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Original research
Age of tobacco use initiation and association with current use and nicotine dependence among US middle and high school students, 2014–2016
  1. Saida Sharapova1,
  2. Carolyn Reyes-Guzman2,
  3. Tushar Singh1,3,
  4. Elyse Phillips1,
  5. Kristy L Marynak1,
  6. Israel Agaku1
  1. 1 Office on Smoking and Health, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
  2. 2 Division of Cancer Control and Population Sciences, National Cancer Institute, National Institutes of Health, Rockville, Maryland, USA
  3. 3 Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
  1. Correspondence to Dr Saida Sharapova, Office on Smoking and Health, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta GA 30341, USA; ssharapova{at}cdc.gov

Abstract

Introduction Tobacco use mostly begins in adolescence and young adulthood. Earlier age of initiation of cigarette smoking is associated with greater nicotine dependence and sustained tobacco use. However, data are limited on the age of initiation of non-cigarette tobacco products, and the association between using these products and nicotine dependence and progression to established use.

Methods Combined 2014–2016 National Youth Tobacco Survey data, a nationally representative cross-sectional survey of US students in grades 6–12 yielded 19 580 respondents who reported ever using any of five tobacco products: electronic cigarettes, cigarettes, cigars, smokeless tobacco and hookah. Analyses assessed age of reported first use of each product among ever-users, overall and by sex and race/ethnicity. Current daily use, past 30-day use, feelings of craving tobacco and time to first tobacco use after waking were assessed by age of first use.

Results Among ever-users, weighted median age for first use was 12.6 years for cigarettes, 13.8 years for cigars, 13.4 years for smokeless tobacco, 14.1 years for hookah and 14.1 years for e-cigarettes. First trying these tobacco products at age ≤13 years was associated with greater current use of the respective product and nicotine dependence compared with initiating use at age >13 years.

Conclusions First tobacco use at age ≤13 years is associated with current daily and past 30-day use of non-cigarette tobacco products, and with the development of nicotine dependence among youth ever-users. Proven tobacco prevention interventions that reach early adolescents are important to reduce overall youth tobacco use.

  • surveillance and monitoring
  • non-cigarette tobacco products
  • addiction

http://dx.doi.org/10.1136/tobaccocontrol-2018-054593

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    Introduction

    Tobacco use and nicotine dependence usually begin in adolescence and young adulthood, and can lead to serious health, social and economic consequences.1–4 Earlier age of cigarette smoking initiation is independently associated with establishing daily smoking and nicotine dependence, and nicotine dependence in adolescents can develop soon after first trying a cigarette.5–7 Additionally, smoking initiation in early adolescent (10–13) years compared with late adolescent age may be associated with different psychosocial risk factors and greater consequences.8–12 To date, there is no established threshold for early versus late age of initiation among adolescents in the published literature.8–12

    Adolescents report consuming a variety of tobacco products besides cigarettes. In 2017, an estimated 3.62 million US middle and high school students reported using a tobacco product on at least 1 day in the past 30 days, and 1.66 million reported use of ≥2 tobacco products in the same period.13 Electronic cigarettes (‘e-cigarettes’) were used most commonly, followed by cigarettes and cigars, smokeless tobacco and hookah.13

    To date, research on age of initiation of non-cigarette tobacco products among US adolescents has been limited by assessing initiation of e-cigarette use, but not initiation of other tobacco products.3–5 7 8 14–19 To address this gap, we used a nationally representative sample of US youth to assess the age of initiation of five categories of tobacco products: e-cigarettes, cigarettes, cigars, smokeless tobacco and hookah. We also examined whether trying each of these tobacco products for the first time in early adolescent years was a risk factor for current use of the product (daily or any use in past 30 days) and for other measures of nicotine dependence (craving or need for tobacco and time to first use of tobacco (TTFT) in the morning). This study is the first to report age of initiation of cigars, smokeless tobacco and hookah among US middle and high school students.

