Detailed changing use patterns of e-cigs and cigs shows harm enhancement for adults and youth

Until the advent of e-cigarettes nearly 20 years ago tobacco use patterns were pretty stable.  Almost everyone who smoked tobacco smoked cigarettes with a few people smoking cigars.  And some people used smokeless tobacco.  With the advent of e-cigarettes and other new tobacco products, this situation has become much more complicated, particularly since some in the public health community, including the FDA, have promoted e-cigarettes as a strategy for tobacco harm reduction and an “off ramp” for cigarette smoking.  This situation makes understanding the dynamics of transitions between not using tobacco, using cigarettes, e-cigarettes or both (dual use), and stopping tobacco use particularly important.

Epidemiological studies have shown that e-cigarettes are attracting large numbers of youth at low risk of initiating nicotine use with cigarettes and that after initiating nicotine use with e-cigarettes increases the odds that youth will smoke cigarettes. 

Other epidemiological studies show that e-cigarettes as consumer products do not help adults stop smoking cigarettes (i.e., “switch completely”).

The introduction of Juul and other protonated nicotine products that more efficiently deliver nicotine and so have higher addictive potential than earlier generation e-cigarettes further complicates this picture.  On one hand, in making its decisions to authorize the sale of some e-cigarettes, FDA has considered high abuse potential of protonated nicotine e-cigarettes a plus on the assumption that more nicotine delivery makes e-cigarettes a more appealing substitute for cigarettes for adults.  It is also possible, however, that more addictive e-cigarettes would keep people smoking.

Now Andrew Brouwer and colleagues have published “Changing patterns of cigarette and ENDS transitions in the USA: a multistate transition analysis of youth and adults in the PATH Study in 2015-2017 vs 2017-2019” that quantifies transitions between these different conditions in youth and adults before (2015-2017) and after (2017-2019) the Juul era.  

They used the FDA/NIH Population Assessment of Tobacco and Health (PATH) study, which follows thousands of adults and youth forward in time for years to see how cigarette and e-cigarette use shifted between different use patterns:

  • Not using anything
  • Smoking cigarettes only
  • Using e-cigarettes only
  • Dual use (smoking cigarettes and using e-cigarettes concurrently)

Because there are many possible pathways between using and not using these products, the results are complicated, but there are several clear bottom lines:

  • For youth, e-cigarette initiation more than doubled, from 1.6% in 2015-2017 to 3.8% in 2017-2019
  • Among adults there was not an increase in switching from cigarettes or dual use to e-cigarettes only
  • These results were similar in the pre- and post-Juul eras
  • The use of e-cigarettes and dual use became more persistent for both youth and adults
  • The probability of becoming tobacco-free dropped by about half for both adults and youth between 2015-2017 and 2017-2019, regardless of product use pattern

In the FDA’s language, e-cigarettes are not “an off ramp from cigarettes” because adult smokers who use e-cigarettes are not “switching completely.” 

The findings about increased dual use are particularly concerning because dual use is more dangerous than smoking cigarettes or using e-cigarettes alone.

Increasing addictiveness of the new e-cigarettes has been followed by more and more persistent youth use and did not reduce cigarette use for adults, yielding a net increase in harm.

This summary is just scratching the surface of the wealth of detailed information in this paper.  The figure below, shows the results summarized above.  There is lots more in the paper.

Figure 1.  One-year transition probabilities for youth (A, B) and adults (C, D) in 2015–2017 and in 2017–2019  (B,D).

The paper assesses transitions to and from all electronic nicotine delivery devices (ENDS), but during the years they studied almost all ENDS available in the United States were e-cigarettes.

Here is the abstract:

Introduction: It is unknown how recent changes in the tobacco product marketplace have impacted transitions in cigarette and electronic nicotine delivery system (ENDS) use.

Methods: A multistate transition model was applied to 24 242 adults and 12 067 youth in waves 2-4 (2015-2017) and 28 061 adults and 12 538 youth in waves 4 and 5 (2017-2019) of the Population Assessment of Tobacco and Health Study. Transition rates for initiation, cessation and product transitions were estimated in multivariable models, accounting for gender, age group, race/ethnicity and daily versus non-daily product use.

Results: Changes in ENDS initiation/relapse rates depended on age, including among adults. Among youth who had never established tobacco use, the 1-year probability of ENDS initiation increased after 2017 from 1.6% (95% CI 1.4% to 1.8%) to 3.8% (95% CI 3.4% to 4.2%). Persistence of ENDS-only use (ie, 1-year probability of continuing to use ENDS only) increased for youth from 40.7% (95% CI 34.4% to 46.9%) to 65.7% (95% CI 60.5% to 71.1%) and for adults from 57.8% (95% CI 54.4% to 61.3%) to 78.2% (95% CI 76.0% to 80.4%). Persistence of dual use similarly increased for youth from 48.3% (95% CI 37.4% to 59.2%) to 60.9% (95% CI 43.0% to 78.8%) and for adults from 40.1% (95% CI 37.0% to 43.2%) to 63.8% (95% CI 59.6% to 67.6%). Youth and young adults who used both products became more likely to transition to ENDS-only use, but middle-aged and older adults did not.

Conclusions: ENDS-only and dual use became more persistent. Middle-aged and older adults who used both products became less likely to transition to cigarette-only use but not more likely to discontinue cigarettes. Youth and young adults became more likely to transition to ENDS-only use.

The full citation is: Brouwer AF, Jeon J, Jimenez-Mendoza E, Land SR, Holford TR, Friedman AS, Tam J, Mistry R, Levy DT, Meza R. Changing patterns of cigarette and ENDS transitions in the USA: a multistate transition analysis of youth and adults in the PATH Study in 2015-2017 vs 2017-2019. Tob Control. 2023 Mar 28:tc-2022-057905. doi: 10.1136/tc-2022-057905. Epub ahead of print. PMID: 36977570.  It is available here.

Published by Stanton Glantz

Stanton Glantz is a retired Professor of Medicine who served on the University of California San Francisco faculty for 45 years. He conducts research on tobacco and cannabis control and cardiovascular disease/

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