[Dual use of e-cigarettes and cigarettes among adolescents before and after the rise of disposable e-cigarettes:...

Use of e-cigarettes and tobacco cigarettes often occurs concurrently. Such dual use is a health concern and may be an indicator of high nicotine dependence. The study examines whether the rise of disposable e-cigarettes in Germany from mid-2021 onwards has reinforced the trend toward dual use.

An interrupted time series design was used. The interruption is the rise of disposable e-cigarettes in 2021. The primary outcome was dual use, defined as the use of both e-cigarettes and combustible cigarettes within the past month. The data are based on 9 waves of the prevention radar, a questionnaire study in grades 5-10. The sample was divided into adolescents in early (9-14 years) and late adolescence (15-17 years). Prevalence estimates were based on segmented regression models within an interrupted time series (ITS) analysis framework. Weighting factors were used to adjust the data to the distribution of the population of students in terms of age, gender and type of school.

A total of 138,458 observations form the data basis. Currently (data collected in 2024/2025), 2.6% of 9-14-year-olds and 9.6% of 15-17-year-olds use both tobacco and e-cigarettes. Before the rise of disposable e-cigarettes, dual use fluctuated numerically slightly and was statistically insignificant in both age groups studied. The rise of disposable e-cigarettes was accompanied by a statistically significant increase in dual use in both age groups. In late adolescence, the proportion increased by 5.9 percentage points (+160%) compared to the average for the years prior to 2021, reaching 2024/2025, and by 1.3 percentage points (+100%) in early adolescence.

According to conservative estimates, the proportion of young people in Germany who consumed both e-cigarettes and cigarettes doubled after the rise of disposable e-cigarettes. In the interests of preventive health protection, some countries such as Belgium, France and the UK have already implemented bans on disposable e-cigarettes. This is also a central demand of various German medical societies under the leadership of the DGP. These study results underpin this demand on health policy.