    Methods

    Data source

    For this study, we used the National Youth Tobacco Survey (NYTS), an annual pencil-and-paper cross-sectional survey. NYTS has a stratified, three-stage cluster sample design and produces a nationally representative sample of US public and private school students in grades 6–12 in 50 states and the District of Columbia. NYTS collects data on tobacco-related beliefs, attitudes, behaviours, exposure to pro-tobacco and anti-tobacco influences and demographic correlates.20

    We combined data from the 2014 (n=22 007, overall response rate 73.3%), 2015 (n=17 711, overall response rate 63.4%) and 2016 (n=20 675, overall response rate 71.6%) surveys. Analyses of our combined sample of 60 393 participants included 19 580 respondents (our analytic sample) who reported ever using at least one of the following five tobacco product categories: e-cigarettes, cigarettes, cigars, smokeless tobacco and hookah and age of the first use of these products. Age of first trying hookah was only available in 2016 data, where 2140 students reported ever using this product. NYTS did not collect information on the age of the first trial of pipes filled with tobacco (not water pipes), bidis (small brown cigarettes wrapped in a leaf), snus or dissolvable tobacco products; therefore, these products were not assessed in this analysis.

    Measures

    We assessed five categories of tobacco products: electronic cigarettes (‘e-cigarettes’); cigarettes; cigars, cigarillos or little cigars (‘cigars’); chewing tobacco, snuff or dip (‘smokeless tobacco’); and hookah or water pipes used with tobacco (‘hookah’).

    We defined initiation as first use of the product, based on the following questions: ’How old were you when you first tried [cigarette smoking/smoking a cigar, cigarillo or little cigar/smoking tobacco in a hookah or waterpipe], even one or two puffs?’ ‘How old were you when you used chewing tobacco, snuff or dip for the first time?’ and ‘How old were you when you first tried using an e-cigarette, even once or twice?’ Answer choices included ‘I have never used [product],’ ‘8 years old or younger', ‘19 years old or older’ and whole years between ages 9 and 18.

    For each tobacco product category, we examined outcomes of ever use, current use and nicotine dependence. Ever users were those who reported ever trying these tobacco products. Current use outcomes included daily use (use of a tobacco product on all 30 days) and past 30-day use (use of a tobacco product on at least 1 day in the past 30 days) compared with no use in the past 30 days. Nicotine dependence was assessed by two measures. First, positive compared with negative response to question ‘During the past 30 days, have you had a strong craving of felt like you really needed to use a tobacco product of any kind?’ Second, TTFT≤30 min after waking compared with >30 min as assessed by question ‘How soon after you wake up do you want to use a tobacco product?’6 21 22

    Demographic characteristics included sex (male and female) and race/ethnicity. Race and ethnicity were self-identified based on two questions and were recoded into four categories: non-Hispanic white, non-Hispanic black, Hispanic and non-Hispanic ’other’. Non-Hispanic ‘other’ category included non-Hispanic American Indian or Alaska Native, non-Hispanic Asian and non-Hispanic Native Hawaiian or Other Pacific Islander categories whose sample sizes were too small for separate analyses.

    Analysis

    For descriptive analyses, we calculated distribution of the reported age of first use among ever-users by product, weighted proportions and 95% CIs for self-reported (1) ever use, (2) daily use and (3) past 30-day use for each tobacco product category among all survey respondents. For the reported age of first use of each tobacco product, we assessed overall weighted median and IQR. For estimating differences by sex and race/ethnicity, we used abridged mean age of initiation (9–18 years) to allow for analysis of variance (ANOVA) with post-hoc Tukey tests.

    We used 20 unadjusted and adjusted logistic regression models to examine if age of initiation was associated with current use and nicotine dependence for the five assessed tobacco products (4 outcomes for each of the 5 products). Age of first trying a tobacco product was dichotomised as ≤ 13 and >13 years. The median age of cigarette initiation in NYTS data, 13 years, resulted in more precise estimates in unadjusted and adjusted regression models compared with other cut-off points of 11, 12, 14 and 15 years. Adjusted models controlled for sex, race/ethnicity, current age, survey year and current use of other tobacco products (e-cigarettes, cigarettes, cigars, smokeless tobacco, pipes filled with tobacco, hookah or a water pipe used with tobacco, bidis, snus, roll-your-own cigarettes or dissolvable tobacco products). Current use of other tobacco products was defined as a composite variable for using any tobacco product besides the one being tested on at least 1 day in the past 30 days.

