Heated tobacco product use and combustible cigarette smoking relapse/initiation among former/never smokers in Japan: the JASTIS 2019 study with 1-year follow-up.

BACKGROUND: Use of heated tobacco products (HTPs), which were first launched in Japan, has been rapidly spreading worldwide. The present study aimed to investigate whether HTP use was associated with combustible cigarette smoking relapse/initiation among former/never combustible cigarette smokers.
METHODS: A prospective cohort study was conducted by analysing two waves of data from the Japan 'Society and New Tobacco' Internet Survey. Among the 7766 never/former combustible cigarette smokers who answered the baseline survey in 2019, 5947 (follow-up rate: 76.6%) responded to the follow-up survey in 2020 (age range 18-73 years old; 50.5% men). The association between HTP use and combustible smoking after 1 year was investigated by multivariable logistic regression analysis adjusting for potential confounders.
RESULTS: Of the respondents, 308 (5.2%) used HTPs at baseline. One year later, 97 (1.7%) non-HTP users and 39 (12.7%) HTP users were smoking combustible cigarettes. Among former smokers who had quit for 1 year or more and among never smokers, HTP use was significantly associated with combustible cigarette smoking 1 year later (OR=2.80, 95% CI 1.42 to 5.52 and OR=9.95, 95% CI 3.39 to 29.16, respectively), while the association was not significant among former smokers who recently quit.
CONCLUSION: HTP use was associated with relapse/initiation of combustible cigarette smoking after 1 year. The risks of HTP use, including subsequent combustible smoking, should be carefully monitored. © Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.