Associations between dual use of e-cigarettes and smoking cessation: A prospective study of smokers in England

It has been claimed that use of e-cigarettes in combination with cigarettes outside of a quit attempt ('dual use') reduces quitting among smokers. This study aimed to assess whether dual e-cigarette users have lower smoking cessation rates than (i) exclusive cigarette smokers or (ii) dual users of nicotine replacement therapy (NRT) and cigarettes.

Prospective cohort study of 1,498 smokers in England. The independent variable was dual use of e-cigarettes (n = 292), dual use of NRT (n = 117), or exclusive smoking (n = 1089), assessed at baseline. Outcomes were overall quit rate, past-year quit attempts, and success of quit attempts at 12-month follow-up. Baseline sociodemographic and smoking-related covariates were included.

Overall quit rates were not lower in dual e-cigarette users than exclusive smokers (OR = 1.31, 0.90-1.89). Dual users of e-cigarettes were more likely than exclusive smokers to make a quit attempt, but this difference was not significant after adjustment for covariates (OR = 1.27, 95%CI 0.95-1.69). Among those attempting to quit, success rates did not differ significantly. Dual users of e-cigarettes were less likely to make a quit attempt than dual users of NRT (OR = 0.61, 95%CI 0.38-0.98) but the success rate of quit attempts and overall quit rates did not differ significantly.

In England, dual use of e-cigarettes is not associated with reduced overall quit rates compared with exclusive smoking or dual use of NRT. However, dual use of e-cigarettes is associated with a slightly higher quit attempt rate than exclusive smoking but lower than dual use of NRT.