How do Risk Perceptions Drive Smokers to Completely Switch to a Smoke-Free Tobacco Product (IQOS^™)? A Four-Country Cohort Study

Substitution of combustible tobacco products (TP) with less harmful smoke-free (i.e., non-combustible) TP alternatives is an important public health strategy of tobacco harm reduction, with complete (i.e., 100%) substitution being more effective in reducing individual and population harm than only partial substitution (1–4). To achieve this, smoke-free TPs must be accepted and adopted by adult smokers who otherwise would continue to smoke so they can completely switch from combustible to smoke-free TPs (2–3). It is therefore important to identify the major sociodemographic (5–6) and motivational factors that drive acceptance of and complete switching to smoke-free TPs, in order to inform research and tobacco control policies on strategies to increase the number of smokers who completely switch to smoke-free TPs, which will reduce overall population harm (7–8). The motivations and reasons why adult smokers switch – or do not – from combustible to less harmful smoke-free TPs differ (5–6, 9–10) and may vary from country to country (10–11). Motivations to switch to smoke-free TPs include similarity with combustible TPs (9, 12); sensory properties and nicotine delivery (7, 12–13); satisfaction (7, 9); enjoyment (9, 14), convenience (7); appraisal of new technologies (9); absence of smoke, reduced smell, and cleanliness (9, 15); social acceptability (9, 14); and intentions to reduce or quit smoking altogether (6–7, 9, 12–13, 15–16); but also prevailing health conditions (6), and notably the perceived risk of harm of TPs (7, 9, 14, 17–22). Indeed, accurate, truthful and non-misleading scientific communication on the reduced risk profile of smoke-free TPs, such as the reduced exposure and reduced risk claims authorized by the United States Food and Drug Administration (US FDA) in the modified risk TP (MRTP) order (23–27), may facilitate adult smokers’ switching from combustible to smoke-free TPs (1, 7, 9, 28).

To date, however, there is limited information on whether and how the perceived risk of harm of a smoke-free TP impacts switching to smoke-free TP use (17–18, 29–30). One study investigated the impact of perceived harm on complete switching to “exclusive” (i.e., 100%) use of a smoke-free TP (18). The authors found that among adult dual users of cigarettes and e-cigarettes who participated in the U.S. Population Assessment of Tobacco and Health (PATH) study, those who perceived e-cigarettes as less harmful than cigarettes appeared more likely to switch to exclusive e-cigarette use (18). However, to our knowledge no other study has investigated the impact of perceived risk of harm on future use of heated tobacco products (HTP), and in particular, on exclusive use of HTPs.

HTPs, including the HTP IQOS^™, are a category of smoke-free TPs that heat tobacco but do not burn it and therefore have the potential to present considerably less risk of harm than combustible TPs (12). As a consequence, smokers who completely switch to IQOS^™ or other scientifically substantiated HTPs are exposed to much lower levels of harmful chemicals than those who continue smoking cigarettes (23, 31–34). Moreover, HTPs contain tobacco and therefore provide smokers a similar experience (e.g., sensory properties, nicotine delivery profile, and ritual) to that of smoking a cigarette (12–13), thus positioning HTPs as acceptable alternatives to cigarettes.

In the present prospective longitudinal study, we investigated whether and how the perceived reduced formation of harmful chemicals (RF) or the perceived reduced risk of harm (RH) of the HTP IQOS^™ impacted IQOS^™ use patterns – in particular “exclusive” IQOS^™ use and “stable exclusive” IQOS^™ use – among IQOS^™ user consumer cohorts in the four culturally and socioeconomically different countries Japan, Italy, Germany, and Russia.

