Evaluating trends in cigarette and HTP use in Japan and measurement issues in the National Health and Nutrition Survey.

Introdution: Studies have reported that the rapid rise in heated tobacco product (HTP) sales in Japan accompanied an accelerated decline in cigarette sales. However, these studies do not distinguish whether those who previously smoked cigarettes became dual users with HTPs (smoking fewer cigarettes) or instead switched completely to HTPs. If HTPs present lower health risks than cigarettes, replacing cigarettes with HTPs is more likely to improve public health than cigarette users continuing as dual users.

Methods: To evaluate the role of HTP introduction relative to smoking prevalence, we examine trends in cigarette prevalence as related to trends in HTP use using Japan's National Health and Nutrition Survey (NHNS) from 2011 to 2019. We develop measures of relative changes in smoking prevalence use by age and gender in the pre-HTP and post-HTP periods. We then analyse prevalence data by year using joinpoint regression to statistically distinguish changes in trend.

Results: Compared with the pre-HTP 2011-2014 period, cigarette prevalence decreased more rapidly during the post-HTP 2014-2017 period, particularly among younger age groups. However, the changing format of NHNS questions limits our ability to determine the impact on smoking prevalence, particularly after 2017.

Conclusions: While suggesting that HTPs helped some people who smoke to quit smoking, this study also shows the difficulties in eliciting accurate survey responses about product use and distinguishing the impact of a potentially harm-reducing product in an environment subject to rapidly evolving patterns of use.