Social norms and subsequent product use among people who use cigarettes and heated tobacco products in Japan

Aims:  To examine the differences in social norms towards heated tobacco products (HTPs) and cigarettes across those who use HTPs or cigarettes exclusively or both products concurrently and to quantify the longitudinal association between social norms on cigarettes and HTPs and subsequent tobacco product use.

Methods: Data were collected from people who used tobacco products and participated in at least two consecutive waves of ITC Japan study conducted between 2018 (Wave 1) and 2021 (Wave 4). Socio-economic characteristics, patterns of tobacco products use, harm perception towards HTP and social norms towards cigarettes and HTPs uses were compared between those who use HTPs or cigarettes exclusively or use both products concurrently. Association between social norms at baseline wave and tobacco product use in the follow-up wave were assessed using generalized estimating equations on weighted data, controlling for demographics.

Results: While most perceive HTP use as less harmful than cigarettes, 29.6% of those who use cigarette exclusively lack awareness of HTP harm. Across groups (exclusive cigarette, exclusive HTP, dual product uses), many have smoking friends (84.7%, 83.3%, 85.3%) and perceive disapproval of smoking from close circles (49.3%, 52.5%, 57.2%) and society (67.2%, 67%, 65.5%). Those who use HTP exclusively more often have friends using HTPs (78.16%) and perceive disapproval of HTP use from friends (39.1%) and society (38.9%). While most continue product use in the follow-up wave, those who use HTP exclusively were more likely transition to non-current users. Perceived positive social norms towards cigarette use were significantly associated with continued exclusive cigarette use in the next wave. Having friends using HTPs increased the likelihood of using HTP in the next wave, either exclusively or concurrently with cigarettes, or reducing tobacco product use to non-current level, relative to exclusive cigarette use. However, perceiving that the public was approved of or being neutral towards HTP use was also associated with increased likelihood of continued cigarette use in the next wave, mostly concurrently with HTP.

Conclusions: To address these dynamics, public health interventions should focus on clear communication, targeted education, and promoting healthier social norms, while simultaneously dispelling misconceptions about HTP harm and creating supportive environments for smoking cessation.