Efficacy of Electronic Cigarettes for Smoking Cessation: A Systematic Review and Meta-Analysis

Objective: to synthesize evidence about the efficacy of electronic cigarettes versus Nicotine Replacement Therapy and placebo to quit smoking.

Data sources: We searched for clinical trials with no publication date restriction until December 2019. The search included CENTRAL, MEDLINE, PsycINFO, Science Direct, Center for reviews and dissemination and HTA database and Trip database, clinical trials registries, gray literature and examined the references of relevant articles.

Inclusion and exclusion criteria: Two review authors independently checked the titles and abstracts then the full text of initial hits. Main outcomes were sustained continuous abstinence rate, 7-day point prevalence abstinence rate, sustained reduction of 50% or greater in baseline cigarette consumption and adverse effects.

Data extraction and synthesis: Two review authors independently extracted data and assessed risk of bias using the Cochrane RoB 2 tool. We conducted a random-effects model through the Mantel-Haenszel method.

Results: We retrieved 12 trials involving 9863 participants. CO- validated 1-month continuous abstinence rate improved by 33% in the e-cigarettes group (range 6-66%, moderate evidence). We are uncertain if e-cigarettess influence continuous abstinence rate at 3-, 6- and 12 months as well as sustained reduction of 50% or greater in baseline cigarette consumption at different follow-up periods. One study of 884 participants displayed improved 12-month 7-day point abstinence by 46% (range 17%-82%). E-cigarettes may increase or do not affect the proportion of serious adverse effect at 6 and 12 months follow up.

Conclusion: Very low certainty evidence supported e-cigarettess to help quit smoking in the short term. There is not enough evidence to determine if e-cigarettess are a safe and efficacious means of smoking cessation in the long term (12+ months).