October 20, 2014

Stanton A. Glantz, PhD

Intensive e-cig users more likely to quit cigs, intermittent users less likely to expect to quit in next year

Lois Biener and J Lee Hargraves just published a nicely done longitudinal study that followed smokers in two cites for around two years and found that, controlling for level of nicotine addiction and demographics, intensive e-cigarette users (defined as using e-cigarettes daily for at least a month) were 6 times more likely to have quit smoking (defined as not smoking for at least 30 days) than smokers who did not use e-cigarettes.
 
They also found that intermittent e-cigarette users (defined as people had used e-cigarettes more than once or twice, but not daily for a month) were no more or less likely to have stopped smoking than non-users, but were were 6 times more likely to expect that they would still be smoking one year into the future.
 
There was not much difference in the motivations for using e-cigarettes (Table 3 of their paper), athough there was a suggestion (p=0.08) that the intensive useres were using them because of health concerns compared to the other groups.  This may explain why the intensive useres were more successful at quitting smoking.  It may be that the intensive users were replacing cigarettes while the non-intensive users were not.  
 
The full paper, "A Longitudinal Study of Electronic Cigarette Use in a Population-based Sample of Adult Smokers: Association with Smoking Cessation and Motivation to Quit," published in Nicotine and Tobacco Research, is available at http://ntr.oxfordjournals.org/content/early/2014/10/07/ntr.ntu200.abstract.html
 

Comments

Comment: 

At follow up, 2-3 years later:
  intensive e-cig users: 80% were still smoking
  intermittent e-cig users: 92% still smoking
  non e-cig users: 88% still smoking
So "six times more likely" overstates the results here, like so many relative comparisons. The actual results are 8% improvement. And that's at best: it seems you have to use the device enough or the results go down from there, even go negative. An accurate summary would therefore be: at best 8%.
And the sad fact is the vast majority across all groups were still smoking. That 8% improvement is a drop in the bucket of 80% fail.
It is a nicely done study. And what it finds is that even when the devices help, they don't help much. The results are underwhelming.
Jon Krueger
 

Comment: 

Dear Jon Krueger:
Would you please document a link to the study that your hypothesis and numbers are derived from?  

Comment: 

... which is linked in the post.

Comment: 

...as all study's EC users had a history of resistance-to-treatment (as all were smokers at baseline).
In response to this problem, Prof. Glantz previously wrote that high-quality adjustments for addiction may account for resistance-to-treatment in such study's, see his comment:
http://tobacco.ucsf.edu/best-study-e-cigs-cessation-so-far-shows-they-do... title="http://tobacco.ucsf.edu/best-study-e-cigs-cessation-so-far-shows-they-do......
Do the adjustments in this study fit that criterion?

Comment: 

No study is perfect, but what they did here was reasonable.

Comment: 

Raw numbers are useful here:
695 survey respondents
364 nonusers/trial users, of which 45 quit
220 intermittent e-cig users, of which 19 quit
111 intensive e-cig users, of which 23 quit
The intensive group got 23 quits; the model suggests it would have been much less otherwise, say 5. So the device enabled 18 people to quit.
In the intermittent group, fewer quit, just 19 people. Similar estimates: say 27 would have otherwise. So the device kept 8 people smoking who would have quit.
That gives a net effect of just 10 additional quits across 331 users, attributed to the device.
The far stronger result is the uniformly poor results. 319 out of 364 nonusers did not quit. 289 out of 331 users did not quit. The vast majority of all users across all groups were still smoking.
Jonathan Krueger
 

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