.2, 55.1) | |||
| ENDS device type (punadj < .001, padj < .001) | |||||||||
| Non-rechargeable | 20 | 9.0 (5.3, 15.0) | 138 | 29.8 (24.6, 35.5) | -- | -- | |||
| Rechargeable, non-refillable | 42 | 19.6 (13.3, 27.9) | 139 | 30.7 (25.4, 36.5) | -- | -- | |||
| Rechargeable, refillable | 128 | 71.4 (62.7, 78.8) | 173 | 39.6 (33.9, 45.6) | -- | -- | |||
| Perceived relative harm of ENDS (punadj < .001, padj < .001) | |||||||||
| Less harmful than cigarettes | 82 | 37.8 (29.7, 46.7) | 191 | 29.2 (24.8, 34.1) | 148 | 15.3 (12.6, 18.6) | |||
| About the same harm as cigarettes | 69 | 30.8 (23.6, 39.0) | 212 | 35.6 (30.8, 40.8) | 356 | 41.7 (37.5, 45.9) | |||
| More harmful than cigarettes | 15 | 9.7 (5.2, 17.4) | 47 | 7.0 (5.0, 9.9) | 75 | 9.8 (7.5, 12.6) | |||
| I don’t know | 40 | 21.7 (15.0, 30.3) | 158 | 28.1 (23.6, 33.1) | 287 | 33.2 (29.3, 37.4) | |||
| Perceived harm of nicotine for adults (punadj = .032, padj < .001) | |||||||||
| Definitely harmful | 118 | 55.6 (46.7, 64.2) | 347 | 56.5 (51.3, 61.6) | 587 | 56.1 (52.1, 60.0) | |||
| Maybe harmful | 60 | 25.7 (19.0, 33.7) | 175 | 28.3 (23.9, 33.2) | 243 | 23.8 (20.6, 27.3) | |||
| Unlikely harmful | 7 | 4.2 (1.4, 11.6) | 22 | 3.9 (2.2, 6.9) | 59 | 5.9 (4.3, 7.9) | |||
| Not harmful | 6 | 4.6 (1.5, 12.8) | 7 | 1.5 (0.7, 3.4) | 19 | 2.1 (1.2, 3.9) | |||
| Don’t know | 17 | 9.9 (5.6, 16.8) | 61 | 9.8 (7.0, 13.4) | 110 | 12.1 (9.6, 15.1) | |||
| Enjoyability of ENDS compared to cigarettes (punadj < .001, padj < .001) | |||||||||
| ENDS are less enjoyable | 155 | 71.7 (63.1, 79.1) | 521 | 82.8 (77.9, 86.7) | -- | -- | |||
| Equally enjoyable | 37 | 18.2 (12.6, 25.6) | 73 | 15.6 (11.8, 20.4) | -- | -- | |||
| ENDS are more enjoyable | 16 | 10.1 (5.4, 18.0) | 10 | 1.6 (0.8, 3.4) | -- | -- | |||
| Will try ENDS soon (punadj < .001, padj < .001) | |||||||||
| Definitely not | 52 | 18.6 (13.5, 25.1) | 261 | 43.5 (38.5, 48.7) | 467 | 52.8 (48.5, 57.1) | |||
| Probably not | 91 | 48.4 (39.7, 57.2) | 262 | 42.5 (37.4, 47.7) | 289 | 33.8 (29.8, 38.0) | |||
| Probably yes | 57 | 29.0 (21.4, 37.9) | 81 | 12.1 (9.2, 15.6) | 92 | 11.9 (9.4, 15.1) | |||
| Definitely yes | 8 | 4.1 (1.7, 9.4) | 8 | 1.9 (0.8, 4.5) | 12 | 1.4 (0.7, 3.1) | |||
| Would try ENDS if best friend offered (punadj < .001, padj < .001) | |||||||||
| Definitely not | 33 | 12.2 (8.2, 17.7) | 176 | 31.9 (27.2, 36.9) | 306 | 35.7 (31.7, 40.0) | |||
| Probably not | 76 | 36.6 (28.7, 45.4) | 220 | 33.8 (29.1, 38.7) | 241 | 28.4 (24.7, 32.5) | |||
| Probably yes | 77 | 40.0 (31.5, 49.2) | 174 | 26.5 (22.2, 31.4) | 259 | 29.2 (25.5, 33.2) | |||
| Definitely yes | 20 | 11.1 (6.8, 17.7) | 38 | 7.8 (5.2, 11.6) | 56 | 6.6 (4.8, 9.1) | |||
ENDS = electronic nicotine delivery system; n = unweighted frequency; CI = confidence interval; CPD = cigarettes per day. Column percentages are reported. Weighted unadjusted and adjusted logistic regression models were estimated and a likelihood ratio test was performed to evaluate the association between the column variable (former/never ENDS user group) with each row variable. P-values are reported for unadjusted (punadj) and adjusted (padj) models. Adjusted models controlled for age, sex, race/ethnicity, household income, and education.
