Concurrent E-cigarette Use While Enrolled in a Smoking Cessation Program: Associations between Frequency of use, Motives for Use and Smoking Cessation.

Prior observational studies investigating e-cigarettes use for smoking cessation have found that occasional users have poorer outcomes than either frequent or non-users. Consistent with these studies, occasional users in our data also had poorer outcomes. However, after adjustment for variables associated with cessation success we found that cessation probabilities did not differ between occasional and non-users. These findings are consistent with trial data showing a benefit of e-cigarette use among people trying to quit smoking. Results of this study suggest that differences between trials and previous observational studies may be due to unaddressed confounding in the latter.