INTRODUCTION

Heated tobacco products (HTPs) are electronic devices that heat tobacco-filled sticks wrapped in paper to generate a nicotine-containing aerosol^1,2. There are a number of different HTPs that vary by mechanism and heating source, including carbon-heated tobacco products (CHTPs) that use carbon sources for heating³, and electronic HTPs that use an electrical heating source^4,5. Since 2014, several tobacco companies including Philip Morris International, British American Tobacco, RJ Reynolds Tobacco, and Japan Tobacco International, have been aggressively marketing their HTPs in the global market, and promoting them as ‘less harmful’ products⁶.

In January 2020, the sale of IQOS (HTP brand marketed by PMI) and Eclipse (marketed by RJ Reynolds) was authorized in the United States⁷. The US Food and Drug Administration (FDA) first authorized HTPs in April 2019, and in July 2020 designated the leading HTP brand, IQOS, as a modified risk tobacco product (i.e. authorized under an exposure modification order), enabling its marketing as a reduced exposure product, aligned with the company’s claims of harm reduction⁸. However, the concept of ‘reduced exposure’ (e.g. only suggesting a product contains reduced levels of certain chemicals) may be easily misconstrued by consumers, particularly by youth and young adults, as ‘reduced harm’. This perception of ‘reduced harm’ suggests that such products significantly reduce the risk of tobacco-related diseases^9,10. This issue may be of particular concern with new tobacco products since it could affect the susceptibility of youth and young adults to these products¹⁰.

Although the health consequences of HTP use remain uncertain¹¹, there is growing public health concern about potential adolescent initiation and use of HTPs¹². Previous studies identified several correlates of HTP use among US adolescents including current tobacco use (e.g. cigarettes, e-cigarettes), being Hispanic, and familial use of HTPs^13,14; however, there is still a knowledge gap regarding other potential risk factors of HTP use among US adolescents. For example, the briefing document from PMI indicated that IQOS may attract those who favor menthol cigarettes¹⁵. Also, multiple tobacco product use has been associated with HTP use among Korean adolescents^16,17. Nonetheless, these associations are yet to be examined among adolescents in the US. Therefore, this study aimed to examine the association between the use of multiple tobacco products and flavored tobacco products with HTP use among a US nationally representative sample of adolescents.

METHODS

RESULTS

Table 1 shows the sample characteristics and prevalence of HTP awareness and use, by associated factors. Among all respondents (n=19018), 12.8% reported awareness of HTPs (unweighted n=2390), 2.3% (n=398) reported ever use, and 1.6% (n=291) reported current use of HTPs. In terms of the current tobacco use status (not including HTPs), of all respondents, 14.8% (n=2685) reported single tobacco product use and 7.7% (n=1357) reported currently using two or more tobacco products. Furthermore, 16.0% (n=2954) reported past 30 days use of any flavored tobacco products (e.g. cigars, e-cigarettes) and 1.7% (n=292) reported past 30 days use of menthol cigarettes.

Dual/poly tobacco product users, compared to non-users and single tobacco product users, reported the highest rates of awareness of HTPs (18.0%, weighted; vs 12.3% of non-users and 11.5% of single tobacco product users), ever use (11.0% vs 1.0% of non-users and 3.6% of single product users), and current use (10.5% vs 0.3% of non-users and 2.7% of single product users). Usual menthol cigarette users (vs none users) reported higher awareness (29.1% vs 12.5%), ever use (23.1% vs 2.0%), and current use of HTPs (19.7% vs 1.3%). Past 30 days flavored tobacco users (vs none users) also reported higher level of awareness (15.7% vs 12.2%), ever use (7.9% vs 1.3%) and current use of HTPs (6.7% vs 0.6%).

Table 2 shows the likelihood of awareness and use of HTPs by several associated factors. Higher odds of awareness of HTPs were associated with familial use of HTPs (AOR=4.78; 95% CI: 3.20–7.13), usual menthol cigarette use (AOR=1.77; 95% CI: 1.23–2.53), and past 30 days flavored tobacco use (AOR=1.44; 95% CI: 1.16–1.80). Risk factors for ever HTP use included single tobacco use (AOR=2.52; 95% CI: 1.19–5.33) and dual/poly tobacco use (AOR=4.94; 95% CI: 2.56–9.54), being male (AOR=1.81; 95% CI: 1.06–3.10), familial use of HTPs (AOR=9.78; 95% CI: 5.65–16.94), usual menthol cigarette use (AOR=2.50; 95% CI: 1.66–3.76), and past 30 days flavored tobacco use (AOR=1.61; 95% CI: 1.07–2.44). Risk factors for current HTP use included single (AOR=10.84; 95% CI: 6.72–17.49) and dual/poly tobacco use (vs none) (AOR=31.96; 95% CI: 17.79–57.43), being Hispanic (AOR=1.62; 95% CI: 1.10–2.37), familial use of HTPs (AOR=6.07; 95% CI: 3.66–10.07), and usual menthol cigarette use (AOR=2.50; 95% CI: 1.63–3.85).