    Results

    Descriptive statistics

    In our pooled sample of 60 393 US middle and high school students, 22.8% (95% CI 21.5% to 24.0%) reported ever using e-cigarettes, 21.0% (95% CI 19.8% to 22.1%) reported ever using cigarettes, 15.9% (95% CI% 14.9 to 16.9%) reported ever using cigars, 7.8% (95% CI 7.0% to 8.6%) reported ever using smokeless tobacco, and 9.9% (95% CI 8.8% to 10.9%) reported ever using hookah (percentages non-mutually exclusive, online supplementary table 1). Additionally, past 30-day and daily use, respectively, were reported in the following proportions among all respondents: 9.6% (95% CI 8.9% to 10.4%) and 1.0% (95% CI 0.9% to 1.2%) for e-cigarettes, 6.0% (95% CI 5.5% to 6.5%) and 1.3% (95% CI 1.1% to 1.4%) for cigarettes, 5.4% (95% CI 5.0% to 5.9%) and 0.6% (95% CI 0.5% to 0.7%) for cigars, 3.6% (95% CI 3.1% to 4.1%) and 1.0% (95% CI 0.8% to 1.2%) for smokeless tobacco, and 5.0% (95% CI 4.5% to 5.4%) and 0.6% (95% CI 0.4% to 0.7%) for hookah.

    Among the five tobacco product categories studied, the median age of initiation was lowest for cigarettes (weighted median 12.6 years, IQR 10.6–14.4 years), followed by smokeless tobacco (weighted median 13.4 years, IQR 11.3–14.9 years), cigars (weighted median 13.8 years, IQR 12.1–15.2 years), hookah (weighted median 14.1 years, IQR 12.4–15.3 years) and e-cigarettes (weighted median 14.1 years, IQR 12.6–15.4 years) (table 1). Figure 1 presents the age of initiation distribution for the five tobacco product categories studied. Among tobacco ever-users, between 1.4% (e-cigarettes) and 10.3% (cigarettes) of the students reported trying tobacco for the first time at age 8 years or earlier. Reported first use of all five tobacco products studied dropped steeply after age 16 years (figure 1).

    View this table:
    Table 1

    Age of initiation for users of five tobacco products among US middle and high school students, National Youth Tobacco Survey, 2014–2016 (n=19 580)

    Figure 1
    Figure 1

    Percentage of US middle and high school students who used a tobacco product for the first time, by age and tobacco product category; National Youth Tobacco Survey, 2014–2016.

    Overall, adolescent tobacco users reported first trying tobacco products at ≤13 years in the following proportions: e-cigarettes 30.0% (95% CI 27.7% to 32.4%), cigarettes 55.4% (95% CI 53.5% to 57.3%), cigars 35.6% (95% CI 33.6% to 37.7%), smokeless tobacco 44.2% (95% CI 41.0% to 47.5%) and hookah 33.3% (95% CI 28.9% to 37.7%) (table 1).

    Age of initiation by sex and race/ethnicity

    Compared with females, males reported a slightly younger age of initiation of e-cigarettes, cigarettes, cigars and hookah, and a slightly older age of initiation of smokeless tobacco. The differences were ≤0.1 year and were statistically significant for cigars but not for other tobacco products (table 1). There were statistically significant differences by race and ethnicity in the reported age of first trying tobacco products. Non-Hispanic black, Hispanic and non-Hispanic students who did not self-identify as white or black (ie, non-Hispanic ‘other’) reported first trying tobacco products at younger ages compared with non-Hispanic white students (table 1).

    Multivariable findings

    The odds of past 30-day use were increased among adolescent ever-users who reported first trying cigarettes, cigars, smokeless tobacco or hookah at ≤13 years compared with first trying at age >13 years in the models fitted for each product respectively and adjusted for current age, sex, race/ethnicity, survey year and current use of other tobacco products (table 2). Similarly, first trying each of the five tobacco products at age ≤13 years increased the odds of daily use of the respective product in the past 30 days.

    View this table:
    Table 2

    Association between age of initiation (≤ 13 vs >13 years) on past 30-day use and tobacco dependence symptoms by tobacco product category, National Youth Tobacco Survey, 2014–2016

    In similar models, first trying any of the five tobacco products at age ≤13 years also increased the odds of experiencing tobacco cravings among adolescent ever-users of those products. First trying cigarettes, cigars, smokeless tobacco or hookah at ≤13 years increased the odds of a reported TTFT within 30 min after waking in the morning. The magnitude of the association for cigars was similar to that for cigarettes, while estimates for hookah were similar to that for smokeless tobacco; however, the association with e-cigarettes was not statistically significant (table 2).

