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• On the importance of using quit-attempters and focusing on why e-cigarettes were used to assessing e-cigarettes role in smoking cessation
  John P Pierce, Tarik Benmarhnia, Sara McMenamin, Martha White, Dennis R Trinidad and David R Strong
  Published on: 17 December 2018

• Published on: 17 December 2018

  On the importance of using quit-attempters and focusing on why e-cigarettes were used to assessing e-cigarettes role in smoking cessation

  • John P Pierce, professor Moores Cancer Center, University of California, San Diego
  • Other Contributors:
    • Tarik Benmarhnia, Assistant Professor
    • Sara McMenamin, Assistant Professor
    • Martha White, Senior programmer
    • Dennis R Trinidad, Associate Professor
    • David R Strong, Professor

  NOT PEER REVIEWED

  Berry et al (1) report an analysis of two waves of the Population Assessment of Tobacco and Health (PATH) study focused on the association between the initiation of e-cigarette use by Wave 2 and cigarette abstinence/reduction assessed at Wave 2. They conclude that daily e-cigarette use is associated with both cigarette abstinence and reduced consumption among continuing smokers. While this addresses an important question, we argue that such analyses should be adjusted for the reason e-cigarettes are being used.

  From Wave 1 of PATH (2), we know that ~75% of smokers agreed that e-cigarettes were useful to help people quit. However, ~80% agreed that e-cigarettes allowed someone to replace a cigarette where smoking was prohibited. From the first reason, we can hypothesize that e-cigarette use might be associated with cigarette abstinence/reduction. However, from the second reason, we can also hypothesize that e-cigarettes would be associated with neither cigarette abstinence nor reduction. The recent National Academies report (3) recommended that any assessment of the role of e-cigarettes in cigarette cessation/reduction should focus on smokers who used e-cigarettes to help them quit.
  PATH Wave 2 data does include information on whether smokers tried to quit in the previous year, as well as whether they used e-cigarettes to aid the last quit attempt. Previous research (4) has shown that over half of the smoking population will not ha...

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  NOT PEER REVIEWED

  Berry et al (1) report an analysis of two waves of the Population Assessment of Tobacco and Health (PATH) study focused on the association between the initiation of e-cigarette use by Wave 2 and cigarette abstinence/reduction assessed at Wave 2. They conclude that daily e-cigarette use is associated with both cigarette abstinence and reduced consumption among continuing smokers. While this addresses an important question, we argue that such analyses should be adjusted for the reason e-cigarettes are being used.

  From Wave 1 of PATH (2), we know that ~75% of smokers agreed that e-cigarettes were useful to help people quit. However, ~80% agreed that e-cigarettes allowed someone to replace a cigarette where smoking was prohibited. From the first reason, we can hypothesize that e-cigarette use might be associated with cigarette abstinence/reduction. However, from the second reason, we can also hypothesize that e-cigarettes would be associated with neither cigarette abstinence nor reduction. The recent National Academies report (3) recommended that any assessment of the role of e-cigarettes in cigarette cessation/reduction should focus on smokers who used e-cigarettes to help them quit.
  PATH Wave 2 data does include information on whether smokers tried to quit in the previous year, as well as whether they used e-cigarettes to aid the last quit attempt. Previous research (4) has shown that over half of the smoking population will not have tried to quit in the previous year. By including these non-attempters, who by definition cannot have quit, Berry et al (1) may have introduced an important bias toward finding a higher daily e-cigarette effect on abstinence. We expect that daily e-cigarette use at Wave 2 will be much higher among those who made a recent quit attempt than in those who did not.

  In their supplement tables (TableS3), they include an analysis of those who made a quit attempt prior to Wave 1(rather than between Waves 1 and 2). Using this analysis, there is a drastic reduction in the effect size amplitude and in the absolute number of involved smokers. We would expect similar, or even larger, reduction in effect estimates were they to have restricted their analysis to those who made a quit attempt in the year prior to Wave 2 and included reason for using e-cigarettes.

  In order to know the effect of e-cigarettes on cessation, those who used an e-cigarette to help them to quit should be contrasted with comparable non-users: those who used other aids to quit as well as to those who quit unaided. There are numerous important potential confounders for these comparisons as it is well known that those who are least likely to be successful in the quit attempt are the most likely to use an aid. (5) For unbiased analyses, the exposure of interest needs to be isolated and covariate balance achieved between exposed and unexposed. There is a role for methodological approaches that help achieve covariate balance, such as propensity score matching, in deciding whether e –cigarettes improve population smoking cessation.

  References:
  1. Berry KM, Reynolds LM, Collins JM, Siegel MB, Fetterman JL, Hamburg NM, Bhatnagar A, Benjamin EJ, Stokes A. E-cigarette initiation and associated changes in smoking cessation and reduction: the Population Assessment of Tobacco and Health Study, 2013-2015.Tob Control. 2018 Mar 24. pii: tobaccocontrol-2017-054108. doi: 10.1136/tobaccocontrol-2017-054108.
  2. Coleman BN, Rostron B, Johnson SE, Ambrose BK, Pearson J, Stanton CA, et al. Electronic cigarette use among US adults in the Population Assessment of Tobacco and Health (PATH) Study, 2013–2014. Tobacco Control. 2017. doi: 10.1136/tobaccocontrol-2016-053462.
  3. National Academies of Sciences Engineering, and Medicine,. Public Health Consequences of E-Cigarettes. Washington, DC: Health and Medicine Division, National Academies of Sciences, Engineering, and Medicine, 2018
  4. Zhu S-H, Lee M, Zhuang Y, Gamst A, Wolfson T. Interventions to increase smoking cessation at the population level: How much progress has been made in the last two decades? Tob Control. 2012;212:110–118
  5. Leas EC, Pierce JP, Benmarhnia T, White MM, Noble ML, Trinidad DR, Strong DR. Effectiveness of Pharmaceutical Smoking Cessation Aids in a Nationally Representative Cohort of American Smokers. J Natl Cancer Inst. 2017 Dec 21. doi: 10.1093/jnci/djx240

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  Conflict of Interest:
  None declared.

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