An increase in the use of e-cigarettes (vaping) has been associated with a drop in smoking by teenagers and young adults, a time trend analysis from the United States has found.

The investigators carried out a literature search using PubMed for surveys on smoking and vaping up to and including 2017. Data on cigarette use by 15-25 year olds were obtained from five different publicly available surveys. 

The first of the surveys began to collect data on vaping in 2011 with all surveys collecting such data by 2014. Information on youth and young adult vaping before 2014 was limited and diverges for the different surveys, but indicates that vaping occurred at relatively low levels from 2011 to 2013, but reached much higher levels by 2014. This year was identified as the tipping point when vaping became popular among young people.

The investigators examined trends within the surveys for both past 30-day use and established smoking among young people. One of the studies indicated that the downward trend in smoking in the past 30 days was more than three times greater in the vaping period, from 2014, (a total annual relative reduction in smoking prevalence of 14.1%) than the long-term trend (an annual relative reduction of 4.6%). With established smoking, trend line analysis of daily cigarette use by 15 to 17 year olds showed about three times the annual relative reduction in the vaping period compared with the long-term trend.  This reduction was even more evident in the 18-21 year age group. Nearly twice the relative reduction in daily smoking was noted in the 22-24 year age group during the vaping period.

The researchers conclude that long-term decline in smoking prevalence among young people in the US accelerated after 2013 when vaping became more widespread. They also found that there was a decline in established smoking, as measured by daily smoking, smoking half a pack a day or having smoked at least 100 cigarettes to date and currently smoking some days or every day, which markedly accelerated when vaping increased.

The authors comment: ‘It is possible that trying e-cigarettes is causally related to smoking for some youth, but the aggregate effect of this relationship at the population level may be small enough that its effects are swamped by other factors that influence smoking behaviour.’

In 2018, a report commissioned by Public Health England Evidence review of e-cigarettes and heated tobacco products concluded that: ‘the evidence does not support the concern that e-cigarettes are a route into smoking among young people.’1 This was at variance with the US National Academies of Sciences, Engineering and Medicine which published a report that concluded there was substantial evidence that vaping among young people is strongly associated with progression to smoking.²

This paper, based on data gathered from young people in the USA, helps shed further light on this dissonance.

Dr Peter Saul