    Discussion

    The findings from this study reveal that the majority of middle and high school students in the USA who have ever used e-cigarettes, cigars, smokeless tobacco and hookah reported first trying the products before age 16 years. The median age for first trying cigarettes was 12.6 years, 13.4 years for smokeless tobacco, 13.8 years for cigars, and 14.1 years for both hookah and e-cigarettes. The average age of initiation of these products was similar and only slightly higher than that of cigarettes. Additionally, first trying cigarettes, cigars or smokeless tobacco at ≤13 years was associated with using tobacco within 30 min of waking up in the morning and feeling strong craving or need to use tobacco of any kind in the past 30 days.

    For cigarette smoking, our results align with longitudinal studies that found the majority of adolescent cigarette smokers first experiment with cigarettes by age 16 years.23 24 In the present study, the average age of first trying cigarettes was younger than the average age of first trying e-cigarettes, cigars, smokeless tobacco or hookah, though we did not assess the statistical significance of these differences as the tobacco product categories were not independent. E-cigarette ever-users reported an older age of first trying compared with the other four products, which may reflect the relative novelty of e-cigarettes in the tobacco market compared with other conventional tobacco products and was in line with a previous report.18

    Males and females reported trying tobacco products at similar ages. This is consistent with recent patterns of smoking in the USA, in which the prevalence of smoking is similar among men and women, and a global trend for the narrowing of the sex gap.25 26 Interestingly, we did not find a later onset of tobacco use among non-Hispanic blacks, as has been reported by other studies.27 28 One possible explanation is that our study of US youth captured a cohort of non-Hispanic blacks that are early-onset smoking initiators.8 28–30 Consequently, it is possible that our results reflect recent changes in tobacco use initiation among non-Hispanic blacks. Although statistically significant, the differences in race/ethnicity categories ranged from 0.2 to 0.8 year and might not have practical implications.

    Trying cigarettes, cigars, smokeless tobacco and hookah at age ≤ 13 years increased odds of current past 30-day and daily use of these products, after controlling for age, sex, race/ethnicity, survey year and current use of other tobacco products. Trying e-cigarettes at age ≤ 13 years increased odds of daily use controlling for the covariates. Different patterns of association between age of e-cigarette initiation and current use compared with other tobacco products may reflect differential trajectories from experimenting to continuous use and warrant further research.31

    Each product also was associated with higher odds of tobacco cravings and most were associated with shorter TTFT. Our findings suggest that adolescents, especially youth aged ≤13 years, are a priority population for tobacco prevention interventions, as most adults begin smoking before the age of 18 years.1 23 These data suggest that delaying initiation as long as possible is an important component of tobacco use prevention efforts. Delaying age of initiation is a key aspect of tobacco prevention because earlier initiation of tobacco use increases the likelihood of nicotine dependence. The developing brain in childhood and adolescence shows a high degree of neuroplasticity, or the ability to learn and respond to stimuli quickly.32–34 Exposure to nicotine at this formative stage can therefore lead to faster progression to an addicted state compared with initiation as an adult.1 Adolescents can show symptoms of dependence at relatively low levels of nicotine exposure, such as after just one cigarette, potentially leading to a lifetime of persistent tobacco use.6 35 36

    Our findings reinforce the importance of comprehensive efforts to prevent and reduce use of all tobacco products among youth, and have relevance both within and outside the USA.37 For example, a report by Marcon et al from 17 European countries called attention to increased rates of smoking initiation among youth aged 15 years or less.38 Within its comprehensive framework to reduce tobacco use across the lifespan, the WHO Framework Convention on Tobacco Control (FCTC) includes actions proven to prevent youth tobacco initiation, including tobacco product price and tax increases, 100% smokefree indoor environments, public education campaigns, advertising restrictions and restrictions on sales of tobacco products to minors.37 Rapid progress has been achieved since the FCTC took effect in 2005, and 63% of the world’s population was covered by at least one comprehensive tobacco control measure as of 2017.39 Additionally, new and promising strategies continue to be developed that may further help reduce youth tobacco product use. For example, efforts to raise and enforce the age of tobacco product sales to 21 years are gaining traction in the USA because ages 18–21 years are a critical period when adults progress from experimental to regular tobacco use.40 As of April 2018, five US states and 290 cities and counties have increased the legal age for tobacco purchases to 21 years, covering a population of nearly 81 million.41