DISCUSSION

We believe this is the first national study in the US to examine the association between knowledge and use of HTPs and other tobacco use status (mono/dual/poly tobacco use), as well as other flavored tobacco use (menthol cigarettes and flavored e-cigarettes), consistent with previous findings^12,13,15. This study documents HTP use in adolescents and adds insight and urgency into prioritizing targeted interventions for adolescents who are current users of other tobacco products, flavored tobacco product users, Hispanic adolescents, and those whose family members use HTPs. Of particular concern for children is the association between HTP use and poly-tobacco use, which echoes previous findings among Korean adolescents^16,17. The underlying mechanisms of polytobacco use among adolescents may be explained by several frameworks such as the neurobiological framework¹⁹ and the social/contextual/situational frameworks^20,21. Accordingly, it is important to understand the unique context of HTP use (i.e. why, when, where, with whom it is used, and perceptions/attitudes toward HTPs) and to incorporate contextual factors in the development of prevention strategies for youth tobacco use such as educational campaigns¹³.

Another potential concern related to HTP use is flavors. The underlying mechanism related to the co-use of flavored tobacco products and HTPs is still unclear, yet it is expected that flavors in HTP may attract flavored tobacco users. For example, the International Tobacco Control Policy Evaluation Project–Japan survey found adult HTP users who were currently smoking cigarettes preferred menthol-flavored HTPs²². We also found that among current HTP users, 21.2% reported that they used flavored HTPs in the past 30 days (results not shown). In the current US market, only menthol-flavored HTPs are available¹, but tobacco companies may be considering options for introducing other flavors in the future as they have done with other tobacco products¹. Even though the proportion of flavor use remains lower for HTPs compared with other tobacco products (e.g. e-cigarettes), it is important to continuously monitor the flavored product use in HTPs²³ and potential future marketing strategies (e.g. introducing new flavors) as flavors are the primary reason why youth are attracted to tobacco products¹⁵.

Of note, we found specific risk factors associated with the experimentation and current use of HTPs. For example, being male was associated with experimentation, but not current use of e-cigarettes. In general, boys are more likely than girls to use tobacco products²⁴, and a PMI briefing document revealed that adult males were more likely to be attracted to HTPs than females¹⁵. Also, those who currently used any flavored tobacco products (except for menthol cigarettes) were more likely to experiment with HTPs but did not continue to use them. Adolescents who are using flavored tobacco products may have a higher tendency to experiment with new tobacco products in general²⁵. Further, even though the likelihood of experimentation was not significantly different for Hispanics compared with non-Hispanic White youth, Hispanics were more likely to currently use HTPs. A previous report suggested that Hispanic adults were more attracted to HTPs¹⁵, possibly due to social norms or acculturation²⁶. However, due to the paucity of studies on HTPs, the underlying mechanisms explaining these factors, particularly as they relate to experimentation and escalation of HTP use, are still unclear. More research is needed to examine the neurobiological and psychosocial underlying mechanisms that explain these behavioral patterns.

CONCLUSIONS

Healthcare professionals and educators should screen and warn adolescents and their families about all forms of tobacco use, including HTPs²⁷. Tobacco regulatory policies on HTPs are likewise critical^6,8. Even if the rates are arguably low as of 2019, as the availability of HTPs and marketing practices (e.g. advertisements) increases, the awareness and use among adolescents is expected to increase in the future. For example, a study from Japan reported HTP use increased from 0.2% in 2015 to 11.3% in 2019, likely due to the increased availability of HTPs over this time period²⁸. Thus, it is important to monitor changes in HTP availability as well as individuals’ awareness and use of HTPs over time. As with other emerging nicotine products like e-cigarettes, adolescents may be drawn to HTPs due to industry marketing strategies that add attractive flavors and support sleek designs^1,23. Therefore, it is important to proactively develop and enforce regulatory policies that include product packaging and advertising restrictions, minimum age requirements, and tobacco retailer licensing and zoning⁸. The recent FDA authorization of IQOS (one of the HTP brands) as Modified Risk Tobacco Products (MRTPs) mandates the urgent need for continuous surveillance and prevention in partnership with families, schools, clinicians, and policymakers.