Looking Back and Going Forward: Roles of Varenicline and Electronic Cigarettes in Smoking Cessation.

Tobacco use is the single largest preventable cause of death in the United States (US). The national goal of reducing the prevalence of adult cigarette smoking to 12% was retained for 20 years due to non-attainment. Meanwhile, varenicline and electronic cigarettes (ECs) became available in the US in 2006 and 2007, respectively, and have been used by many smokers wanting to quit. The purpose of this review is to compare varenicline and ECs in terms of efficacy for smoking cessation after over a decade of widespread use in the US. Data collection for systematic review and qualitative synthesis by a PubMed search using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelinesand the Oxford Quality Scale, respectively, was performed in June 2018 and updated in June 2020. Articles were eligible if published in English as original research in the form of a randomized clinical trial (RCT), a systematic review and meta-analysis, a systematic review, or a cross-sectional study. Eighteen studies were included: nine RCTs, four cross-sectional studies, two meta-analyses, one systematic review, one systematic review and meta-analysis, and one cohort study. No head-to-head RCT compared varenicline to ECs. In four RCTs, varenicline was more effective than placebo for smoking cessation. In two RCTs, ECs were more effective than placebo but a meta-analysis of 20 studies reported a statistically significant decrease in the odds of quitting smoking using ECs as compared to placebo. To conclude, varenicline and ECs have data suggesting efficacy for smoking cessation; however, unlike varenicline, ECs were not effective in all studies.