On 2017 Mar 28, Peter Hajek commented:

After stop-smoking treatment, smokers who quit successfully have no need to use e-cigarettes and so treatment successes are concentrated in the group that did not vape post-treatment. Quit rates are of course higher in this group.

A more informative analysis would compare quit rates at one year in people who failed to stop smoking after treatment and who did and did not try vaping during the follow-up period (though even this would face the problem of self-selection).

The results as reported just show that people who fail to stop smoking with other methods are more likely to try e-cigarettes than those who quit smoking successfully.

It is unfortunate that the Conclusions fail to point this out and instead indicate that vaping undermined quitting. It did no such thing, but as with previous such reports, this is how anti-vaping activists are likely to misrepresent this study.

On 2017 Mar 28, Peter Hajek commented:

After stop-smoking treatment, smokers who quit successfully have no need to use e-cigarettes and so treatment successes are concentrated in the group that did not vape post-treatment. Quit rates are of course higher in this group.

A more informative analysis would compare quit rates at one year in people who failed to stop smoking after treatment and who did and did not try vaping during the follow-up period (though even this would face the problem of self-selection).

The results as reported just show that people who fail to stop smoking with other methods are more likely to try e-cigarettes than those who quit smoking successfully.

It is unfortunate that the Conclusions fail to point this out and instead indicate that vaping undermined quitting. It did no such thing, but as with previous such reports, this is how anti-vaping activists are likely to misrepresent this study.