Smokers who formerly used ENDS regularly, as well as experimentally, were more likely to smoke daily (74.5% and 75.2%, respectively) compared to never ENDS users (70.1%). Among former ENDS users, former experimental ENDS users (27.9%) were less likely to indicate intentions to quit smoking within the next six months compared to their counterparts who had used ENDS regularly (38.2%). Among smokers who had used ENDS, those who never used regularly (29.8%) were most likely to have used a non-rechargeable ENDS device (vs. 9.0%) and less likely to have used a rechargeable, refillable ENDS (39.6%) compared to former regular ENDS users (71.4%).
Former regular ENDS users were more likely to believe ENDS were less harmful than smoking cigarettes (37.8%) than never (15.3%) and former experimental ENDS users (29.2%). Never (33.2%) and former experimental ENDS users (28.1%) were more likely to be uncertain than former regular users (21.7%). Most smokers believed that nicotine was definitely harmful, with only minor differences in harm perceptions of nicotine observed among the groups. Most former ENDS users reported that using ENDS was less enjoyable than smoking cigarettes, with former experimental users (82.8%) more likely to hold this believe than former regular ENDS users (71.7%). Smokers who were formerly regular users of ENDS indicated greater intentions to use them (again) soon or use them if a best friend were to offer them one than never or former experimental users.
3.2. Reasons Smokers Provided for Discontinuing ENDS
Most smokers (57.6%) who discontinued ENDS reported that the three main reasons for discontinuation were that “they didn’t feel like smoking a cigarette” (22.9%), “I only ever tried them to see what they were like” (20.3%), or “they didn’t help me deal with cravings for smoking” (14.4%) (Table 2). Also salient was concerns about their safety (10.2%).
A statistically significant association (p < .003) was observed between regularity of former ENDS use and reasons cited for no longer using ENDS, adjusting for covariates. Whereas regular and experimental former users similarly endorsed the reasons that use of ENDS did not feel like smoking (23.0% and 22.5%, respectively) and that ENDS did not satisfy their cravings for smoking (13.2% and 17.9%, respectively), experimental users were more than four times more likely to cite that they only tried ENDS out of curiosity than those who had used ENDS regularly (25.2% vs. 5.8%). In contrast, those who had used ENDS regularly were more likely to endorse the reasons that they felt they were “using them too often compared with smoking” (9.4% vs. 3.0%).
Differences were also observed depending on which type of ENDS device they had primarily used (p < .001). Former users of non-rechargeable ENDS were much more likely to say they did not feel like smoking a cigarette (34.2%) than rechargeable, refillable ENDS users (24.0%) and non-rechargeable users (18.8%). In comparison, former non-rechargeable ENDS users were more likely to indicate they only tried them out of curiosity (25.2%) than rechargeable, refillable ENDS users (12.8%).
3.3. Reasons Smokers Provided for Not Trying ENDS
Overall, most smokers who have not tried ENDS stated as reasons that they did not want to substitute one addiction for another (60.0%), concern about their safety (52.7%), or skepticism that ENDS could help them quit or cut down on smoking (52.0%) (see Table 3). (Smokers could select more than one reason.) Nearly as many cited concerns about their cost (42.8%).
Compared to smokers with weaker quit intentions, those smokers with intentions to quit during the next 6 months were more likely to indicate that they did not want to substitute one addiction for another (68.9% vs. 55.7%), doubts of their effectiveness for helping them quit or reduce their smoking (55.7% vs. 50.5%), that they were not safe enough (61.5% vs. 48.3%), and that they were using other approaches for quitting smoking (28.8% vs. 9.2%). Compared to adults over age 30, young adult smokers (18–29 years) were significantly more likely to endorse that they “haven’t gotten around to” using them yet (39.7% vs. 25.4%).
Smokers who perceived ENDS as more harmful than cigarettes were much more likely to cite concerns about their safety compared to those who perceived ENDS as less harmful or were uncertain about their relative harm (74.5% vs. 46.9% or 48.6%) (Table 4). Conversely, smokers who perceived ENDS as less harmful were approximately twice as likely to cite as a reason that they “haven’t gotten around to it yet” compared to those that perceived the same level of risk or were uncertain about relative risk (45.4% vs. 17.7% or 25.3%).
