To our knowledge, this study is the first to describe characteristics of individuals who used IQOS® and comprehensively assess use behaviors and risk perceptions relevant to IQOS® use in a real-world setting among established AUI in the US. To summarize, our results showed that the vast majority of established AUI were existing smokers with an average of greater than 20 years of smoking history; more than 80% had either never used or had tried but stopped using tobacco cessation treatment. After an average of 1.2 years of IQOS® use, almost half of AUI were not smoking at the time of the assessment, and > 80% of participants who were still smoking indicated they had reduced their cigarette consumption. Over 80% of participants perceived IQOS® use as less harmful compared to cigarette smoking; few perceived IQOS® use as risk free.
These findings provide first-hand empirical evidence in a real-world setting to support the harm reduction potential of IQOS® in facilitating individuals who smoked cigarettes, especially among those who did not use cessation treatment or did not successfully quit smoking after trying cessation treatment, to switch to IQOS®. Our results extend findings from previous studies in other countries by documenting that the vast majority of individuals who used IQOS® smoked cigarettes when they first tried IQOS®, and few had never smoked a cigarette [21, 22]. These individuals had a relatively long smoking history (i.e., > 20 years on average). After an average of 1 year of IQOS® use, almost half of participants were not smoking combusted cigarettes anymore. Although not directly comparable, the portion of participants who became noncurrent smokers was one of the largest among smoke-free products (e.g., e-vapor products) to the best of our knowledge [23–26].
Previous studies have found that young adults were more likely to use e-vapor products compared to older adults [27, 28]. In contrast, we found those who used IQOS® tended to be middle-aged or older adults and with a relatively long smoking history. In addition, the majority of participants had never tried a cessation treatment and another 31% tried but discontinued cessation treatment. Therefore, IQOS® may be particularly beneficial to those who are older, have a long history of smoking, and did not use or were not successful using tobacco cessation treatment. Along with the finding of minimal uptake among individuals who had never smoked cigarettes, our results indicate that IQOS® is appropriate for the protection of public health.
With respect to IQOS® use, the majority of participants used IQOS® daily and used greater than 15 HeatSticks® per day on days used. This level of IQOS® consumption was generally in line with cigarette consumption among smokers in national surveys [29–31], and daily use of IQOS® has been associated with IQOS® use exclusive of cigarette smoking (vs. dual use of IQOS® and combusted cigarettes) [32, 33]. Taken together, these results suggest replacement of cigarettes with IQOS® use.
Correct perception of IQOS® risk can play an integral role in switching behaviors. In line with the large body of literature showing that individuals who perceive smoke-free tobacco products as less harmful compared to cigarettes were more likely to switched to such products from cigarette smoking [34, 35], a previous study has documented that individuals who used IQOS® exclusively (of smoking) were more likely to perceive IQOS® as less harmful than cigarettes as compared to those who used IQOS® and smoked cigarettes (i.e., dual use) [32]. Given this context, it is encouraging to observe that over 80% of participants of this study correctly identified the reduced exposure to harmful or potentially harmful chemicals when switching completely from cigarettes to IQOS®, and few participants incorrectly identified “no exposure.”
With respect to HeatStick® varieties, we found an interesting pattern that suggests that menthol HeatSticks® were used and preferred by not only individuals who preferred menthol cigarettes, but also a sizable portion of those who preferred non-menthol cigarettes. That is, although Amber (or Original) was the most commonly ever (71%) and first (53%) tried variety, the two menthol varieties accounted for the majority of varieties used most often at the time of assessment. This is aligned with the observation that approximately 1 in 5 individuals who preferred non-menthol cigarettes preferred menthol HeatSticks®; in contrast, only 1 in 20 individuals who preferred menthol cigarettes preferred Amber (or Original) HeatSticks®. Although it is not clear why menthol HeatSticks® were more commonly preferred than Amber HeatSticks®, such findings support the potential role of menthol HeatStick® varieties in continued IQOS® use.
In this study, we found that ever and current use of other tobacco products was more common among participants of this study (with e-vapor products being the most common) compared to that among smokers based on estimates from national surveys [36]. This may signal those individuals open to trying and using other tobacco products were more likely to try and use IQOS®. When compared to the time before trying IQOS®, we observed a ~ 30% reduction in e-cigarette use. It is possible that some participants were using e-vapor products to help stop cigarette smoking but were not successful; after start using IQOS®, they stopped using e-vapor products. Future studies that assess reasons to stop using other tobacco products will shed new light on this topic.
Our findings should be interpreted with the following limitations in mind. First, the study is based on self-reported information. Although we are not aware of any validation studies on self-reported IQOS® use behaviors, the larger literature supports a reasonable validity of self-reported behaviors in tobacco research [37]. In addition, many measures relied on recalled information (e.g., behaviors during the 30 days before first trying IQOS®), for which recall bias cannot be ruled out. We tried to minimize recall bias by (i) asking about prominent behaviors generally easy to recall, such as whether they smoked cigarettes during the 30 days before first trying IQOS®, and (ii) limit the length of the recall period as short as possible (e.g., past 30 days). Second, it is estimated that approximately 70% of individuals who purchased IQOS® registered in the database. Moreover, of all individuals invited to complete the eligibility assessment, only 10.5% did so. It is unknown whether individuals who registered in the database or responded to the invitation are representative of all AUI in the United States. Also, due to limited distribution of IQOS®, it is not clear whether these results would apply to all adults who smoke in the US. Nonetheless, we provided the first estimates of perceptions and behaviors related to IQOS® use from a sample large enough to produce meaningful results. Third, the study was conducted among AUI, so we cannot provide information about the prevalence of IQOS® use in the general US population. Finally, no definitive evidence can be drawn for causal relationships from this observational study. It is noteworthy that during the recruitment period, a notification was sent to IQOS® consumers on October 13, 2021 informing them that IQOS® would become unavailable after November 28, 2021. In consideration of the potential impact of this communication on consumer behaviors, we also conducted analyses only using data collected before that date (n = 463). Results from this subsample are generally in line with the results for the full sample.