    An implication of the present study is the importance of efforts to reach youth ages 13 years and younger through proven strategies to prevent youth initiation. Regulation of the manufacturing, distribution and marketing of tobacco products by the US Food and Drug Administration (FDA), coupled with full implementation of comprehensive tobacco control and prevention strategies at the Centers for Disease Control and Prevention-recommended funding levels could reduce youth tobacco product initiation and use. Strategies to reduce youth tobacco product use also include increasing the price of tobacco products, changing statewide or community-wide smokefree policies and norms, implementing advertising and promotion restrictions and national public education media campaigns.1 High-impact tobacco education campaigns that have broad reach and sufficient frequency can be especially effective at warning youth about the dangers of tobacco use and have been expanded considerably in recent years in the USA.39 42 Examples of youth-focused tobacco education campaigns are ‘Truth’ campaign, the ‘Smokefree Teen’ website by the National Cancer Institute and ‘The Real Cost’ campaign by the FDA.43–46

    This study has at least four limitations. First, the findings are not generalisable to US youth who are not enrolled or do not attend public or private schools (eg, being institutionalised or home-schooled). Second, the data are self-reported and subject to recall and reporting biases. Third, the cross-sectional nature of the data does not allow assessment of temporal and causal relationships between the events and our results only apply to youth who already use tobacco. Fourth, small sample sizes did not allow analyses for non-Hispanic American Indian and Alaska Native, non-Hispanic Asian and non-Hispanic Native Hawaiian or Other Pacific Islander. Nevertheless, this study showed that for ever-users of the five frequently used tobacco product categories, age of first attempt at age ≤ 13 years is a significant risk factor for the current use of the product and for nicotine-dependence symptoms, after accounting for age, sex, race/ethnicity, survey year and current tobacco use. The strengths of the study include nationally representative estimates, a large sample size and information on a variety of tobacco products.

    Conclusions

    About half of US adolescents who have ever tried cigarettes and about a third of those who have ever tried e-cigarettes, cigars, chewing tobacco or hookah had their first try by age of 13 years. First trying tobacco at ≤13 years is significantly associated with continuous daily and non-daily use, and for the development of nicotine dependence.

    FDA’s regulation of the manufacturing, distribution and marketing of tobacco products, coupled with comprehensive and sustained tobacco control and prevention efforts that focus on avoiding tobacco experimentation among pre-teens and teenagers, is critical for preventing and reducing youth tobacco use. A comprehensive approach to youth tobacco prevention includes high-impact tobacco education campaigns that warn about the dangers of all forms of tobacco product use among youth.1

    What this paper adds

    What is already known on this subject

    • Tobacco use and nicotine addiction usually begin in adolescence and young adulthood; earlier age of smoking initiation is associated with establishing daily smoking and nicotine dependence.

    • In 2017, 1 in 5 US high school students and 1 in 16 middle school students reported using a tobacco product on at least 1 day in the past 30 days, including non-cigarette products such as electronic cigarettes, hookah, smokeless tobacco and cigars.

    What important gaps in knowledge exist on this topic

    • Data on the age of initiation of non-cigarette tobacco products among US adolescents are limited to reported mean age of electronic cigarette initiation and its association with subsequent initiation of cigarette smoking.

    What this paper adds

    • Adolescents who use e-cigarettes, cigars, smokeless tobacco and hookah initiate the use of these products between ages 13–14 years, on average, versus 12.6 years for cigarettes.

    • Up to three quarters of youth ever-users of e-cigarettes, cigars, smokeless tobacco and hookah reported first trying the products before age 16 years.

    • First trying tobacco products at age 13 years or younger, compared with first trying at 14 years or older, was associated with greater current use of the respective product; and two major symptoms of nicotine dependence: tobacco cravings and using tobacco within 30 min of waking up in the morning.

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    Footnotes

    • Contributors All authors have substantially contributed to the conception of the work, interpretation of data for the work and drafting and critical revisions of the work for important intellectual content; have approved the final version for publication and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. SS has analysed the data and has full responsibility for the work and decision to publish.

    • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

    • Disclaimer The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

    • Competing interests None declared.

    • Patient consent Not required.

    • Provenance and peer review Not commissioned; externally peer reviewed.