The present study is the first to cross-culturally and longitudinally investigate whether and how the perceived reduced formation of harmful chemicals (RF) or perceived reduced risk of harm (RH) of a smoke-free HTP impacts its exclusive and stable exclusive use. In four culturally and socioeconomically different countries, IQOS^™ users who indicated RF and/or RH as a reason for using IQOS^™ during follow-up were more likely to (i) be exclusive IQOS^™ users after about 1 year of follow-up, (ii) become stable exclusive IQOS^™ users during follow-up, and (iii) become stable exclusive IQOS^™ users more rapidly than those who did not indicate RF and/or RH as a reason for using IQOS^™. Moreover, the data from Japan suggest that IQOS^™ users who consistently perceived IQOS^™ as an RH product over time, were more likely to become exclusive IQOS^™ users than those who consistently perceived IQOS^™ as an RF product. Finally, the Japanese data suggest that the relationships identified for IQOS^™ are also true for the overall HTP category.

Despite the cultural and socioeconomic diversity of the countries where IQOS^™ user samples for the present study were drawn, all four samples were similar regarding the mean age and age range. Also, in all countries most participants were male, had completed high school/university, and had active employment status, allowing for comparability of the study results across the countries. Moreover, the sex and age profiles of the randomly selected samples of IQOS^™ users in the four countries are comparable to HTP users of nationally representative surveys. Taking Japan as an example, the sex and age profile of IQOS^™ users in the present study (76% men and 61% in the 21–49 year age group) is similar to the sex and age profile of HTP users from the Japanese Ministry of Health 2019 National Health and Nutrition Survey (36) (77% male and 60% in the 20–49 year age group).

Using a sequential three-step analysis approach (A-1 to A-3), we calculated effect sizes for different aspects of RF and/or RH and exclusive IQOS^™ use. Given the different nature of the three analyses, for all four countries the effect sizes of A-1 (OR: 1.39–2.29) were intermediate between those of A-2 (OR: 1.89–3.48) and A-3 (HR: 0.74–0.82, i.e., 1.2 to 1.4 times impact). The higher effect sizes of A-2, which show the impact that RF and/or RH may have on exclusive IQOS^™ use, result from the comparison of the extreme (lowest versus highest) categories of the number of RF and/or RH indications during follow-up. Conversely, we observed lower effect sizes of the most advanced and stringent A-3, which also considered the time period the individual IQOS^™ users were stable exclusive users. This is because in this analysis, IQOS^™ users had not only to fulfill the criterion of being an exclusive IQOS^™ user, but also the criterion of being a stable exclusive IQOS^™ user. In Japan, where other HTPs (e.g., Glo^™ and Ploom^™) are also marketed, A-2 revealed that repeatedly indicating (having certainty about) RF and/or RH as a reason for using IQOS^™ was very strongly (OR = 4.87) associated with an increase in the likelihood of exclusive HTP use by a factor of 4.9. This is much higher than the corresponding likelihood for exclusive IQOS^™ use only (OR = 1.89) in Japan and may be explained by two factors acting together: (i) the inherent likelihood of exclusive IQOS^™ use (i.e., use of IQOS^™ brand only; all combined use of IQOS^™ with other HTP brands and/or cigarettes, cigarette use only, or other TP use would result in non-exclusive IQOS^™ use) was lower than that of exclusive HTP use (i.e., any HTP brand or HTP brand combination possible; only combined use with cigarettes, cigarette use only, or other TP use would result in non-exclusive HTP use); and (ii) HTP users of more than one HTP brand may have more certainty about the RF/RH of HTPs and therefore are more likely to indicate RF and/or RH as reason for using IQOS^™/HTPs during follow-up more frequently. This suggests that across the entire HTP category, there is a very high potential for HTP users to completely switch from combustible TPs to exclusive HTP use, providing that they are certain about the RF or RH profile of HTPs. Moreover, in Japan, where IQOS^™ users were able to indicate RF or RH individually as reasons for using IQOS^™, A-2 revealed that consistently indicating (having certainty about) RH (OR = 2.92) had the potential to switch combustible TP users 1.6 times more effectively to exclusive IQOS^™ use than consistently indicating (having certainty about) RF (OR = 1.81). These results illustrate how the degree of certainty of perceived harm reduction can influence TP use (37). They also reinforce the need for clear, credible, and balanced information (8, 17); education and knowledge (11, 38); and communication (11) on the RF and RH profiles of different TP categories as well as correction of misperceptions (8, 11, 30). Armed with accurate information, TP consumers can understand and have certainty about the relative risks of the various TPs and can make informed choices regarding their use (11). This is of particular importance because misperceptions such as that HTPs or e-cigarettes are equally or even more harmful than cigarettes are still widely prevalent (8, 30). Understanding public perceptions of TP harm is important to help regulators develop appropriate policies and regulations for TP use (30). Eventually, public understanding has to be aligned with the general conclusions of authoritative sources, i.e., that smoke-free TPs are generally less harmful than combustible TPs (29, 38). Moreover, public health messages should help consumers understand how their individual health risk would change if a smoke-free TP is used only partially or exclusively (39). Finally, in the present study, the results of A-3 revealed that perception of IQOS^™’ RF and/or RH increased the likelihood of stable exclusive IQOS^™ use by up to 1.4-fold and shortened the time to reach stable exclusive IQOS^™ use by up to 25%. This underlines the importance of RF and RH communication in facilitating and accelerating of complete switching to stable exclusive IQOS^™ use, and probably also to overall stable HTP or other smoke-free TP use. Indeed, to achieve overall population harm reduction, switching to stable exclusive smoke-free TP use is the most important behavioral change among smokers who do not quit all TP use.

