Continuing use of e‐cigarettes after stopping smoking and relapse: Secondary analysis of a large randomised controlled trial

Background and aims Smokers quitting successfully with the help of e‐cigarettes often continue vaping. It is not known whether this promotes or prevents relapse back to smoking. This study aimed to determine whether use of e‐cigarettes after successful smoking cessation affects the probability of relapse later on. Design Secondary analysis of a randomised controlled trial where participants received combination nicotine replacement therapy (NRT) or e‐cigarettes to compare relapse rates in the two study arms and in abstainers who did and did not use e‐cigarettes. Setting Four stop‐smoking services in the United Kingdom. Participants 886 smokers (median age 41, smoking on average 15 cigarettes per day, 48% female) seeking help with stopping smoking. Measurements Main outcome was relapse to smoking by 12 months in participants who were abstinent at 4 weeks or at 6 months. Relapse was defined as abstinence at 4 weeks but not at one year or abstinence at 6 months but not at one year. Abstinence from smoking was defined as no smoking over the past 7 days. E‐cigarette use was defined as using e‐cigarettes at the time of abstinence on at least one day per week. Findings Abstainers in the e‐cigarette arm were less likely to relapse than abstainers in the NRT arm [relative risk (RR) = 0.78, 95% confidence interval (CI) = 0.64–0.96 for relapse between 4 weeks and 1 year; RR = 0.71, 95% CI = 0.55–0.93 for relapse between 6 months and 1 year). Relapse rates over both time periods were also lower in abstainers who used e‐cigarettes compared with abstainers who did not use e‐cigarettes (RR = 0.79, 95% CI = 0.65–0.97 and RR = 0.75, 95% CI = 0.57–0.98, respectively). Conclusions Use of e‐cigarettes after stopping smoking is associated with a reduced risk of relapse.