BACKGROUND: This review examines the effects of using e-cigarettes to help people who smoke achieve smoking (combustible tobacco) abstinence at six months or longer. This review update is part of a living systematic review.
METHODS: Searches for new intervention studies are undertaken monthly, and the review updated whenever findings could affect conclusions. Searches are currently to January 2025. We follow standard Cochrane methods and calculate pooled risk ratios (RRs) with 95% confidence intervals (CI).
RESULTS: This newest update includes 10 new studies, bringing the total number to 100. This update was triggered because previously there was very little evidence comparing nicotine e-cigarettes with varenicline, and since the last update a large trial was published. Compared with varenicline, people randomized to nicotine e-cigarettes had slightly lower quit rates at six months, but CIs included the possibility of no difference and there was evidence of substantial statistical heterogeneity (RR 0.82, 95% CI 0.63 to 1.05, I²=78%, 2 trials, n=359). Findings of increased quit rates with nicotine e-cigarettes compared to nicotine replacement therapy (NRT), to non-nicotine e-cigarettes and to control remain largely unchanged. Additionally in this update, the first trial of its kind compared e-cigarettes to oral nicotine pouches and three studies focused on special populations (people experiencing homelessness, opioid use disorder, and chronic illnesses). We will briefly summarize key findings from the review-to-date, but will focus on the newer findings.
CONCLUSIONS: There is high-certainty evidence that nicotine e-cigarettes increase quit rates compared to NRT. There is less certain evidence that nicotine e-cigarettes may be less or as effective as varenicline. We did not detect evidence of serious harm but larger studies with longer follow-up are needed to fully evaluate safety. Included studies tested regulated nicotine-containing e-cigarettes; illicit products and/or products containing other active substances (e.g. tetrahydrocannabinol (THC)) may have different harm profiles.