Trends in E-Cigarette, Cigarette, Cigar, and Smokeless Tobacco Use Among US Adolescent Cohorts, 2014–2018

Abstract

Objectives. To examine changes in age of initiation of e-cigarette, cigarette, cigar, and smokeless tobacco use among adolescents in the United States.

Methods. We used data from 5 cohorts of the National Youth Tobacco Survey (2014–2018; n = 26 662).

Results. In 2014, 8.8% of lifetime e-cigarette users initiated use at 14 years or younger, as compared with 28.6% of lifetime e-cigarette users in 2018. There was no such change in initiation ages for cigarettes, cigars, and smokeless tobacco among lifetime users of each of these products.

Conclusions. US adolescents are initiating e-cigarette use at younger ages in recent years. This is concerning given the association of e-cigarette use with subsequent cigarette use. Continued surveillance of these trends and additional prospective research are needed. Tobacco prevention programs, policies, and regulations that make it more difficult for youths to obtain e-cigarettes are warranted.

E-cigarette use has increased among adolescents in the United States over the past decade, with more than 1 in every 10 US high school students reporting past-month use.^1,2 Data from 2014 demonstrate e-cigarette initiation beginning as early as 7 years, with a mean age of 17.5 years.³ Despite this concerning increase in e-cigarette use since the introduction of e-cigarettes to the US market in the mid-2000s,⁴ there remains a gap in knowledge regarding whether age at initiation of e-cigarette use is changing.

The literature demonstrates the risks associated with early initiation of cigarettes, including later dependence, difficulty quitting, risk for other substance use,^5–7 and physical health risks including lung damage.⁸ Less research to date has focused on age at initiation of e-cigarette use. One study showed that early use was associated with an increased risk of subsequent cigarette use.⁹

Although the increasing prevalence of e-cigarette use is well documented, no studies to our knowledge have examined whether age at initiation of e-cigarette use has changed across time and how changes in initiation of e-cigarettes compares with changes in initiation of other tobacco products. The purpose of this study was to examine trends in age of initiation of e-cigarettes across 5 cohorts and how these trends compare with those observed for other tobacco products in a large, nationally representative sample of young people in the United States.

METHODS

The National Youth Tobacco Survey (NYTS) annually surveys a cross-sectional, nationally representative sample of middle school and high school students (6th–12th grade) in public and private schools in the United States. The NYTS involves a multistage sampling procedure at the county, school, and student levels. The average response rate for the survey is 76.2%.¹⁰

Our study focused on youths 16 and 17 years of age to (1) provide for the possibility of e-cigarette initiation beginning at 12 years old and earlier (e-cigarettes emerged in the US market when the 2014 cohort of 16- and 17-year-old youths would have been 11 and 12 years old⁴) and (2) allow all in the sample to have had the opportunity to initiate e-cigarettes through the ages of 16 and 17 years. A total of 26 662 youths 16 and 17 years old participated in the NYTS between 2014 and 2018. Each trend analysis was restricted to those reporting lifetime use of the relevant tobacco product (8918 e-cigarette users, 7936 cigarette users, 6639 cigar users, 2946 smokeless tobacco users). The sample was 49.9% male and 67.1% White, and was evenly split between youths 16 (51.5%) and 17 (48.5%) years old. Given that age at first e-cigarette use was introduced to the NYTS in 2014, we used this year as the starting point for assessing trends.

As a means of assessing age at first e-cigarette, cigarette, cigar, and smokeless tobacco use, respondents were asked “How old were you when you first tried [an e-cigarette, cigarette smoking, cigars/cigarillos/little cigars, chewing tobacco/snuff/dip], even once or twice?” The response options ranged from 8 years or younger to 19 years or older. Age categories were recoded as 12 years or younger, 13 years, 14 years, 15 years, 16 or 17 years, and never used. The results reported here focus on those initiating use at 14 years or younger and 16 or 17 years.

