Patterns of use of heated tobacco products: a comprehensive systematic review

Introduction: Relative or absolute safety of heated tobacco products (HTP) remains unknown, while independent literature suggests that these products do not favour tobacco control. We conducted a comprehensive systematic review and meta-analysis to evaluate HTP usage patterns and the effect of HTP use on conventional tobacco smoking (use transitions). Methods: We used Pubmed/MEDLINE, Embase and the Cochrane Library to identify all articles published up to February 2022 on HTP use. For the present review, we included all representative cross-sectional studies dealing with HTP use, and all prospective cohort studies or cross-sectional studies on conventional tobacco smoking transitions due to HTP use. From 610 non-duplicate articles, 76 were eligible (71 cross-sectional and 5 prospective cohort studies). Results: Compared with young adults, HTP use was less frequent among middle-aged (pooled odds ratio, OR=0.59; 95% confidence interval, CI: 0.48-0.74; number of studies, n=15) and older adults (OR=0.17; 95%-CI: 0.07-0.38; n=12). HTP use was more frequent among former (OR=2.73; 95%CI: 1.03-7.25; n=6) and current smokers (OR=14.53; 95%-CI: 6.34-33.31; n=12). Overall, 68.3% of HTP users were dual users (n=26). Eight studies (including 5 cohorts) showed that HTP users were more likely than non-users to start conventional cigarette smoking (OR=6.31; 95%-CI: 4.13-9.65; n=2), whereas current cigarette smokers using HTPs were less likely to quit (OR=0.84; 95%-CI: 0.80-0.89; n=4). Conclusions: We found that HTPs are specifically popular among young generations. More than two out of three HTP users are dual users. Prospective studies consistently show that in real life HTPs are not effective smoking cessation tools.