The United Kingdom embraces vaping as a promising smoking cessation tool. As a result, encouraging the use of vapor products to achieve or maintain abstinence from combustible cigarettes has yielded a sizable decrease in the U.K.’s smoking rate. However, it is necessary to evaluate any public health intervention on more than one outcome. To be an effective cessation device, vapor products must not only help smokers quit, but they also must not increase relapse to combustible products. Accordingly, to test the relationship between vaping and eventual relapse to smoking, a recent study  by Leonie S. Brose et al. surveyed adult smokers, ex-smokers and vapers in the United Kingdom to describe the associations between use of vapor products and relapse to smoking, and to glean insight into the characteristics of those vapers who do relapse.
In so doing, the authors utilized a sample of smokers, recent ex-smokers and vapers who completed a multi-year survey in 2016. From the first survey, they selected participants who reported sustained abstinence from combustible cigarettes for at least two months. Participants who completed the follow-up survey a year later, in 2017, were included in the analysis. Brose et al. then evaluated the association between vapor product use at baseline and smoking relapse at follow-up.
By assessing the exposure—vaping—and the outcome—smoking relapse—at different points in time, the authors ensured that the exposure preceded the outcome thereby correcting a common limitation of studies that measure both variables at the same point in time. Their study also limited potential bias by excluding smokers who were abstinent for less than two months. This is because previous research cited by the authors suggests that smokers are most likely to relapse during the first month after quitting. This is consistent for all quit methods, including nicotine replacement therapy (NRT), and thus using two-month abstinence as a strict definition decreased the likelihood that failed quit attempts might artificially inflate the prevalence of relapse.
Ultimately, Brose et al. found that participants who vaped daily, non-daily or in the past were no more likely to relapse than participants who had never used vapor products, controlling for gender, age, NRT use, income and time since quitting. In fact, relapse rates did not differ on any characteristic other than age and time since quitting smoking. Unsurprisingly, time since quitting smoking was strongly associated with relapse. Participants who had quit more than two, but less than twelve months prior to the first survey had nearly four times the odds of relapse compared to participants who had quit smoking at least twelve months prior. This suggests that time since quitting—rather than method of alternative nicotine delivery—is the most significant determining factor in whether or not a person will return to smoking.
For those who did use vapor products, the authors were interested in determining whether the characteristics of the products they used to quit predicted relapse. Accordingly, they assessed the association between relapse and certain characteristics of vaping products, such as device type and nicotine strength. This portion of the analysis only included participants who reported daily or frequent, non-daily use of vapor products at baseline. Among this smaller group—all of whom used vapor products with some regularity—non-daily vapers had almost four times the odds of relapse compared to participants who vaped daily. The results of this analysis also showed some differences in odds of relapse based on device type: Non-modular systems, such as vape pens, disposable products and pod systems, were more strongly associated with relapse than modular systems, which generally offer a more customizable use experience. Nicotine strength and NRT use were not predictive of relapse in this analysis. Once again in this group, mirroring the analysis of relapse based on any use of vapor products, time since quitting smoking was most strongly associated with the odds of relapse among the sample that included daily and non-daily vapers. In light of this, for areas considering placing limits on nicotine strength, this study does not support the theory that vapor products containing higher nicotine concentrations are associated with smoking relapse.
These findings provide evidence that use of vapor products is not predictive of relapse when compared to smokers who do not use vapor products. It also suggests that those who vaped more regularly after smoking actually had higher odds of sustained smoking cessation. When considering the value of vapor products for that specific purpose, these results help alleviate the concern that former smokers who vape are more likely to return to smoking than those who do not. And moreover, based on Brose et al.’s findings, to overlook—or arbitrarily discourage—daily vapor product use as a strategy to help newly abstinent smokers avoid returning to combustible cigarettes is unwise.
As policymakers consider the public health value of vapor products, they should keep the results of this study in mind. Currently, FDA-approved smoking cessation products have low rates  of successful abstinence after one year. This study suggests that vaping may be a more successful alternative, which may benefit both the health of individual smokers and public health efforts more broadly.
Although the study has several limitations—its sample size is small, and the authors note that statistical analyses of the strength of association suggest that the dataset was insensitive to differences between groups for some variables—the findings nevertheless add to the evidence that vapor product use among former smokers does not promote relapse and may, in fact, be more successful than other currently approved NRT.
- “study”: https://www.ncbi.nlm.nih.gov/pubmed/31888637
- “low rates”: https://www.rstreet.org/2019/08/07/tobacco-harm-reduction-evidence-update/