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

SUMMARY Background The perceived reduced formation of harmful chemicals (RF) or perceived reduced risk of harm (RH) of a smoke-free tobacco product relative to combustible tobacco products may influence its acceptance and use patterns among adult smokers and therefore impact public health. We analyzed whether and how the RF and/or RH of the heated tobacco product (HTP) IQOS™ impacted “exclusive” (100%) IQOS™ use in Japan, Italy, Germany, and Russia. Methods Between 2016 and 2020, adult participants from longitudinal IQOS™ user cohorts in Japan (N = 6257), Italy (N = 8137), Germany (N = 8474), and Russia (N = 7231) repeatedly indicated the reasons for using IQOS™, including reasons referring to RF and RH, during their first 48 weeks in the cohort. Logistic and Cox regression were used to analyze the relationships between RF and/or RH indications for using IQOS™ and exclusive or stable exclusive IQOS™ use. Results At week 48, exclusive IQOS™ use in Japan (odds ratio [OR] = 1.89), Italy (OR = 3.35), Germany (OR = 3.48), and Russia (OR = 3.05) was more likely among participants who more frequently (highest vs. lowest category of number of RF and/or RH indications) indicated RF and/or RH as a reason for using IQOS™. In Japan, where other HTPs were also marketed, this was also true for the overall HTP category. Also, in Japan where RF and RH could be indicated separately as reasons for using IQOS™, indicating RH (OR = 2.92) compared to RF (OR = 1.81) resulted in a greater likelihood of exclusive IQOS™ use within the highest category of RF or RH indications. In Japan (hazard ratio [HR] = 0.74), Italy (HR = 0.80), Germany (HR = 0.72), and Russia (HR = 0.85), IQOS™ users who indicated RF and/or RH as a reason for using IQOS™ had a lower risk of becoming a stable nonexclusive than stable exclusive IQOS™ user as well as a 10–25% lower number of weeks until reaching stable exclusive IQOS™ use. Conclusions Perceived reduced formation of harmful chemicals (RF) or perceived reduced risk of harm (RH) of IQOS™ have a significant impact on IQOS™ users’ switching to exclusive IQOS™ use and the acceleration of stable exclusive IQOS™ use. This may also be true for the overall HTP category. Moreover, perceived RH of IQOS™ seems to be a stronger driver for exclusive IQOS™ use than perceived RF. [Contrib. Tob. Nicotine Res. 32 (2023) 50–64]