We used design-based χ² tests to examine age at initiation among lifetime users of e-cigarettes, cigarettes, cigars, and smokeless tobacco across 5 age cohorts. The analyses included weights to account for the complex 3-stage sample design. When estimating standard errors, we used specialized variance estimation techniques to accommodate complex sample design features.¹⁰

RESULTS

Figure 1 shows ages at initiation of use among lifetime users of e-cigarettes, cigarettes, cigars, and smokeless tobacco for each of the 5 cohorts from 2014 to 2018. Among lifetime e-cigarette users, 63.0% initiated use at 16 or 17 years old in 2014, as compared with 42.7% in 2018. Conversely, 8.8% and 28.6% of lifetime e-cigarette users initiated use at 14 years or younger in 2014 and 2018, respectively. The difference in initiation of e-cigarette use between age cohorts was statistically significant (χ² = 17.46; P < .001).

FIGURE 1—

Age of Tobacco Use Initiation Among Current 16- to 17-Year-Old Lifetime Users by Cohort Year for (a) E-Cigarettes, (b) Cigarettes, (c) Smokeless Tobacco, and (d) Cigars: United States, National Youth Tobacco Survey (NYTS), 2014–2018

Note. The overall sample size was 26 662. E-cigarette users, n = 8918; cigarette users, n = 7936; cigar users, n = 6639; smokeless tobacco users, n = 2946. Prevalence values for earliest and latest years are labeled. All analyses are weighted to adjust for the NYTS sampling design.

By comparison, there were no significant cohort differences in age of initiation of cigarette use (χ² = 1.62; P = .077), cigar use (χ² = 0.985; P = .464), or smokeless tobacco use (χ² = 1.30; P = .212). Among lifetime cigarette users in particular, 55.8% initiated cigarette use at 14 years or younger in 2014, as compared with 51.3% in 2018.

DISCUSSION

This study examined age at initiation of e-cigarette use versus use of other tobacco products in cohorts of 16- and 17-year-old lifetime tobacco users from 2014 to 2018. We found that age of initiation of e-cigarette use was younger among more recent cohorts. Thus, not only are more youths reporting e-cigarette use,^1,2 but they are also beginning to use e-cigarettes at earlier ages.

Importantly, this decline in age of initiation was specific to e-cigarettes; we did not see differences for cigarettes, cigars, or smokeless tobacco products. These differing trends could reflect the longer existence of other tobacco products in the market and the consistent proportion of younger adolescents initiating use of these other products relative to e-cigarettes. Although we did not see significant cohort differences in age of initiation of other tobacco products, early initiation of cigarette use remains an endemic problem, with more than one quarter of cigarette users starting by 12 years of age. Data from the Monitoring the Future survey show that cigarettes are still the first product used by most tobacco (cigarette and e-cigarette) dual users, but the proportion of adolescents who begin with e-cigarettes is increasing.¹¹ Taken together, trends toward earlier initiation of e-cigarette use, e-cigarettes increasingly serving as a starter tobacco product, and increases in adolescent e-cigarette use prevalence signal a significant public health concern.

The earlier initiation of e-cigarette use in the most recent cohorts of adolescents is particularly alarming given research showing that early initiation of e-cigarettes is associated with a subsequent risk for cigarette use.⁹ Nicotine exposure earlier in development, when the brain is continuing to mature, may confer particular risk.¹² Recent reports linking e-cigarettes to respiratory illnesses add to the health concerns of early e-cigarette use (see http://bit.ly/2mscQff for the recent Food and Drug Administration [FDA] press release). Future research should examine how early e-cigarette use is associated with subsequent tobacco use and health risks in adulthood and whether recent federal actions enforcing regulation of flavored tobacco products will influence these trends of earlier use (see http://bit.ly/2ksVuhI for the FDA announcement).

This study has limitations, including a reliance on self-reported data and omission of some tobacco products (e.g., hookah products). Also, given the cross-sectional nature of the data, we relied on retrospective reports of age of initiation, introducing the potential for recall bias.

Ongoing surveillance of these initiation trends is warranted to monitor whether age at initiation continues to decrease. Given our findings, tobacco prevention programs addressing e-cigarette use may need to tailor risk communications and policy efforts to youths of younger ages to deter initiation.

PUBLIC HEALTH IMPLICATIONS

Public policies that restrict access to e-cigarettes and e-liquids and denormalize their use should be paramount priorities given the increasing number of adolescents initiating use early.