Table 4.
The reasons US adult current smokers provide for never having tried or used ENDS stratified by the perceived relative harm of ENDS (2017–2018)
| Perceived Relative Harm of ENDS | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Less harmful than cigarettes | About the same harm | More harmful than cigarettes | I don’t know | |||||||||
| n | Weighted % (95% CI) | n | Weighted % (95% CI) | n | Weighted % (95% CI) | n | Weighted (95% CI) % | p | ||||
| I do not want to substitute one addiction for another | 80 | 55.7 (45.2, 65.7) | 240 | 62.8 (55.8, 69.3) | 46 | 56.2 (42.0, 69.4) | 179 | 60.4 (52.9, 67.5) | (.64, .030) | |||
| I am concerned they are not safe enough | 62 | 46.9 (36.5, 57.5) | 211 | 53.4 (46.6, 60.1) | 57 | 74.5 (60.8, 84.7) | 158 | 48.6 (41.3, 56.0) | (.004, < .001) | |||
| I do not think they would help me to quit or cut down | 68 | 46.5 (36.2, 57.1) | 205 | 55.5 (48.7, 62.0) | 39 | 53.0 (39.4, 66.2) | 163 | 50.7 (43.2, 58.0) | (.53, .063) | |||
| They cost too much | 62 | 45.7 (35.3, 56.3) | 144 | 42.9 (36.4, 49.8) | 37 | 43.8 (31.1, 57.4) | 117 | 41.3 (34.3, 48.7) | (.93, .23) | |||
| I do not want to quit smoking | 43 | 39.4 (29.1, 50.8) | 123 | 36.3 (30.0, 43.2) | 27 | 28.7 (18.8, 41.2) | 98 | 33.4 (26.8, 40.8) | (.57, .16) | |||
| There are too many products to choose from | 57 | 40.4 (30.5, 51.1) | 100 | 26.4 (21.0, 32.5) | 26 | 34.6 (23.1, 48.2) | 105 | 34.7 (28.1, 41.9) | (.083, .014) | |||
| I haven’t gotten around to it yet | 67 | 45.4 (35.2, 56.0) | 87 | 24.2 (18.7, 30.8) | 12 | 17.7 (9.6, 30.2) | 73 | 25.3 (19.5, 32.2) | (< .001, < .001) | |||
| I do not like the way they look | 38 | 29.8 (20.6, 41.0) | 94 | 24.5 (19.3, 30.5) | 24 | 27.6 (17.6, 40.5) | 74 | 21.3 (16.3, 27.2) | (.43, .17) | |||
| I am not addicted to smoking and don’t need help to quit | 26 | 21.5 (13.6, 32.2) | 64 | 19.7 (14.7, 26.0) | 24 | 27.9 (17.9, 40.9) | 51 | 16.5 (12.0, 22.3) | (.33, .12) | |||
| I am using other things to help me quit smoking | 25 | 16.9 (10.1, 27.1) | 69 | 16.7 (12.5, 21.8) | 17 | 18.2 (10.5, 29.6) | 52 | 13.5 (9.7, 18.5) | (.76, .42) | |||
| I would be embarrassed to use them in public | 25 | 21.6 (13.2, 33.5) | 63 | 17.6 (13.2, 23.2) | 16 | 18.6 (10.6, 30.5) | 46 | 12.9 (9.3, 17.6) | (.31, .46) | |||
| They are too difficult to get hold of | 9 | 8.1 (3.2, 19.1) | 29 | 6.5 (4.3, 9.9) | 11 | 16.1 (8.5, 28.5) | 29 | 11.0 (7.3, 16.3) | (.14, .10) | |||
| Other | 11 | 5.4 (2.6, 10.7) | 23 | 7.4 (4.6, 11.8) | 2 | 3.9 (0.9, 15.1) | 17 | 5.3 (3.0, 9.1) | (.71, .67) | |||
ENDS = electronic nicotine delivery system; n = unweighted frequency; CI = confidence interval. Column percentages are reported for each reason. Participants could select multiple reasons. Weighted unadjusted and adjusted logistic regression models were estimated and a likelihood ratio test was performed to evaluate the association between the column variables (perceived relative harm of ENDS vs. cigarettes) with each row variable (reason for never having tried or used ENDS). P-values are reported for unadjusted (punadj) and adjusted (padj) models. Adjusted models controlled for age, sex, race/ethnicity, household income, education, and smoking quit intentions. Statistically significant effects (p < .05) are denoted by boldface p-values.
