18th study shows that smokers who use e-cigs are significantly less likely to quit smoking

Nancy Rigotti and colleagues just published a well-done study of the effects of e-cigarette use on smoking cessation among a cohort of smokers who planned to stop smoking after being hospitalized.  They randomized smokers into two groups, one that was given an active intervention to help them quit smoking and a control group who just received advice to quit.  Smokers were followed prospectively for 6 months  to examine successful quitting as a function of whether or not the patients used e-cigarettes as well as the assigned therapy.

Only 10.1% of the smokers who used e-cigarettes had quit smoking after 6 months compared to 26.6% of smokers who did not use e-cigarettes.  In other words, smokers who used e-cigarettes while trying to quit had their chances of successfully quitting cut by two thirds.

This is a very strong study because it is done prospectively by a well-respected group.  In addition, Rigotti and her colleagues carefully controlled for differences between the e-cigarette users and non-e-cigarette users and made a strong case that their results were very unlikely to be due to some unobserved confounder.

The paper brings to 18 the number of studies that have found that smokers who use e-cigarettes are significantly less likely to quit smoking compared to 6 that show significant benefits for quitting.  (There are 9 others that did not reach statistical significance, 5 than tended to show less quitting and 4 that tended to show more quitting.)

Given the strength of this study, together with the larger literature, I was surprised that the authors concluded that, “Additional study is needed to determine whether regular use of e-cigarettes aids or hinders smoking cessation.”   How many more studies do we need before the e-cigarette enthusiasts will admit that, for most people, e-cigarettes, as actually used, make it harder (not easier) to quit smoking?

Here is the abstract:

Background:  Many smokers report using e-cigarettes to help them quit smoking, but whether e-cigarettes aid cessation efforts is uncertain.

Objective:  To determine whether e-cigarette use after hospital discharge is associated with subsequent tobacco abstinence among smokers who plan to quit and are advised to use evidence-based treatment.

Design:  Secondary data analysis of a randomized controlled trial. (ClinicalTrials.gov: NCT01714323 [parent trial]).

Setting: 3 hospitals.

Participants:  1357 hospitalized adult cigarette smokers who planned to stop smoking, received tobacco cessation counseling in the hospital, and were randomly assigned at discharge to a tobacco treatment recommendation (control) or free tobacco treatment (intervention).

Measurements:  Self-reported e-cigarette use (exposure) was assessed 1 and 3 months after discharge; biochemically validated tobacco abstinence (outcome) was assessed 6 months after discharge.

Results:  Twenty-eight percent of participants used an e-cigarette within 3 months after discharge. In an analysis of 237 propensity score-matched pairs, e-cigarette users were less likely than nonusers to abstain from tobacco use at 6 months (10.1% vs. 26.6%; risk difference, -16.5% [95% CI, -23.3% to -9.6%]). The association between e-cigarette use and quitting varied between intervention patients, who were given easy access to conventional treatment (7.7% vs. 29.8%; risk difference, -22.1% [CI, -32.3% to -11.9%]), and control patients, who received only treatment recommendations (12.0% vs. 24.1%; risk difference, -12.0% [CI, -21.2% to 2.9%]) (P for interaction = 0.143).

Limitations:  Patients self-selected e-cigarette use. Unmeasured confounding is possible in an observational study.

Conclusion:  During 3 months after hospital discharge, more than a quarter of smokers attempting to quit used e-cigarettes, mostly to aid cessation, but few used them regularly. This pattern of use was associated with less tobacco abstinence at 6 months than among smokers who did not use e-cigarettes. Additional study is needed to determine whether regular use of e-cigarettes aids or hinders smoking cessation.

The full citation is:   Rigotti NA, Chang Y, Tindle HA, Kalkhoran SM, Levy DE, Regan S, Kelley JHK, Davis EM, Singer DE.  Association of E-Cigarette Use With Smoking Cessation Among Smokers Who Plan to Quit After a Hospitalization: A Prospective Study.  Ann Intern Med. 2018 Mar 27. doi: 10.7326/M17-2048. [Epub ahead of print].  It is available here.