To our knowledge, only one other study investigated the impact of perceived reduced harm on subsequent exclusive smoke-free TP use. In this study, Persoskie et al. (18) examined data from US adult dual users of cigarettes and e-cigarettes (n = 2211) collected from the nationally representative longitudinal PATH study. The 1-year followup (2014–2015) of this study revealed similar results for perceived harm and subsequent e-cigarette use as those observed in the present study for IQOS^™ or HTP use. The authors reported that dual users of cigarettes and e-cigarettes who perceived e-cigarettes as less harmful than cigarettes were more likely to become exclusive e-cigarette users 1 year later (OR = 2.9 [95% CI: 1.7–4.8]) (18). This OR of 2.9 is not directly comparable with the OR revealed in the present study because we measured perceived reduced e-cigarette harm as a yes/no predictor variable, whereas the logistic regression model used by Persoskie et al. (18) compared a “less harmful” category versus a collapsed group of three categories consisting of “about the same”, “more harmful”, and “don’t know”. However, the OR of 2.9 is intermediate between the lower ORs (1.39–2.29) revealed in the present study in A-1 and the higher ORs (1.89–3.48) revealed in the present study in A-2, suggesting that the association between harm perception and subsequent exclusive use of e-cigarettes is similar to that of IQOS^™ and the overall HTP category.

Two further studies (17, 29) also investigated the impact of perceptions of harm on future e-cigarette use. However, neither study differentiated between switching partially or completely to e-cigarette use. Similar to the study by Persoskie et al. (18), an earlier UK study by Brose et al. (17) longitudinally assessed a general population sample of British adult smokers and former smokers (n = 6165) with a 1-year follow-up (2012–2013) and reported that among those who had never used e-cigarettes, perceiving e-cigarettes as less harmful than cigarettes predicted subsequent e-cigarette use (OR = 1.39 [95% CI: 1.08–1.80]). Unlike Persoskie et al. (18), this UK study did not assess switching from dual (e-cigarette and cigarette) to exclusive e-cigarette use, but switching from never e-cigarette to e-cigarette use. This might explain the lower OR of 1.39 compared to the OR of 2.9 reported by Persoskie et al. (18), assuming that switching from never e-cigarette use to e-cigarette use is less likely than from dual e-cigarette use to exclusive e-cigarette use. Similarly, another study by Elton-Marshall et al. (29) based on longitudinal data (26,446 US adults) from the PATH study with a 1-year follow-up (2014–2015) reported that among non-current (93.4%) and current (6.6%) users of e-cigarettes, perceiving e-cigarettes as less harmful than cigarettes predicted subsequent e-cigarette use (OR = 1.97 [95% CI: 1.74–2.22]). As with the study of Brose et al. (OR = 1.39) (17), the lower effect size (OR = 1.97) compared to that of Persoskie et al. (OR = 2.9) (18) might be because Elton-Marshall et al. also did not assess switching from dual to exclusive e-cigarette use, but from primarily non-current to subsequent e-cigarette use.