4. DISCUSSION
The findings of this study provide important, more recent insights into the reasons U.S. smokers give for their discontinuance or never use of ENDS and have implications for policies and regulations aimed at optimizing their potential for harm reduction. In this study, more than 70% of current smokers had either never used or discontinued using ENDS while continuing to smoke. While the question whether these smokers represent a missed opportunity for harm reduction depends on whether ENDS are effective for quitting, the reasons these smokers provided may indicate why previous studies have not found ENDS to be effective for quitting under real-world use conditions (Halpern et al., 2018; Rigotti et al., 2018; Sweet et al., 2019; Weaver et al., 2018).
Not satisfactorily replicating the “feel” of smoking or reducing their cravings to smoke were the primary reasons that 37% of current smokers who formerly used ENDS gave for discontinuing them, particularly by smokers who had used rechargeable, non-refillable system ENDS. Indeed, more than 75% of these smokers reported that using ENDS was less enjoyable than smoking cigarettes. These reasons were also commonly reported by UK smokers, a multinational sample that included some US smokers, and earlier studies of US smokers and are consistent with research indicating that ENDS generally have not delivered nicotine comparably to cigarettes (Action on Smoking and Health, 2016; Biener et al., 2015; Farsalinos et al., 2018; Hajek et al., 2017; Yong et al., 2019). In contrast to two earlier US-based studies (Biener et al., 2015; Biener and Hargraves, 2015), the current study did not find cost or malfunction to be dominant reasons. Although curiosity was also a prevalent reason, it was mostly endorsed by smokers who only used ENDS experimentally – most of these former ENDS users – or smokers who had used non-rechargeable ENDS (the least used device type). A UK survey also reported curiosity has the second most endorsed reason for no longer using ENDS (Action on Smoking and Health, 2016). Non-rechargeable (disposable) ENDS typically have a cigarette-like appearance, are generally sold where smokers would purchase cigarettes, and have lower upfront costs than rechargeable e-cigarettes, which might make them more attractive to smokers who are merely curious to try them (Braak et al., 2019; Grana et al., 2014; Liber et al., 2017; Sussman and Barker, 2017). Smokers who had used ENDS regularly, on the other hand, were more likely than experimental former users to endorse that they were using them too often as reasons for their discontinuation. Disposable and rechargeable, closed-system ENDS are likely to be easier to use, but they were less likely to provide comparable delivery of nicotine relative to rechargeable, refillable systems (Farsalinos et al., 2018; Hajek et al., 2017). Smokers who had used these ENDS regularly may have had to use them more frequently than they had to smoke cigarettes in order to satisfy their cravings. However, this is likely to change with the rising use of JUUL and other similar ENDS that use nicotine-salts and higher nicotine concentrations that deliver nicotine comparable to the refillable ENDS and cigarettes such that smokers may no longer need to use these newer ENDS more frequently to satisfy their cravings (Goniewicz et al., 2018; Huang et al., 2019a; Talih et al., 2019). These former regular ENDS users may also have been using ENDS in situations in which they could not smoke cigarettes. To a lesser extent, though at levels twice that of UK smokers, concerns about their safety were also reported (Simonavicius et al., 2017). Less than 40% of former regular ENDS users and less than 30% of former experimental ENDS users believed ENDS were less harmful than smoking cigarettes. The difference with UK smokers may stem from more prevalent perceptions in the US that ENDS are equally or more harmful than cigarettes and differences in media coverage and messaging from public health and medical organizations in the two countries (Huang et al., 2019b; Wackowski et al., 2019; Wilson et al., 2019). That 33% of former users who had used regularly would probably or definitely try ENDS soon (51% would probably or definitely try if offered by a best friend) indicates that this group has not completely rejected ENDS and is open to future use. Former experimental users were less open to trying ENDS in the future (14% said they would probably or definitely try soon), though at least one-third would probably or definitely try them if offered by a friend.
