Objective:
In Japan, the use of heated tobacco products (HTPs) has increased substantially between 2016 and 2017. Previous reports on the early phase of the HTP epidemic showed men, younger people, and current cigarette smokers with intention to quit are more likely to start using HTPs than women, older people, never smoker, and former smokers. The aim of this study is to clarify how HTP use (IQOS, Ploom TECH, and glo) spread across the different cigarette smoking status and intention to quit categories, by time series analyses pre- and post-2016 HTP epidemic in Japan.

Methods:
Two sets of pre- and post-2016 data from the Japan “Society and New Tobacco” Internet Survey (JASTIS) were analyzed: N=5,403 (2015-16) and N=3,468 (2017-18). Multivariable logistic regression models for current HTP use in the last 30 days by baseline characteristics such as smoking status (never smoker, former smoker, current smoker with intention to quit, and current smoker without intention to quit) were used adjusting for socio-demographic factors.

Results:
HTP use increased by about 11 times post-2016 epidemic compared with pre-2016 epidemic according to the adjusted odds ratio (95% CI) for HTP use of 11.0 (7.54-16.0). According to smoking status, significantly higher adjusted ORs (95% CIs) of current HTP use for the post-2016 were observed: 3.33 (1.79-6.18) for never smokers, 8.81 (4.20-18.4) for former smokers, 28.0 (6.78-116) for current smokers with intention to quit, and 16.4 (9.11-29.6) for current smokers without intention to quit.

Conclusions:
After the 2016 HTP epidemic, prevalence of current HTP use dramatically increased in all subgroups except for never smokers; not only among current cigarette smokers but also former smokers. HTPs might therefore be a gateway to the continue use and also relapse of tobacco products.