Communication about the RF and RH profile of smoke-free TPs – particularly claims authorized by recognized health authorities such as the US FDA’s MRTP order and related claims (23, 25–27) – have been shown to motivate smokers to switch from combustible to smoke-free TPs (1, 7, 9, 28). In the present study, the reasons (“claims”) the participants could indicate why they were using IQOS^™ (Table 1) were relative RF and RH messages, i.e., the RF or RH of using IQOS^™ in comparison to smoking cigarettes. As opposed to absolute harm messages, relative messages have been shown to be more effective in reducing harm perceptions and increasing use intentions of smoke-free TPs among smokers (8). Similarly, relative harm perceptions seem to be more important to individuals’ TP information-seeking behaviors (39) and are associated with smoking onset and cessation (37) as well as switching to smoke-free TPs (17–18, 29). This suggests that people consider the health risk of TP use in terms of relative harm (37), so that tobacco control policy, regulation, and the content of public health messages should be informed by relative harm perceptions (39). Depending on the country, in the present study the reasons that could be indicated for using IQOS^™ included either both RF and RH reasons, or an RF or RH reason alone. Of those, the reasons related to RF were similar to the second claim (see authorized statement II below) of the authorized Reduced Exposure information that PMI was granted for IQOS^™ as part of its MRTP marketing order by the US FDA in July 2020 (23). The authorized information includes the available evidence to date: “(I) The IQOS^™ system heats tobacco but does not burn it; (II) this significantly reduces the production of harmful and potentially harmful chemicals; and (III) scientific studies have shown that switching completely from conventional cigarettes to the IQOS^™ system significantly reduces your body’s exposure to harmful or potentially harmful chemicals.” Therefore, given the similarity of RF reasons used in the present study with the Reduced Exposure claim (II) authorized for IQOS^™ by the US FDA and the consistent effect sizes and results revealed in the present study for the four countries with different cultural and socioeconomic background, it is likely that the impact of the authorized Reduced Exposure claim (II) on the IQOS^™ use patterns in the US (or other countries where comparable RF claims have been or will be communicated) will be similar to those identified in the present study. Also, if RH claims for IQOS^™ or other HTPs that are similar to the RH reasons used in the present study were communicated in the U.S. or any other country, the use patterns of IQOS^™ or other HTPs could be expected to be similar to those observed for IQOS^™ and HTPs in the present study.

The perceived reduced formation of harmful chemicals (RF) or perceived reduced risk of harm (RH) of IQOS^™, especially when indicated with certainty, has a significant and meaningful impact on complete switching to exclusive IQOS^™ use and the facilitation and acceleration of stable exclusive IQOS^™ use. This also appears true for the overall HTP category. Moreover, RH of IQOS^™ seems to be a stronger driver for complete switching to exclusive IQOS^™ use than RF. Our findings suggest that perceptions of the harm of HTPs and possibly also of other smoke-free TPs play an important role in tobacco harm reduction because they facilitate and accelerate adult smokers’ complete and permanent switching to less harmful smoke-free TPs.

With regard to public health, it is important to continuously monitor exclusive and stable exclusive smoke-free TP use in post-market settings and ensure that adult smokers have access to accurate relative risk information to facilitate their switching from combustible to smoke-free TPs. Continuous post-market monitoring can also help clarify the risk perceptions of TPs in both smoke-free TP users and the population as a whole.