Whereas current smokers who had formerly used ENDS largely cited reasons of inadequate craving reduction or incomparability to smoking for their discontinuation, the larger segment of current smokers who have never used ENDS cited different reasons for non-use, namely concerns about substituting one addictive product for another, perceived ineffectiveness for quitting smoking, and concerns about their safety. Indeed, these smokers were less likely to perceive ENDS as less harmful than smoking and more likely to be uncertain about the relative harms than former, regular ENDS users. In addition, most of these smokers perceived nicotine as definitely harmful to adults, which might explain their reluctance to substitute one addictive product (ENDS) for another (cigarettes) and concerns about the safety of ENDS. That smokers with stronger quit intentions were also more likely to cite as a reason that they were using other methods for quitting smoking might suggest that they perceived ENDS to be less effective and/or less safe relative to other quit approaches and may have a stronger motivation to cease their nicotine addiction. While these smokers have no direct experience using ENDS, their perceptions of their safety (or lack of) could be explained by the media coverage and public health messaging on ENDS (Wackowski et al., 2018, 2015). Similarly, the medical and public health organizations have been cautious, if not resistant, to endorse ENDS for smoking cessation as the US-based research on their effectiveness has been mixed, if not generally negative; and this too has received extensive media coverage (Bhatnagar et al., 2019; Douglas et al., 2018; National Academies of Sciences, Engineering, and Medicine, 2018). Concerns about substituting one addiction for another was the most commonly endorsed reason for not trying ENDS. Perhaps for these smokers, particularly those with greater quit intentions, the best approach may be to help them quit rather than encourage them to switch to ENDS. The perceived financial cost of ENDS was also cited as a reason for not using them. While the long-term costs of ENDS are generally lower than smoking, their initial costs are often greater (Cantrell et al., 2018; Wang et al., 2018). Taxation and other policies that increase the cost to purchase ENDS may deter their use among smokers who have not yet used them (Huang et al., 2018).
4.1. Limitations
The data used in this study are based on a cross-sectional, self-report study and may be subject to recall biases and inaccuracies, and shared-method variance bias. Causality cannot be inferred from the correlational data. This study did not assess the nicotine concentration used by former ENDS users, which might have influenced smokers’ experiences and decisions to discontinue using ENDS. In addition, the relatively few young adult smokers that had not tried ENDS limited the statistical power available for tests comparing the reasons reported by young adults with older adults. Furthermore, this study was conducted prior to the outbreak of EVALI (electronic cigarette or vaping associated lung injury). It is plausible that concerns about ENDS safety have become more salient for smokers and a reason for their non-use of ENDS.
4.2. Implications
To the extent that exclusive use of ENDS by current smokers may be less harmful than smoking cigarettes, achieving ENDS’ potential for harm reduction would require that they are sufficiently appealing to smokers to initiate and continue using them in complete replacement of smoking cigarettes. Needed is research to better understand the conditions under which ENDS are effective for craving reduction and smoking cessation. Regulations and policies could help ensure that the ENDS on the market yield comparable nicotine delivery to cigarettes while allowing manufacturers to improve aspects that matter to smokers and enhance their substitutability for cigarettes. Education and communication efforts could help smokers understand the conditions in which ENDS can be more effective for quitting and inform them of the relative and absolute risks. Regulatory and communication strategies that encourage their use for harm reduction will need careful design and evaluation to guard against sustained dual use or unintended consequences, particularly use by youth, never smokers, or long-term former smokers. Recent increases in youth ENDS use and high rates of dual use, along with the difficulties of effectively communicating absolute and relative risks of ENDS to smokers without unintended consequences, represent some of the major challenges in achieving population harm reduction with ENDS (Gentzke et al., 2019; Miech et al., 2019; Weaver et al., 2018).
Supplementary Material
Highlights.
Over 30% of smokers have tried and discontinued e-cigarettes
Inadequate craving reduction and incomparability to smoking are key reasons
Nearly 40% of smokers have not tried e-cigarettes
Concerns about addiction, safety, and effectiveness were key reasons for non-use
E-cigarette type, perceptions, and other factors were associated with reasons
ACKNOWLEDGEMENTS
This work was supported by the National Institute on Drug Abuse and the FDA Center for Tobacco Products (P50DA036128). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH or the FDA.
Role of Funding Source
This work was supported by the National Institute on Drug Abuse and the Food and Drug Administration (FDA) Center for Tobacco Products (CTP) (grant number P50DA036128). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH or the Food and Drug Administration. The funding agencies had no involvement in the study design; collection, analysis and interpretation of the data; writing of this report; or in the decision to submit the article for publication.
Conflict of Interest
Dr. Michael Eriksen received unrestricted research funding support from Pfizer, Inc. (“Diffusion of Tobacco Control Fundamentals to Other Large Chinese Cities” Michael Eriksen, Principal Investigator). David L. Ashley has received funds for work done for the World Health Organization Tobacco Free Initiative, as a Special Government Employee of the U.S. Food and Drug Administration, as a consultant for Pfizer, and as an independent contractor for McKing Consulting. No financial disclosures were reported by the other authors of this paper. The authors declare that there are no other financial relationships with any organizations that might have an interest in the submitted work, and there are no other relationships or activities that could appear to have influenced the submitted work.
Footnotes
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